ajay kumar baranwal - Academia.edu (original) (raw)
Papers by ajay kumar baranwal
Applied Physics Express, 2015
Tandem solar cells with different device architectures utilizing a back contact transparent condu... more Tandem solar cells with different device architectures utilizing a back contact transparent conductive oxide-less bottom electrode (TCO-less tandem DSSC) that has better control of the optical transmission losses incurred by intermediate TCO layers with flexible Pt/tin-doped indium oxide (ITO)-polyethylene terephthalate film as an intermediate layer are reported. The proposed device architecture suppresses the optical loss to a greater extent (around 30%). Sensitizers were ruthenium-based N719 dye in the top electrode, while the newly synthesized phthalocyanine dye (PC25) corresponding to photon harvesting in the near infrared (NIR) region (up to 900 nm) was used in the TCO-less bottom cell. Open circuit voltage (V oc) ; 1.18 V (sum of top cell and bottom cell V oc) justifies the TCO-less tandem DSSC formation.
CHEMSUSCHEM, 2016
Many efforts have been made towards improving perovskite (PVK) solar cell stability, but their th... more Many efforts have been made towards improving perovskite (PVK) solar cell stability, but their thermal stability, particularly at 85 °C (IEC 61646 climate chamber tests), remains a challenge. Outdoors, the installed solar cell temperature can reach up to 85 °C, especially in desert regions, providing sufficient motivation to study the effect of temperature stress at or above this temperature (e.g., 100 °C) to confirm the commercial viability of PVK solar cells for industrial companies. In this work, a three-layer printable HTM-free CH3NH3PbI3 PVK solar cell with a mesoporous carbon back contact and UV-curable sealant was fabricated and tested for thermal stability over 1500 h at 100 °C. Interestingly, the position of the UV-curing glue was found to drastically affect the device stability. The side-sealed cells show high PCE stability and represent a large step toward commercialization of next generation organic–inorganic lead halide PVK solar cells.
Sustainable Energy & Fuels, 2018
Fully non-vacuum processed perovskite solar cells have been demonstrated using cheap inorganic co... more Fully non-vacuum processed perovskite solar cells have been demonstrated using cheap inorganic copper(I) thiocyanate (CuSCN) as an efficient hole transporting layer in conjunction with low temperature processed carbon back electrodes. The CuSCN interlayer attained better energetic matching and assisted the easy release of holes, reducing the observed hysteresis. The fabricated PSC (F-doped SnO 2 glass (FTO)/dense TiO 2 /porous TiO 2 /CH 3 NH 3 PbI 3 /CuSCN/carbon) was able to realize a power conversion efficiency (PCE) of 12.41%, measured under 100 mW cm À2 illumination with a short circuit current density of 18.90 mA cm À2 , an open circuit voltage of 0.95 V and a fill factor of 0.68. An advantageous 68% of the initial PCE was retained for the unencapsulated PSC stored in air in the dark, measured over 4500 h. Although PSCs without a CuSCN interface retain their initial PCE after 185 days of ambient storage and 1000 h of dark thermal stress (85 C), the PCEs of perovskite solar cells with CuSCN undergo significant deterioration.
Energy Technology, 2019
Organic-inorganic CH 3 NH 3 PbI 3-based perovskite solar cells have received significant research... more Organic-inorganic CH 3 NH 3 PbI 3-based perovskite solar cells have received significant research interest; however, thermal stability issue still remains. Carbon-based triple-porous-layer perovskite solar cells without any hole transporting material were selected in order to investigate the internal degradation process by thermal stresses. The sealed perovskite solar cells at 100°C showed stable performance in the power conversion efficiency up to 4500 h, but the degradation was accelerated after that. By analyzing the perovskite solar cells aged for 7000 h at 100°C, the results of energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy suggest that, although Pb, I, and N were sealed inside of the devices, a plenty amount of CH 3 NH 3 + deactivated in the sealant UV-curable adhesive at 100°C, which is the reason of the thermal degradation for the sealed perovskite solar cells.
