Brijesh Tripathi - Academia.edu (original) (raw)

Papers by Brijesh Tripathi

Research paper thumbnail of Thermal Stability of Supercapacitor for Hybrid Energy Storage System in Lightweight Electric Vehicles: Simulation and Experiments

Journal of Modern Power Systems and Clean Energy

Recent research findings indicate that the non-monotonic consumption of energy from lithium-ion (... more Recent research findings indicate that the non-monotonic consumption of energy from lithium-ion (Li-ion) batteries results in a higher heat generation in electrical energy storage systems. During peak demands, a higher heat generation due to high discharging current increases the temperature from 80°C to 120°C, thereby resulting in thermal runaway. To address peak demands, an additional electrical energy storage component, namely supercapacitor (SC), is being investigated by various research groups. This paper provides insights into the capability of SCs in lightweight electric vehicles (EVs) to address peak demands using the worldwide harmonized light-duty driving test cycle (WLTC) driving profile in MATLAB/Simulinkat different ambient temperatures. Simulation results indicate that temperature imposes a more prominent effect on Li-ion batteries compared with SCs under peak demand conditions. The effect of the discharging rate limit on the Li-ion battery current is studied. The result shows that SCs can accommodate the peak demands for a low discharging current limit on the battery, thereby reducing heat generation. Electrochemical impedance spectroscopy and cyclic voltammetry are performed on SCs to analyze their thermal performance at different temperatures ranging from 0°C to 75°C under different bias values of − 0.6, 0, 0.6, and 1V, respectively. The results indicate a higher specific capacitance of the SC at an optimum operation temperature of 25°C for the studied bias. This study shows that the hybrid combination of the Li-ion battery and SC for a light-weight EV can address peak demands by reducing thermal stress on the Li-ion battery and increasing the driving range.

Research paper thumbnail of Effect of Varying Illumination and Temperature on Steady-State and Dynamic Parameters of Dye-Sensitized Solar Cell Using AC Impedance Modeling

The steady-state current-voltage curve and dynamic response of a dye-sensitized solar cell (DSSC)... more The steady-state current-voltage curve and dynamic response of a dye-sensitized solar cell (DSSC) is mathematically modeled based on electrical equivalent circuit. The effect of temperature and illumination on the steady-state and dynamic parameters of dye-sensitized solar cells is studied. It is found that the dynamic resistance of DSSC decreases from 619.21 Ω to 90.34 Ω with the increase in illumination level from 200 W/m 2 to 800 W/m 2 . A positive temperature coefficient of dynamic resistance is observed. The interfacial charge transfer and recombination losses at the oxide/dye/electrolyte interface are found to be the most influential factor on the overall conversion efficiency and included in the mathematical model. The saturation current of rectifying diode and saturation current of recombination diode are responsible for the transfer recombination losses and have major influence on the overall conversion efficiency.

Research paper thumbnail of Feasibility Study of Commercial Silicon Solar PV Mo Dule Based Low-Concentration Photovoltaic System

A concentrator photovoltaic (CPV) system has a potential fo r further cost reduction of solar Pho... more A concentrator photovoltaic (CPV) system has a potential fo r further cost reduction of solar Photovoltaic (PV) power as compared to flat panel PV. In t his work a piecewise linear parabolic trough is designed to reflect the solar radiation with uniform i ntensity on the PV module receiver system. Silicon solar PV module based CPV system is modeled and sim ulat on is done to study the variation of output power, open-circuit voltage and short-circuit current wi th respect to module temperature and irradiance. These simulation results are experimentally va idated using a CPV (CR ~ 8) system developed in laboratory. The results confirms that the comm erically available silicon solar PV module performs satisfactorily upto ~ 8 Sun concentration.

Research paper thumbnail of Solar Energy From Cells To Grid

Research paper thumbnail of Impact of Potential‐Induced Degradation on Different Architecture‐Based Perovskite Solar Cells

Research paper thumbnail of Investigating the effect of quantized confining energy on the quantum coulomb blockade phenomena in single-electron transistor

Solid State Communications

Research paper thumbnail of Investigating Two-Step MAPbI3 Thin Film Formation during Spin Coating by Simultaneous in Situ Absorption and Photoluminescence Spectroscopy

Journal of Materials Chemistry A

Until today, the two-step processing method represents an attractive route for the thin film form... more Until today, the two-step processing method represents an attractive route for the thin film formation of halide perovskites. However, a fundamental understanding about the film formation dynamics in case of...

