Deb K U M A R Shah, PhD | Chonbuk National University (original) (raw)

Papers by Deb K U M A R Shah, PhD

Inorganics, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Electrochem

The impact of doping concentration and thickness of n-InGaN and p-InGaN regions on the power conv... more The impact of doping concentration and thickness of n-InGaN and p-InGaN regions on the power conversion efficiency of single junction-based InGaN solar cells was studied by the Silvaco ATLAS simulation software. The doping concentration 5 × 1019 cm−3 and 1 × 1015 cm−3 were optimized for n-InGaN and p-InGaN regions, respectively. The thickness of 300 nm was optimized for both n-InGaN and p-InGaN regions. The highest efficiency of 22.17% with Jsc = 37.68 mA/cm2, Voc = 0.729 V, and FF = 80.61% was achieved at optimized values of doping concentration and thickness of n-InGaN and p-InGaN regions of InGaN solar cells. The simulation study shows the relevance of the Silvaco ATLAS simulation tool, as well as the optimization of doping concentration and thickness of n- and p-InGaN regions for solar cells, which would make the development of high-performance InGaN solar cells low-cost and efficient.

Electrochem, 2022

Materials Science in Semiconductor Processing, 2022

This work describes the thickness optimization of graphene oxide (GO) as an antireflection coatin... more This work describes the thickness optimization of graphene oxide (GO) as an antireflection coating (ARC) layer using a low-cost deposition process and validates the experimental results by a simulation study. The optimization of GO thickness was carried out by varying the speed of the spin coating and characterized by various characterization tools. It was found that GO ARC of thickness 80 nm was optimized having the lowest average reflectance of ~7.69% which was lowered to other GO thicknesses. In a simulation study, the different GO thicknesses were selected as input parameters to explore the highest photovoltaic performances of Si solar cells. The Si solar cell with the GO thickness of 80 nm expressed the highest short-circuit current (I sc = 3.42 A), opencircuit voltage (V oc = 0.653 V), power conversion efficiency (18.78%), and FF (83.74%). The photovoltaic (PV) parameters such as I sc , V oc , FF, efficiency, and sheet resistance were characterized by varying the thickness of ARC layer at the junction depth range from 0.1 μm to 0.5 μm for Si solar cells. It was been found that the optimized thickness (80 nm) of the GO ARC layer exhibited high performance, photocurrent, external quantum efficiency (EQE) of 95%, and high generation of charge carriers. This simulation on optimizing the GO thickness for Si solar cells would provide the utilization of low-cost GO ARC for the development of high-performance Si solar cells.

Journal of Electronic Materials, 2022

The heterojunction (HJ) solar cell is one of the best possible options to upgrade the conventiona... more The heterojunction (HJ) solar cell is one of the best possible options to upgrade the conventional single homo-junction c-Si solar cell. In this work, a single HJ solar cell based on crystalline silicon (c-Si) wafer with zinc oxide (ZnO) is designed to reduce the loss of power conversion owing to the reflection of incident photons by the top surface of silicon. A PC1D simulation is used to evaluate the optimum numerical value of key photovoltaic parameters for HJ-based c-Si solar cells. The average reflectance for ZnO/Si HJ-based c-Si is 7.65% in the wavelength range of 400-1000 nm. The highest efficiency (η = 24.8%) of the ZnO/Si HJ-based c-Si solar is obtained with a 400 μm base thickness, 20 μm emitter thickness, doping concentration of 1.1 × 1017 cm−3 in the base and a doping concentration of 5.1 x 1016 cm−3 in the emitter. The proposed ZnO/Si HJ-based c-Si solar cell with high efficiency would be one of the best possible alternative HJ device to the conventional single homo-junction c-Si solar cell.