Organic Electronics, 2020
Solution processed Cesium Tin halide perovskites (CsSnI 3) are inorganic crystal to be explored f... more Solution processed Cesium Tin halide perovskites (CsSnI 3) are inorganic crystal to be explored for thermoelectric applications. Here, we report a novel strategy using an inorganic Y 2 O 3 scaffold to improve the thermoelectric performance. The additional Y 2 O 3 influence the CsSnI 3 crystal growth and favor more conducting behavior with intrinsic defects (Sn 4þ) formation. Therefore, the resulting solution processed composite film Y 2 O 3 /CsSnI 3 show much improved electrical conductivity of ~310 S/cm as compared to ~98 S/cm of pristine CsSnI 3 film. Under the influence of Y 2 O 3 , the resulting phonon scattering path was enhanced significantly due to formed defects/ vacancy and reduced CsSnI 3 crystal size, which showed a reduction in thermal conductivity from 0.74 W/mK to 0.28 W/mK. This work paves a new paradigm to improve the thermoelectric performance of solution based thermoelectric generator.
Journal of Electronic Materials, 2019
Inorganic CsSnI 3 based perovskite crystals are interesting thermoelectric materials, owing to th... more Inorganic CsSnI 3 based perovskite crystals are interesting thermoelectric materials, owing to their unusual electronic properties. Here we report the thermoelectric power performance of a solution-coated CsSnI 3 thin film from the viewpoint of carrier concentration optimizations. It was found that the carrier concentration can be changed by altering the aging time of the precursor solution. X-ray photoelectron spectroscopy analysis showed that the concentration of metallic Sn 4+ increased as the solution aging time increased. This made possible to explore the relationship between carrier concentration and thermoelectric power factor. After controlling Sn 4+ concentrations, we report a power factor of 145.10 lW m À1 K À2 , along with electrical conductivity 106 S/cm and Seebeck coefficient of 117 lV/K, measured at room temperature.
ACS Applied Energy Materials, 2022
The oxidation of tin halide perovskite precursor (THP) with the solvent dimethyl sulfoxide (DMSO)... more The oxidation of tin halide perovskite precursor (THP) with the solvent dimethyl sulfoxide (DMSO) has intriguing drawbacks. We found that THP oxidation under progressive stirring can be hindered by the addition of GeI 2. Subsequently, the stirring time of the precursor solution affects the carrier density and semiconducting properties of fabricated films, because DMSO can increase the oxidation induced carrier density. On the other hand, dimethylformamide (DMF) can suppress the oxidation induced carrier density. After 24 h, an efficiency of 10.26% is found when DMF is used and 7.12% is found when DMSO is used as a stirring solvent.
ACS Applied Energy Materials, 2022
Tin halide perovskites (THPs) have appealing optoelectronic properties similar to lead halide per... more Tin halide perovskites (THPs) have appealing optoelectronic properties similar to lead halide perovskites (LHPs). However, THPs coated on metal oxide electrodes in normal-structure perovskite solar cells exhibit poor diode rectification, resulting in poor efficiency. This poor photoelectric performance in n−i−p-based THP solar cells is in contrast with LHP solar cells. We report that this deficient performance of THP solar cells is triggered by the defect states of the metal oxide layer. The defect states of the metal oxide can trap the electrons from the THP, leading to the prompt formation of Sn(IV), which will increase the carrier density and lead to poor photoelectric performance. This observation was supported by the ultraviolet-photoelectron spectroscopic measurements of inorganic thin films Al 2 O 3 , SnO 2 , TiO 2 , ZnO, and ZrO 2. However, this self-doping phenomenon resulting in the increase in carrier density can be applied to thermoelectric studies. Using CsSnI 3 /ZrO 2 nanocomposites as thermoelectric active layers, we report a power factor of 186.58 μW/mK 2 measured at room temperature, which is better than the 148.61 μW/mK 2 of the original CsSnI 3 thin film.
Nanomaterials, 2022
The excellent optoelectronic properties of tin halide perovskites (Sn-PVKs) have made them a prom... more The excellent optoelectronic properties of tin halide perovskites (Sn-PVKs) have made them a promising candidate for replacing toxic Pb counterparts. Concurrently, their enormous potential in photon harvesting and thermoelectricity applications has attracted increasing attention. The optoelectronic properties of Sn-PVKs are governed by the flexible nature of SnI6 octahedra, and they exhibit extremely low thermal conductivity. Due to these diverse applications, this review first analyzes the structural properties, optoelectronic properties, defect physics, and thermoelectric properties of Sn-PVKs. Then, recent techniques developed to solve limitations with Sn-PVK-based devices to improve their photoelectric and thermoelectric performance are discussed in detail. Finally, the challenges and prospects for further development of Sn-PVK-based devices are discussed.