Research paper thumbnail of Modeling of four-terminal solar photovoltaic systems for field application

Research paper thumbnail of Graphene oxide-molybdenum oxide composite with improved hole transport in bulk heterojunction solar cells

AIP Advances

Solution processed hole transport layer based on graphene oxide (GO) and molybdenum oxide (MoO 3)... more Solution processed hole transport layer based on graphene oxide (GO) and molybdenum oxide (MoO 3) composite in bulk heterojunction organic solar cell (OSC) devices offer low cost, improved performance compared to conventional organic solar cells. Here, we have made a study comparing the power conversion efficiency (PCE) of this composite to the pristine GO and MoO 3 as a hole transport layer in the organic photovoltaics. The devices with the composite shows optimized performance with PCE of ∼ 5.1%, while the pristine GO and MoO 3 display 1.59% and 2.5%, respectively. These differences are attributed to the lower short circuit current (Jsc) and thereby lower fill factor (FF) with respect to the GO and MoO 3. Nevertheless, the composite based devices exhibits improved optical absorption and photoluminescence quenching as compared to pristine interface layer. This study intends to highlight efficient modulation of the interface barrier of hole transport layer which allow us to give faster transport and extraction of the charge carrier efficiently at the electrodes.

Research paper thumbnail of Potential‐Induced Degradation and Recovery of Perovskite Solar Cells

Solar RRL

This study has received funding from the project PV OpMaat, financed by the cross border collabor... more This study has received funding from the project PV OpMaat, financed by the cross border collaboration program Interreg V Flanders-Netherlands with financial support of the European Funds for Regional Development. B.C. is a postdoctoral fellow of the Research Fund Flanders (FWO).

Research paper thumbnail of Study of transport and recombination mechanism in hole transporter free perovskite solar cell

Materials Research Express

Despite advanced research on device structures and processing conditions of perovskite-based sola... more Despite advanced research on device structures and processing conditions of perovskite-based solar cell, many performance aspects are still less understood. The situation becomes more complex in the case of hole transport free (HTM), open-air synthesized solar cell which has an immense potential for low cost and easy fabrication processes. In this work, a correlation between performance deciding parameters with transport and recombination mechanism for the HTM free open-air synthesized perovskite solar cells are studied. The current-voltage response of the fabricated solar cells is not only limited by the phenomenon of transport and recombination but also the injection efficiency of charge carriers. In comparison with the efficient HTM perovskite solar cells, the domination of space charge limited current inside the perovskite layer in HTM free solar cell limits the performance of the device. The interfacial energetic of the active junction i.e. TiO2/perovskite was studied using capacitive analysis that depicts the charge distribution and kinetics in a solar cell. Indeed, the present work illustrates the way to identify the performance limiting parameters in HTM free perovskite solar cell to improve the performance of future devices.

Research paper thumbnail of Estimating various losses in c-Si solar cells subjected to partial shading: insights into J–V performance reduction

Journal of Computational Electronics

This article reports the effect of partial shading (PS) on the electrical output of a solar cell ... more This article reports the effect of partial shading (PS) on the electrical output of a solar cell using the two-diode model. The reduction in electrical performance parameters induced by various recombination losses has been explained for c-Si solar cells under the effect of PS. The PS mainly affects the short-circuit current density ({J}_{\mathrm{SC}})$$(JSC) and efficiency (\eta )$$(η) of the solar cells. {J}_{\mathrm{SC }}$$JSC and \eta η decrease from 37.84 to 5.48 mA \hbox {cm}^{-2}$$cm-2 and from 18.31 to 2%, respectively. Among all the energy losses encountered for PS, spatial relaxation and recombination losses are the dominating factors responsible for the reduction in {J}_{\mathrm{SC}}$$JSC. PC1D and Griddler simulations have been performed to evaluate the effect of front surface and bulk recombination. The PC1D simulated external quantum efficiency is governed by the front and back surface recombination velocity and carrier life time of the charge carriers under PS. The power loss ($${P}_{\mathrm{e}}$$Pe) of {\sim }$$∼ 34% from the emitter region has been determined by resistance analysis in correlation with the recombination in the emitter region of the solar cells under PS.