![Research paper thumbnail of Enhanced Electron Transport in Heterojunction Sn-Perovskite Solar Cells Assisted by [6,6]-Phenyl-C61-butyric Acid Methyl Ester as a Dopant](https://attachments.academia-assets.com/118632344/thumbnails/1.jpg)
](ACS Energy Letters, 2024
Tin halide perovskite (THP) possesses p-type semiconducting properties owing to innate Sn oxidati... more Tin halide perovskite (THP) possesses p-type semiconducting properties owing to innate Sn oxidative defect states. These defect states create imbalance in charge collection at the interfaces, which hinders overall solar cell efficiency. To effectively harness THP’s potential, we introduced a strategic n-type commonly used material, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), as a dopant, which has rarely been discussed. The coupling of PCBM and THP, validated through experimental and density functional theory methods, effectively targeted Sn defect states and transformed the THP semiconducting nature from p-type to intrinsic. Furthermore, strategically positioned PCBM at the grain boundaries offered multiple benefits, including improved adhesion between grains, leading to reduced lattice strain, enhanced energetic matching, and efficient charge transfer. This positing effectively harnessed electron collection due to PCBM’s n-type electronic properties, leading to an enhanced PCE. This blend strategy, broadly followed in organic solar cells, led to the development of PCBM-THP heterojunction solar cells, achieving a record efficiency of 12.68%.
Journal of Physical Chemistry Letters, Mar 31, 2022
Overcoming Voc loss to increase the efficiency of perovskite solar cells (PSCs) has been aggressi... more Overcoming Voc loss to increase the efficiency of perovskite solar cells (PSCs) has been aggressively studied. In this work, we introduce and compare rubidium iodide (RbI) and potassium iodide (KI) alkali metal halides (AMHs) as dopants in a tin-lead (SnPb)-based perovskite system to improve the performance of PSCs by enhancing their Voc. Improvement in terms of surface morphology, crystallinity, charge transfer, and carrier transport in the SnPb perovskites was observed with the addition of AMH dopants. Significant power conversion efficiency improvement has been achieved with the incorporation of either dopant, and the highest efficiency was 21.04% in SnPb mixed halide PSCs when the RbI dopant was employed. In conclusion, we can outline the enhancement strategy that yields a remarkable efficiency of >20% with a smaller Voc loss and improved storage, light, and thermal stability in SnPb PSCs via doping engineering.
Applied Physics Express, Mar 1, 2023
Nano Convergence, Sep 22, 2017
Research of CH 3 NH 3 PbI 3 perovskite solar cells had significant attention as the candidate of ... more Research of CH 3 NH 3 PbI 3 perovskite solar cells had significant attention as the candidate of new future energy. Due to the toxicity, however, lead (Pb) free photon harvesting layer should be discovered to replace the present CH 3 NH 3 PbI 3 perovskite. In place of lead, we have tried antimony (Sb) and bismuth (Bi) with organic and metal monovalent cations (CH 3 NH 3 + , Ag + and Cu +). Therefore, in this work, lead-free photo-absorber layers of (CH 3 NH 3) 3 Bi 2 I 9 , (CH 3 NH 3) 3 Sb 2 I 9 , (CH 3 NH 3) 3 SbBiI 9 , Ag 3 BiI 6 , Ag 3 BiI 3 (SCN) 3 and Cu 3 BiI 6 were processed by solution deposition way to be solar cells. About the structure of solar cells, we have compared the normal (n-i-p: TiO 2-perovskite-spiro OMeTAD) and inverted (p-in: NiO-perovskite-PCBM) structures. The normal (n-i-p)-structured solar cells performed better conversion efficiencies, basically. But, these environmental friendly photon absorber layers showed the uneven surface morphology with a particular grow pattern depend on the substrate (TiO 2 or NiO). We have considered that the unevenness of surface morphology can deteriorate the photovoltaic performance and can hinder future prospect of these lead-free photon harvesting layers. However, we found new interesting finding about the progress of devices by the interface of NiO/ Sb 3+ and TiO 2 /Cu 3 BiI 6 , which should be addressed in the future study.
The Japan Society of Applied Physics, Feb 3, 2017
2017 24th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD), 2017
We developed lead-free perovskite solar cells, because lead is harmful to the human body. In this... more We developed lead-free perovskite solar cells, because lead is harmful to the human body. In this study, the lead-free perovskite layers were fabricated using antimony, bismuth and silver. Normal (n-i-p) and inverse (p-i-n) structures were tried for the solar cells. By using a lead-free perovskite with silver and bismuth for the normal structure, conversion efficiency of 0.892% was achieved.
The Japan Society of Applied Physics, Jan 26, 2021
Advanced Functional Materials, Apr 26, 2023
This study is on the enhancement of the efficiency of wide bandgap (FA0.8Cs0.2PbI1.8Br1.2) perovs... more This study is on the enhancement of the efficiency of wide bandgap (FA0.8Cs0.2PbI1.8Br1.2) perovskite solar cells (PSCs) used as the top layer of the perovskite/perovskite tandem solar cell. Poly[bis(4‐phenyl) (2,4,6‐trimethylphenyl) amine] (PTAA) and the monomolecular layer called SAM layer are effective hole collection layers for APbI3 PSCs. However, these hole transport layers (HTL) do not give high efficiencies for the wide bandgap FA0.8Cs0.2PbI1.8Br1.2 PSCs. It is found that the surface‐modified PTAA by monomolecular layer (MNL) improves the efficiency of PSCs. The improved efficiency is explained by the improved FA0.8Cs0.2PbI1.8Br1.2 film quality, decreased film distortion (low lattice disordering) and low density of the charge recombination site, and improves carrier collection by the surface modified PTAA layer. In addition, the relationship between the length of the alkyl group linking the anchor group and the carbazole group is also discussed. Finally, the wide bandgap lead PSCs (Eg = 1.77 eV) fabricated on the PTAA/monomolecular bilayer give a higher power conversion efficiency of 16.57%. Meanwhile, all‐perovskite tandem solar cells with over 25% efficiency are reported by using the PTAA/monomolecular substrate.
The Japan Society of Applied Physics, Jan 26, 2021
Physica Status Solidi A-applications and Materials Science, Jul 25, 2023
Applied Physics Express, 2015
Tandem solar cells with different device architectures utilizing a back contact transparent condu... more Tandem solar cells with different device architectures utilizing a back contact transparent conductive oxide-less bottom electrode (TCO-less tandem DSSC) that has better control of the optical transmission losses incurred by intermediate TCO layers with flexible Pt/tin-doped indium oxide (ITO)-polyethylene terephthalate film as an intermediate layer are reported. The proposed device architecture suppresses the optical loss to a greater extent (around 30%). Sensitizers were ruthenium-based N719 dye in the top electrode, while the newly synthesized phthalocyanine dye (PC25) corresponding to photon harvesting in the near infrared (NIR) region (up to 900 nm) was used in the TCO-less bottom cell. Open circuit voltage (V oc) ; 1.18 V (sum of top cell and bottom cell V oc) justifies the TCO-less tandem DSSC formation.
CHEMSUSCHEM, 2016
Many efforts have been made towards improving perovskite (PVK) solar cell stability, but their th... more Many efforts have been made towards improving perovskite (PVK) solar cell stability, but their thermal stability, particularly at 85 °C (IEC 61646 climate chamber tests), remains a challenge. Outdoors, the installed solar cell temperature can reach up to 85 °C, especially in desert regions, providing sufficient motivation to study the effect of temperature stress at or above this temperature (e.g., 100 °C) to confirm the commercial viability of PVK solar cells for industrial companies. In this work, a three-layer printable HTM-free CH3NH3PbI3 PVK solar cell with a mesoporous carbon back contact and UV-curable sealant was fabricated and tested for thermal stability over 1500 h at 100 °C. Interestingly, the position of the UV-curing glue was found to drastically affect the device stability. The side-sealed cells show high PCE stability and represent a large step toward commercialization of next generation organic–inorganic lead halide PVK solar cells.