Research paper thumbnail of Quantum mechanical investigation of optoelectronic properties of gold nanoparticle attached titanium dioxide nanorods for device applications

Journal of Nanoparticle Research

AbstractThis article reports gold nanoparticle (Au-NP) induced absorption enhancement in hydrothe... more AbstractThis article reports gold nanoparticle (Au-NP) induced absorption enhancement in hydrothermally synthesized titanium dioxide nanorods (TiO2-NRs) with a possibility of the deposition of hybrid nanostructures on the transparent substrates. The localized surface plasmon resonance (LSPR) and hot electron transfer behaviour of Au-NPs attached to the TiO2-NRs has been correlated to their photocatalytic response. The photocurrent enhancement observed in amperometric studies has been explained on the basis of excess electron density in the conduction band of TiO2 due to hot electron transfer from the attached Au-NPs (size in the range of 3 to 44 nm). The quantum mechanical calculation of the electron transmission probability from the resonant Au-NP to the conduction band of TiO2-NR has been presented with respect to the wavelength of the incident spectrum. Further, the role of Au-NP size dependent electron work function has been correlated to the electron transmission probability. This study provides a quantum mechanical explanation to the better response of Au-NPs/TiO2-NRs system for photo-catalytic device applications. Graphical abstractᅟ

Research paper thumbnail of Electro-analytical investigation of potential induced degradation in mc-silicon solar cells: case of sodium ion induced inductive loop

Physical chemistry chemical physics : PCCP, Jan 18, 2018

Potential induced degradation of the shunt type (PID-s) in multi-crystalline silicon (mc-Si) sola... more Potential induced degradation of the shunt type (PID-s) in multi-crystalline silicon (mc-Si) solar cells is becoming critical for performance reduction of solar panels in large scale photovoltaic (PV) power plants. In this article PID-s has been investigated by applying high voltage stress on mc-Si solar cells for their degradation and recovery and results have been explained on the basis of DC and AC characterization. The efficiency decreases drastically from 15.7% to 2.9% due to a high voltage stress of -800 V at 85 °C for 48 hours, which is attributed to a reduction in shunt resistance and an increase in depletion and diffusion capacitances. The reduction in electrical performance due to PID-s has been further explained by morphological, structural and elemental analysis. Observed negative capacitance behaviour in impedance spectra of mc-Si solar cells after PID-s has been attributed to structural deformation caused by potential induced migration of sodium ions (Na+) into mc-Si. ...

Research paper thumbnail of {"__content__"=>"Investigating the influence of charge transport on the performance of PTB7:PCBM based organic solar cells.", "sub"=>{"__content__"=>"71"}}

Physical chemistry chemical physics : PCCP, Jan 14, 2018

A key challenge for researchers in the field of organic solar cells (OSCs) is to develop a physic... more A key challenge for researchers in the field of organic solar cells (OSCs) is to develop a physical model for a device that correctly describes the charge carrier transport phenomenon. In this article, an analytical study on the charge carrier transport phenomenon in an OSC is reported, which expresses a balance between free charge carrier generation and recombination in low mobility PTB7:PC71BM blend layers. First, the current density-voltage (J-V) data for the fabricated OSC were extracted from experiments by varying the incident power light intensity (IPL) and then analysis through theoretical simulation was used to quantify the dominant interface recombination parameters limiting the device's performance. It was found that although the generation of free charge carriers increased at higher IPL values, the performance of the device remained low due to poor electrical transport properties which resulted in a considerable accumulation of generated charge carriers in the active ...

Research paper thumbnail of Investigating the Role of Substrate Tin Diffusion on Hematite Based Photoelectrochemical Water Splitting System

Journal of nanoscience and nanotechnology, 2018

Hematite (α-Fe2O3) nanostructures have been extensively studied as photo-anodes for the conversio... more Hematite (α-Fe2O3) nanostructures have been extensively studied as photo-anodes for the conversion of sunlight into chemical fuels by water splitting. A number of factors limit the photo-activity of pristine hematite nanostructures, including poor electrical conductivity and long penetration depth of light. Previous studies have shown that use of tin (Sn) as an n-type dopant can substantially enhance the photoactivity of hematite photoanodes by modifying their morphological, optical and electrical properties. This article presents impedance spectroscopic investigation of interplay between Sn-doping and the photoanode performance for photoelectrochemical water splitting using hematite nanostructure. Mott-Schottky measurements show that the Sn dopant serves as electron donor and increases the donor density of Sn-doped α-Fe2O3 nanostructured layer to 2.39 × 1019 cm-3. Photoelectrochemical impedance spectroscopy shows efficient photogenerated charge transfer from hematite to electrolyte...

Research paper thumbnail of Theoretical maximum performance evaluation of third generation silicon solar cell consisting of nc-Si:H/a-Si:H quantum wells

Superlattices and Microstructures

Abstract The maximum performance of nc-Si:H/a-Si:H quantum well solar cell is theoretically evalu... more Abstract The maximum performance of nc-Si:H/a-Si:H quantum well solar cell is theoretically evaluated by studying the spectral absorption of incident radiation with respect to the number of inserted nc-Si:H quantum well layers. Fundamental intrinsic properties of a-Si:H and nc-Si:H materials reported in literature have been used to evaluate the performance parameters. Enhanced spectral absorption is recorded due to insertion of nc-Si:H quantum well layers in the intrinsic region of a-Si:H solar cell. By inserting 50 QW layers of nc-Si:H in the intrinsic region of the a-Si:H solar cell, the short-circuit current density (J SC ) increases by ∼100% as compared to the baseline whereas the open-circuit voltage (V OC ) decreases by ∼38%. The decrease in V OC is explained on the basis of quasi-Fermi level separation under the illuminated state of solar cell. Theoretical maximum efficiency, having the combined effect of the increase in J SC and decrease in V OC , has increased by ∼24% in comparison with the baseline due to the use of QW as calculated using ideal carrier lifetime value. With a realistic carrier lifetime of the state-of-the-art a-Si:H solar cells, the addition of QWs do not yield any significant gain. From this study, it is concluded that a high carrier lifetime is required to gain a noteworthy benefit from the nc-Si:H/a-Si:H QWs.

Research paper thumbnail of Photo-induced characteristic study of the smallest fullerene fragment, 1,6,7,10-tetramethylfluoranthene as an acceptor

New J. Chem.

In this study, the use of the novel 1,6,7,10-tetramethylfluoranthene as an acceptor in the organi... more In this study, the use of the novel 1,6,7,10-tetramethylfluoranthene as an acceptor in the organic solar cell has been demonstrated.

Research paper thumbnail of Impedance Spectroscopic Investigation of the Degraded Dye-Sensitized Solar Cell due to Ageing

International Journal of Photoenergy

This paper investigates the effect of ageing on the performance of dye-sensitized solar cells (DS... more This paper investigates the effect of ageing on the performance of dye-sensitized solar cells (DSCs). The electrical characterization of fresh and degraded DSCs is done under AM1.5G spectrum and the current density-voltage (J-V) characteristics are analyzed. Short circuit current density (JSC) decreases significantly whereas a noticeable increase in open circuit voltage is observed. These results have been further investigated electroanalytically using electrochemical impedance spectroscopy (EIS). An increase in net resistance results in a lower JSC for the degraded DSC. This decrease in current is mainly due to degradation of TiO2-dye interface, which is observed from light and dark J-V characteristics and is further confirmed by EIS measurements. A reduction in the chemical capacitance of the degraded DSC is observed, which is responsible for the shifting of Fermi level with respect to conduction band edge that further results in an increase of open circuit voltage for the degrade...

Research paper thumbnail of Revealing the correlation between charge carrier recombination and extraction in an organic solar cell under varying illumination intensity

Physical chemistry chemical physics : PCCP, Jan 20, 2017

The design and fabrication of better excitonic solar cells are the need of the hour for futuristi... more The design and fabrication of better excitonic solar cells are the need of the hour for futuristic energy solutions. This designing needs a better understanding of the charge transport properties of excitonic solar cells. One of the popular methods of understanding the charge transport properties is the analysis of the J-V characteristics of a device through theoretical simulation at varied illumination intensity. Herein, a J-V characteristic of a polymer:fullerene based bulk heterojunction (BHJ) organic solar cells (OSCs) of structure ITO/PEDOT:PSS (∼40 nm)/PTB7:PC71BM (∼100 nm)/Al (∼120 nm) is analyzed using one- and two-diode models at varied illumination intensity in the range of 0.1-2.33 Sun. It was found that the double diode model is better with respect to the single diode model and can explain the J-V characteristics of the OSCs correctly. Further, the recombination mechanism is investigated thoroughly and it was observed that fill factor (FF) is in the range of 62.5%-41.4% ...