Sustainable Energy & Fuels, 2018
Fully non-vacuum processed perovskite solar cells have been demonstrated using cheap inorganic co... more Fully non-vacuum processed perovskite solar cells have been demonstrated using cheap inorganic copper(I) thiocyanate (CuSCN) as an efficient hole transporting layer in conjunction with low temperature processed carbon back electrodes. The CuSCN interlayer attained better energetic matching and assisted the easy release of holes, reducing the observed hysteresis. The fabricated PSC (F-doped SnO 2 glass (FTO)/dense TiO 2 /porous TiO 2 /CH 3 NH 3 PbI 3 /CuSCN/carbon) was able to realize a power conversion efficiency (PCE) of 12.41%, measured under 100 mW cm À2 illumination with a short circuit current density of 18.90 mA cm À2 , an open circuit voltage of 0.95 V and a fill factor of 0.68. An advantageous 68% of the initial PCE was retained for the unencapsulated PSC stored in air in the dark, measured over 4500 h. Although PSCs without a CuSCN interface retain their initial PCE after 185 days of ambient storage and 1000 h of dark thermal stress (85 C), the PCEs of perovskite solar cells with CuSCN undergo significant deterioration.
Energy Technology, 2019
Organic-inorganic CH 3 NH 3 PbI 3-based perovskite solar cells have received significant research... more Organic-inorganic CH 3 NH 3 PbI 3-based perovskite solar cells have received significant research interest; however, thermal stability issue still remains. Carbon-based triple-porous-layer perovskite solar cells without any hole transporting material were selected in order to investigate the internal degradation process by thermal stresses. The sealed perovskite solar cells at 100°C showed stable performance in the power conversion efficiency up to 4500 h, but the degradation was accelerated after that. By analyzing the perovskite solar cells aged for 7000 h at 100°C, the results of energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy suggest that, although Pb, I, and N were sealed inside of the devices, a plenty amount of CH 3 NH 3 + deactivated in the sealant UV-curable adhesive at 100°C, which is the reason of the thermal degradation for the sealed perovskite solar cells.
Organic Electronics, 2020
Solution processed Cesium Tin halide perovskites (CsSnI 3) are inorganic crystal to be explored f... more Solution processed Cesium Tin halide perovskites (CsSnI 3) are inorganic crystal to be explored for thermoelectric applications. Here, we report a novel strategy using an inorganic Y 2 O 3 scaffold to improve the thermoelectric performance. The additional Y 2 O 3 influence the CsSnI 3 crystal growth and favor more conducting behavior with intrinsic defects (Sn 4þ) formation. Therefore, the resulting solution processed composite film Y 2 O 3 /CsSnI 3 show much improved electrical conductivity of ~310 S/cm as compared to ~98 S/cm of pristine CsSnI 3 film. Under the influence of Y 2 O 3 , the resulting phonon scattering path was enhanced significantly due to formed defects/ vacancy and reduced CsSnI 3 crystal size, which showed a reduction in thermal conductivity from 0.74 W/mK to 0.28 W/mK. This work paves a new paradigm to improve the thermoelectric performance of solution based thermoelectric generator.
Journal of Electronic Materials, 2019
Inorganic CsSnI 3 based perovskite crystals are interesting thermoelectric materials, owing to th... more Inorganic CsSnI 3 based perovskite crystals are interesting thermoelectric materials, owing to their unusual electronic properties. Here we report the thermoelectric power performance of a solution-coated CsSnI 3 thin film from the viewpoint of carrier concentration optimizations. It was found that the carrier concentration can be changed by altering the aging time of the precursor solution. X-ray photoelectron spectroscopy analysis showed that the concentration of metallic Sn 4+ increased as the solution aging time increased. This made possible to explore the relationship between carrier concentration and thermoelectric power factor. After controlling Sn 4+ concentrations, we report a power factor of 145.10 lW m À1 K À2 , along with electrical conductivity 106 S/cm and Seebeck coefficient of 117 lV/K, measured at room temperature.
ACS Applied Energy Materials, 2022
The oxidation of tin halide perovskite precursor (THP) with the solvent dimethyl sulfoxide (DMSO)... more The oxidation of tin halide perovskite precursor (THP) with the solvent dimethyl sulfoxide (DMSO) has intriguing drawbacks. We found that THP oxidation under progressive stirring can be hindered by the addition of GeI 2. Subsequently, the stirring time of the precursor solution affects the carrier density and semiconducting properties of fabricated films, because DMSO can increase the oxidation induced carrier density. On the other hand, dimethylformamide (DMF) can suppress the oxidation induced carrier density. After 24 h, an efficiency of 10.26% is found when DMF is used and 7.12% is found when DMSO is used as a stirring solvent.