Research paper thumbnail of Thermal Stability of Supercapacitor for Hybrid Energy Storage System in Lightweight Electric Vehicles: Simulation and Experiments

Journal of Modern Power Systems and Clean Energy

Recent research findings indicate that the non-monotonic consumption of energy from lithium-ion (... more Recent research findings indicate that the non-monotonic consumption of energy from lithium-ion (Li-ion) batteries results in a higher heat generation in electrical energy storage systems. During peak demands, a higher heat generation due to high discharging current increases the temperature from 80°C to 120°C, thereby resulting in thermal runaway. To address peak demands, an additional electrical energy storage component, namely supercapacitor (SC), is being investigated by various research groups. This paper provides insights into the capability of SCs in lightweight electric vehicles (EVs) to address peak demands using the worldwide harmonized light-duty driving test cycle (WLTC) driving profile in MATLAB/Simulinkat different ambient temperatures. Simulation results indicate that temperature imposes a more prominent effect on Li-ion batteries compared with SCs under peak demand conditions. The effect of the discharging rate limit on the Li-ion battery current is studied. The result shows that SCs can accommodate the peak demands for a low discharging current limit on the battery, thereby reducing heat generation. Electrochemical impedance spectroscopy and cyclic voltammetry are performed on SCs to analyze their thermal performance at different temperatures ranging from 0°C to 75°C under different bias values of − 0.6, 0, 0.6, and 1V, respectively. The results indicate a higher specific capacitance of the SC at an optimum operation temperature of 25°C for the studied bias. This study shows that the hybrid combination of the Li-ion battery and SC for a light-weight EV can address peak demands by reducing thermal stress on the Li-ion battery and increasing the driving range.

Research paper thumbnail of Effect of Varying Illumination and Temperature on Steady-State and Dynamic Parameters of Dye-Sensitized Solar Cell Using AC Impedance Modeling

The steady-state current-voltage curve and dynamic response of a dye-sensitized solar cell (DSSC)... more The steady-state current-voltage curve and dynamic response of a dye-sensitized solar cell (DSSC) is mathematically modeled based on electrical equivalent circuit. The effect of temperature and illumination on the steady-state and dynamic parameters of dye-sensitized solar cells is studied. It is found that the dynamic resistance of DSSC decreases from 619.21 Ω to 90.34 Ω with the increase in illumination level from 200 W/m 2 to 800 W/m 2 . A positive temperature coefficient of dynamic resistance is observed. The interfacial charge transfer and recombination losses at the oxide/dye/electrolyte interface are found to be the most influential factor on the overall conversion efficiency and included in the mathematical model. The saturation current of rectifying diode and saturation current of recombination diode are responsible for the transfer recombination losses and have major influence on the overall conversion efficiency.

Research paper thumbnail of Feasibility Study of Commercial Silicon Solar PV Mo Dule Based Low-Concentration Photovoltaic System

A concentrator photovoltaic (CPV) system has a potential fo r further cost reduction of solar Pho... more A concentrator photovoltaic (CPV) system has a potential fo r further cost reduction of solar Photovoltaic (PV) power as compared to flat panel PV. In t his work a piecewise linear parabolic trough is designed to reflect the solar radiation with uniform i ntensity on the PV module receiver system. Silicon solar PV module based CPV system is modeled and sim ulat on is done to study the variation of output power, open-circuit voltage and short-circuit current wi th respect to module temperature and irradiance. These simulation results are experimentally va idated using a CPV (CR ~ 8) system developed in laboratory. The results confirms that the comm erically available silicon solar PV module performs satisfactorily upto ~ 8 Sun concentration.

Research paper thumbnail of Solar Energy From Cells To Grid

Research paper thumbnail of Impact of Potential‐Induced Degradation on Different Architecture‐Based Perovskite Solar Cells

Research paper thumbnail of Investigating the effect of quantized confining energy on the quantum coulomb blockade phenomena in single-electron transistor

Solid State Communications

Research paper thumbnail of Investigating Two-Step MAPbI3 Thin Film Formation during Spin Coating by Simultaneous in Situ Absorption and Photoluminescence Spectroscopy

Journal of Materials Chemistry A

Until today, the two-step processing method represents an attractive route for the thin film form... more Until today, the two-step processing method represents an attractive route for the thin film formation of halide perovskites. However, a fundamental understanding about the film formation dynamics in case of...

Research paper thumbnail of Modeling of four-terminal solar photovoltaic systems for field application

Research paper thumbnail of Graphene oxide-molybdenum oxide composite with improved hole transport in bulk heterojunction solar cells

AIP Advances

Solution processed hole transport layer based on graphene oxide (GO) and molybdenum oxide (MoO 3)... more Solution processed hole transport layer based on graphene oxide (GO) and molybdenum oxide (MoO 3) composite in bulk heterojunction organic solar cell (OSC) devices offer low cost, improved performance compared to conventional organic solar cells. Here, we have made a study comparing the power conversion efficiency (PCE) of this composite to the pristine GO and MoO 3 as a hole transport layer in the organic photovoltaics. The devices with the composite shows optimized performance with PCE of ∼ 5.1%, while the pristine GO and MoO 3 display 1.59% and 2.5%, respectively. These differences are attributed to the lower short circuit current (Jsc) and thereby lower fill factor (FF) with respect to the GO and MoO 3. Nevertheless, the composite based devices exhibits improved optical absorption and photoluminescence quenching as compared to pristine interface layer. This study intends to highlight efficient modulation of the interface barrier of hole transport layer which allow us to give faster transport and extraction of the charge carrier efficiently at the electrodes.

Research paper thumbnail of Potential‐Induced Degradation and Recovery of Perovskite Solar Cells

Solar RRL

This study has received funding from the project PV OpMaat, financed by the cross border collabor... more This study has received funding from the project PV OpMaat, financed by the cross border collaboration program Interreg V Flanders-Netherlands with financial support of the European Funds for Regional Development. B.C. is a postdoctoral fellow of the Research Fund Flanders (FWO).

Research paper thumbnail of Study of transport and recombination mechanism in hole transporter free perovskite solar cell

Materials Research Express

Despite advanced research on device structures and processing conditions of perovskite-based sola... more Despite advanced research on device structures and processing conditions of perovskite-based solar cell, many performance aspects are still less understood. The situation becomes more complex in the case of hole transport free (HTM), open-air synthesized solar cell which has an immense potential for low cost and easy fabrication processes. In this work, a correlation between performance deciding parameters with transport and recombination mechanism for the HTM free open-air synthesized perovskite solar cells are studied. The current-voltage response of the fabricated solar cells is not only limited by the phenomenon of transport and recombination but also the injection efficiency of charge carriers. In comparison with the efficient HTM perovskite solar cells, the domination of space charge limited current inside the perovskite layer in HTM free solar cell limits the performance of the device. The interfacial energetic of the active junction i.e. TiO2/perovskite was studied using capacitive analysis that depicts the charge distribution and kinetics in a solar cell. Indeed, the present work illustrates the way to identify the performance limiting parameters in HTM free perovskite solar cell to improve the performance of future devices.

Research paper thumbnail of Estimating various losses in c-Si solar cells subjected to partial shading: insights into J–V performance reduction

Journal of Computational Electronics

This article reports the effect of partial shading (PS) on the electrical output of a solar cell ... more This article reports the effect of partial shading (PS) on the electrical output of a solar cell using the two-diode model. The reduction in electrical performance parameters induced by various recombination losses has been explained for c-Si solar cells under the effect of PS. The PS mainly affects the short-circuit current density ({J}_{\mathrm{SC}})$$(JSC) and efficiency (\eta )$$(η) of the solar cells. {J}_{\mathrm{SC }}$$JSC and \eta η decrease from 37.84 to 5.48 mA \hbox {cm}^{-2}$$cm-2 and from 18.31 to 2%, respectively. Among all the energy losses encountered for PS, spatial relaxation and recombination losses are the dominating factors responsible for the reduction in {J}_{\mathrm{SC}}$$JSC. PC1D and Griddler simulations have been performed to evaluate the effect of front surface and bulk recombination. The PC1D simulated external quantum efficiency is governed by the front and back surface recombination velocity and carrier life time of the charge carriers under PS. The power loss ($${P}_{\mathrm{e}}$$Pe) of {\sim }$$∼ 34% from the emitter region has been determined by resistance analysis in correlation with the recombination in the emitter region of the solar cells under PS.