ACS Applied Energy Materials, 2022
Tin halide perovskites (THPs) have appealing optoelectronic properties similar to lead halide per... more Tin halide perovskites (THPs) have appealing optoelectronic properties similar to lead halide perovskites (LHPs). However, THPs coated on metal oxide electrodes in normal-structure perovskite solar cells exhibit poor diode rectification, resulting in poor efficiency. This poor photoelectric performance in n−i−p-based THP solar cells is in contrast with LHP solar cells. We report that this deficient performance of THP solar cells is triggered by the defect states of the metal oxide layer. The defect states of the metal oxide can trap the electrons from the THP, leading to the prompt formation of Sn(IV), which will increase the carrier density and lead to poor photoelectric performance. This observation was supported by the ultraviolet-photoelectron spectroscopic measurements of inorganic thin films Al 2 O 3 , SnO 2 , TiO 2 , ZnO, and ZrO 2. However, this self-doping phenomenon resulting in the increase in carrier density can be applied to thermoelectric studies. Using CsSnI 3 /ZrO 2 nanocomposites as thermoelectric active layers, we report a power factor of 186.58 μW/mK 2 measured at room temperature, which is better than the 148.61 μW/mK 2 of the original CsSnI 3 thin film.
Nanomaterials, 2022
The excellent optoelectronic properties of tin halide perovskites (Sn-PVKs) have made them a prom... more The excellent optoelectronic properties of tin halide perovskites (Sn-PVKs) have made them a promising candidate for replacing toxic Pb counterparts. Concurrently, their enormous potential in photon harvesting and thermoelectricity applications has attracted increasing attention. The optoelectronic properties of Sn-PVKs are governed by the flexible nature of SnI6 octahedra, and they exhibit extremely low thermal conductivity. Due to these diverse applications, this review first analyzes the structural properties, optoelectronic properties, defect physics, and thermoelectric properties of Sn-PVKs. Then, recent techniques developed to solve limitations with Sn-PVK-based devices to improve their photoelectric and thermoelectric performance are discussed in detail. Finally, the challenges and prospects for further development of Sn-PVK-based devices are discussed.
ACS Energy Letters, 2024
Tin halide perovskite (THP) possesses p-type semiconducting properties owing to innate Sn oxidati... more Tin halide perovskite (THP) possesses p-type semiconducting properties owing to innate Sn oxidative defect states. These defect states create imbalance in charge collection at the interfaces, which hinders overall solar cell efficiency. To effectively harness THP’s potential, we introduced a strategic n-type commonly used material, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), as a dopant, which has rarely been discussed. The coupling of PCBM and THP, validated through experimental and density functional theory methods, effectively targeted Sn defect states and transformed the THP semiconducting nature from p-type to intrinsic. Furthermore, strategically positioned PCBM at the grain boundaries offered multiple benefits, including improved adhesion between grains, leading to reduced lattice strain, enhanced energetic matching, and efficient charge transfer. This positing effectively harnessed electron collection due to PCBM’s n-type electronic properties, leading to an enhanced PCE. This blend strategy, broadly followed in organic solar cells, led to the development of PCBM-THP heterojunction solar cells, achieving a record efficiency of 12.68%.
Journal of Physical Chemistry Letters, Mar 31, 2022
Overcoming Voc loss to increase the efficiency of perovskite solar cells (PSCs) has been aggressi... more Overcoming Voc loss to increase the efficiency of perovskite solar cells (PSCs) has been aggressively studied. In this work, we introduce and compare rubidium iodide (RbI) and potassium iodide (KI) alkali metal halides (AMHs) as dopants in a tin-lead (SnPb)-based perovskite system to improve the performance of PSCs by enhancing their Voc. Improvement in terms of surface morphology, crystallinity, charge transfer, and carrier transport in the SnPb perovskites was observed with the addition of AMH dopants. Significant power conversion efficiency improvement has been achieved with the incorporation of either dopant, and the highest efficiency was 21.04% in SnPb mixed halide PSCs when the RbI dopant was employed. In conclusion, we can outline the enhancement strategy that yields a remarkable efficiency of >20% with a smaller Voc loss and improved storage, light, and thermal stability in SnPb PSCs via doping engineering.