Research paper thumbnail of Quantum mechanical investigation of optoelectronic properties of gold nanoparticle attached titanium dioxide nanorods for device applications

Journal of Nanoparticle Research

AbstractThis article reports gold nanoparticle (Au-NP) induced absorption enhancement in hydrothe... more AbstractThis article reports gold nanoparticle (Au-NP) induced absorption enhancement in hydrothermally synthesized titanium dioxide nanorods (TiO2-NRs) with a possibility of the deposition of hybrid nanostructures on the transparent substrates. The localized surface plasmon resonance (LSPR) and hot electron transfer behaviour of Au-NPs attached to the TiO2-NRs has been correlated to their photocatalytic response. The photocurrent enhancement observed in amperometric studies has been explained on the basis of excess electron density in the conduction band of TiO2 due to hot electron transfer from the attached Au-NPs (size in the range of 3 to 44 nm). The quantum mechanical calculation of the electron transmission probability from the resonant Au-NP to the conduction band of TiO2-NR has been presented with respect to the wavelength of the incident spectrum. Further, the role of Au-NP size dependent electron work function has been correlated to the electron transmission probability. This study provides a quantum mechanical explanation to the better response of Au-NPs/TiO2-NRs system for photo-catalytic device applications. Graphical abstractᅟ

Research paper thumbnail of Electro-analytical investigation of potential induced degradation in mc-silicon solar cells: case of sodium ion induced inductive loop

Physical chemistry chemical physics : PCCP, Jan 18, 2018

Potential induced degradation of the shunt type (PID-s) in multi-crystalline silicon (mc-Si) sola... more Potential induced degradation of the shunt type (PID-s) in multi-crystalline silicon (mc-Si) solar cells is becoming critical for performance reduction of solar panels in large scale photovoltaic (PV) power plants. In this article PID-s has been investigated by applying high voltage stress on mc-Si solar cells for their degradation and recovery and results have been explained on the basis of DC and AC characterization. The efficiency decreases drastically from 15.7% to 2.9% due to a high voltage stress of -800 V at 85 °C for 48 hours, which is attributed to a reduction in shunt resistance and an increase in depletion and diffusion capacitances. The reduction in electrical performance due to PID-s has been further explained by morphological, structural and elemental analysis. Observed negative capacitance behaviour in impedance spectra of mc-Si solar cells after PID-s has been attributed to structural deformation caused by potential induced migration of sodium ions (Na+) into mc-Si. ...

Research paper thumbnail of {"__content__"=>"Investigating the influence of charge transport on the performance of PTB7:PCBM based organic solar cells.", "sub"=>{"__content__"=>"71"}}

Physical chemistry chemical physics : PCCP, Jan 14, 2018

A key challenge for researchers in the field of organic solar cells (OSCs) is to develop a physic... more A key challenge for researchers in the field of organic solar cells (OSCs) is to develop a physical model for a device that correctly describes the charge carrier transport phenomenon. In this article, an analytical study on the charge carrier transport phenomenon in an OSC is reported, which expresses a balance between free charge carrier generation and recombination in low mobility PTB7:PC71BM blend layers. First, the current density-voltage (J-V) data for the fabricated OSC were extracted from experiments by varying the incident power light intensity (IPL) and then analysis through theoretical simulation was used to quantify the dominant interface recombination parameters limiting the device's performance. It was found that although the generation of free charge carriers increased at higher IPL values, the performance of the device remained low due to poor electrical transport properties which resulted in a considerable accumulation of generated charge carriers in the active ...

Research paper thumbnail of Investigating the Role of Substrate Tin Diffusion on Hematite Based Photoelectrochemical Water Splitting System

Journal of nanoscience and nanotechnology, 2018

Hematite (α-Fe2O3) nanostructures have been extensively studied as photo-anodes for the conversio... more Hematite (α-Fe2O3) nanostructures have been extensively studied as photo-anodes for the conversion of sunlight into chemical fuels by water splitting. A number of factors limit the photo-activity of pristine hematite nanostructures, including poor electrical conductivity and long penetration depth of light. Previous studies have shown that use of tin (Sn) as an n-type dopant can substantially enhance the photoactivity of hematite photoanodes by modifying their morphological, optical and electrical properties. This article presents impedance spectroscopic investigation of interplay between Sn-doping and the photoanode performance for photoelectrochemical water splitting using hematite nanostructure. Mott-Schottky measurements show that the Sn dopant serves as electron donor and increases the donor density of Sn-doped α-Fe2O3 nanostructured layer to 2.39 × 1019 cm-3. Photoelectrochemical impedance spectroscopy shows efficient photogenerated charge transfer from hematite to electrolyte...