Applied Physics Express, Mar 1, 2023
Nano Convergence, Sep 22, 2017
Research of CH 3 NH 3 PbI 3 perovskite solar cells had significant attention as the candidate of ... more Research of CH 3 NH 3 PbI 3 perovskite solar cells had significant attention as the candidate of new future energy. Due to the toxicity, however, lead (Pb) free photon harvesting layer should be discovered to replace the present CH 3 NH 3 PbI 3 perovskite. In place of lead, we have tried antimony (Sb) and bismuth (Bi) with organic and metal monovalent cations (CH 3 NH 3 + , Ag + and Cu +). Therefore, in this work, lead-free photo-absorber layers of (CH 3 NH 3) 3 Bi 2 I 9 , (CH 3 NH 3) 3 Sb 2 I 9 , (CH 3 NH 3) 3 SbBiI 9 , Ag 3 BiI 6 , Ag 3 BiI 3 (SCN) 3 and Cu 3 BiI 6 were processed by solution deposition way to be solar cells. About the structure of solar cells, we have compared the normal (n-i-p: TiO 2-perovskite-spiro OMeTAD) and inverted (p-in: NiO-perovskite-PCBM) structures. The normal (n-i-p)-structured solar cells performed better conversion efficiencies, basically. But, these environmental friendly photon absorber layers showed the uneven surface morphology with a particular grow pattern depend on the substrate (TiO 2 or NiO). We have considered that the unevenness of surface morphology can deteriorate the photovoltaic performance and can hinder future prospect of these lead-free photon harvesting layers. However, we found new interesting finding about the progress of devices by the interface of NiO/ Sb 3+ and TiO 2 /Cu 3 BiI 6 , which should be addressed in the future study.
The Japan Society of Applied Physics, Feb 3, 2017
2017 24th International Workshop on Active-Matrix Flatpanel Displays and Devices (AM-FPD), 2017
We developed lead-free perovskite solar cells, because lead is harmful to the human body. In this... more We developed lead-free perovskite solar cells, because lead is harmful to the human body. In this study, the lead-free perovskite layers were fabricated using antimony, bismuth and silver. Normal (n-i-p) and inverse (p-i-n) structures were tried for the solar cells. By using a lead-free perovskite with silver and bismuth for the normal structure, conversion efficiency of 0.892% was achieved.
The Japan Society of Applied Physics, Jan 26, 2021
Advanced Functional Materials, Apr 26, 2023
This study is on the enhancement of the efficiency of wide bandgap (FA0.8Cs0.2PbI1.8Br1.2) perovs... more This study is on the enhancement of the efficiency of wide bandgap (FA0.8Cs0.2PbI1.8Br1.2) perovskite solar cells (PSCs) used as the top layer of the perovskite/perovskite tandem solar cell. Poly[bis(4‐phenyl) (2,4,6‐trimethylphenyl) amine] (PTAA) and the monomolecular layer called SAM layer are effective hole collection layers for APbI3 PSCs. However, these hole transport layers (HTL) do not give high efficiencies for the wide bandgap FA0.8Cs0.2PbI1.8Br1.2 PSCs. It is found that the surface‐modified PTAA by monomolecular layer (MNL) improves the efficiency of PSCs. The improved efficiency is explained by the improved FA0.8Cs0.2PbI1.8Br1.2 film quality, decreased film distortion (low lattice disordering) and low density of the charge recombination site, and improves carrier collection by the surface modified PTAA layer. In addition, the relationship between the length of the alkyl group linking the anchor group and the carbazole group is also discussed. Finally, the wide bandgap lead PSCs (Eg = 1.77 eV) fabricated on the PTAA/monomolecular bilayer give a higher power conversion efficiency of 16.57%. Meanwhile, all‐perovskite tandem solar cells with over 25% efficiency are reported by using the PTAA/monomolecular substrate.
The Japan Society of Applied Physics, Jan 26, 2021
Physica Status Solidi A-applications and Materials Science, Jul 25, 2023