Research paper thumbnail of Theoretical maximum performance evaluation of third generation silicon solar cell consisting of nc-Si:H/a-Si:H quantum wells

Superlattices and Microstructures

Abstract The maximum performance of nc-Si:H/a-Si:H quantum well solar cell is theoretically evalu... more Abstract The maximum performance of nc-Si:H/a-Si:H quantum well solar cell is theoretically evaluated by studying the spectral absorption of incident radiation with respect to the number of inserted nc-Si:H quantum well layers. Fundamental intrinsic properties of a-Si:H and nc-Si:H materials reported in literature have been used to evaluate the performance parameters. Enhanced spectral absorption is recorded due to insertion of nc-Si:H quantum well layers in the intrinsic region of a-Si:H solar cell. By inserting 50 QW layers of nc-Si:H in the intrinsic region of the a-Si:H solar cell, the short-circuit current density (J SC ) increases by ∼100% as compared to the baseline whereas the open-circuit voltage (V OC ) decreases by ∼38%. The decrease in V OC is explained on the basis of quasi-Fermi level separation under the illuminated state of solar cell. Theoretical maximum efficiency, having the combined effect of the increase in J SC and decrease in V OC , has increased by ∼24% in comparison with the baseline due to the use of QW as calculated using ideal carrier lifetime value. With a realistic carrier lifetime of the state-of-the-art a-Si:H solar cells, the addition of QWs do not yield any significant gain. From this study, it is concluded that a high carrier lifetime is required to gain a noteworthy benefit from the nc-Si:H/a-Si:H QWs.

Research paper thumbnail of Photo-induced characteristic study of the smallest fullerene fragment, 1,6,7,10-tetramethylfluoranthene as an acceptor

New J. Chem.

In this study, the use of the novel 1,6,7,10-tetramethylfluoranthene as an acceptor in the organi... more In this study, the use of the novel 1,6,7,10-tetramethylfluoranthene as an acceptor in the organic solar cell has been demonstrated.

Research paper thumbnail of Impedance Spectroscopic Investigation of the Degraded Dye-Sensitized Solar Cell due to Ageing

International Journal of Photoenergy

This paper investigates the effect of ageing on the performance of dye-sensitized solar cells (DS... more This paper investigates the effect of ageing on the performance of dye-sensitized solar cells (DSCs). The electrical characterization of fresh and degraded DSCs is done under AM1.5G spectrum and the current density-voltage (J-V) characteristics are analyzed. Short circuit current density (JSC) decreases significantly whereas a noticeable increase in open circuit voltage is observed. These results have been further investigated electroanalytically using electrochemical impedance spectroscopy (EIS). An increase in net resistance results in a lower JSC for the degraded DSC. This decrease in current is mainly due to degradation of TiO2-dye interface, which is observed from light and dark J-V characteristics and is further confirmed by EIS measurements. A reduction in the chemical capacitance of the degraded DSC is observed, which is responsible for the shifting of Fermi level with respect to conduction band edge that further results in an increase of open circuit voltage for the degrade...

Research paper thumbnail of Revealing the correlation between charge carrier recombination and extraction in an organic solar cell under varying illumination intensity

Physical chemistry chemical physics : PCCP, Jan 20, 2017

The design and fabrication of better excitonic solar cells are the need of the hour for futuristi... more The design and fabrication of better excitonic solar cells are the need of the hour for futuristic energy solutions. This designing needs a better understanding of the charge transport properties of excitonic solar cells. One of the popular methods of understanding the charge transport properties is the analysis of the J-V characteristics of a device through theoretical simulation at varied illumination intensity. Herein, a J-V characteristic of a polymer:fullerene based bulk heterojunction (BHJ) organic solar cells (OSCs) of structure ITO/PEDOT:PSS (∼40 nm)/PTB7:PC71BM (∼100 nm)/Al (∼120 nm) is analyzed using one- and two-diode models at varied illumination intensity in the range of 0.1-2.33 Sun. It was found that the double diode model is better with respect to the single diode model and can explain the J-V characteristics of the OSCs correctly. Further, the recombination mechanism is investigated thoroughly and it was observed that fill factor (FF) is in the range of 62.5%-41.4% ...