Conference, 2019

The crystalline silicon (Si) solar cells are highly renowned photovoltaic technology and well-est... more The crystalline silicon (Si) solar cells are highly renowned photovoltaic technology and well-established as commercial solar technology. Most solar panels are globally installed with crystalline Si solar modules. In the present scenario, more than 90% global photovoltaic (PV) market is shared by c-Si solar cells, but the cost of c-Si panels is still very high as compared with the other PV technology. To reduce the cost of Si solar panels, a few necessary steps such as low-cost Si manufacturing, cheap antireflection coating materials, inexpensive solar panel manufacturing are to be considered. It is known that the antireflection (AR) layer in a c-Si solar cell is one of the important components to reduce Fresnel reflection for improving the overall conversion efficiency. The reflection behavior in Si wafer is normally possessed two major intrinsic drawbacks; i) the spectral mismatch loss and ii) the high Fresnel reflection loss due to the high contrast of refractive indices between air and silicon wafer. In recent years, researchers and scientists are highly devoted a lot of research in the field of searching effective and low-cost AR materials. SiNx is well-known AR material in commercial c-Si solar cells due to its good deposition and interaction with passivated Si surfaces. However, the deposition of SiNx AR is usually performed by an expensive PECVD process which could have several demerits like difficult handling and damaging the Si substrate by plasma when secondary electrons collide with the wafer surface for AR coating. It is very important to explore new, low cost and effective AR deposition processes to cut the manufacturing cost of c-Si solar cells. One can also be realized that a nano-texturing process like the growth of nanowires, nanorods, nanopyramids, nanopillars, etc. on Si wafer can provide a low reflection on the surface of Si wafer-based solar cells. In this work, we report on the development of crystalline Si solar cells without using the ARC layer. The Silicon wafer was modified by growing nanowires like Si nanostructures using the wet controlled etching method and directly used for the fabrication of Si solar cells without AR. The nanostructures over the Si wafer were optimized in terms of sizes, lengths, and densities by changing the etching conditions. Well-defined and aligned wires like structures were achieved when the etching time is 20 to 30 min. The prepared Si nanostructured displayed the minimum reflectance of ~1.64% at 850 nm with the average reflectance of ~2.25% in the wavelength range from 400-1000 nm. The nanostructured Si wafer-based solar cells achieved comparable power conversion efficiency in comparison with c-Si solar cells with SiNx AR layer. From this study, it is confirmed that the reported method (controlled wet etching) is an easy, facile method for the preparation of nanostructured like wires on Si wafer with low reflectance in the whole visible region, which has greater prospects in developing c-Si solar cells without AR layer at low cost.

Solar energy, 2022

This paper reports on the computational study to investigate the high-performance gallium arsenid... more This paper reports on the computational study to investigate the high-performance gallium arsenide (GaAs) solar cells based on the Al 2 O 3 antireflection coating (ARC) layer by optimizing the carrier lifetime, doping concentration, energy bandgap, thickness of window and absorber layers. In this simulation, the parameters like GaAs as an absorber layer, CdS as a window layer, and fixed thickness of the Al 2 O 3 ARC layer were selected for performing the personal computer one dimensional (PC1D) simulation. As compared to GaAs solar cell with no ARC layer, GaAs solar cell with Al 2 O 3 ARC layer (90 nm) presented the high power conversion efficiency (PCE) of 24.60% at absorber thickness 6 μm and 30 nm for window layer. The optimized values of carrier lifetime and doping concentration for high PCE were found to be 100 μs and 1 × 10 17 cm − 3 for both absorber and window layers, respectively. The V oc , PCE, and fill factor (FF) values gradually increased with the increase of carrier lifetime and doping concentration of the CdS window layer. At optimized parameters, the highest value of I sc = 3.11 A, V oc = 0.884 V and PCE = 24.60% were achieved by GaAs solar cells with Al 2 O 3 ARC layer. This study proves that optimization of CdS window layer through carrier lifetime, thickness, doping concentrations, and bandgap, etc. would make the crucial component to manufacture cost-effective, high-performance GaAs solar cells based on Al 2 O 3 ARC layer.

Journal of Advanced Research in Dynamical and Control Systems, 2020

Improving the overall performance of the PV cell can play crucial role to the total generated pho... more Improving the overall performance of the PV cell can play crucial role to the total generated photovoltaic power worldwide. An efficient window layer is essential to check the front surface recombination in the solar cell. In this paper, we explored InGaP window layer for GaAs solar cell and analyzed performance with the help of PC1D simulation software. For this, we have varied thickness and doping level of InGaP window layer and performance of the solar cell has been examined with the help of current-voltage (I-V) characteristics. We also reviewed the effect of temperature on the performance of the solar cell. It has been found that the short circuit current 3.192 A, open circuit voltage 0.8959 V and power conversion efficiency 25.78% of InGaP/GaAs solar cell at window layer thickness 30 nm with doping level 1.00E+17cm 3 .

Engineered Science, 2021

The purpose of providing an anti-reflection coating (ARC) layer on the surface of crystalline sil... more The purpose of providing an anti-reflection coating (ARC) layer on the surface of crystalline silicon (c-Si) solar cells is to stipulate a unique dielectric material medium that causes destructive interference of the reflected light from device surfaces and minimize the reflection of light, which can enhance the optoelectrical properties. The optimization of thickness of niobium pentoxide (Nb2O5) as an ARC layer using a low-cost, sol-gel spin coating deposition process for the high photovoltaic performance of the c-Si solar cell using a PC1D simulation study. The lowest average reflectance of ~7.21% was achieved at 75 nm thickness of the ARC layer in comparison to others. In a simulation, the different value of thicknesses of the ARC layers was selected as input parameters to explore the photovoltaic characteristics of c-Si solar cells. The simulated results show that the highest power conversion efficiency (PCE) of 17.92% and more than 95% external quantum efficiency (EQE) at 75 nm thickness of ARC layer. This work on the optimization of thicknesses of the ARC layer would provide the utilization of low-cost Nb2O5 ARC layer-based for the development of high-performance c-Si solar cells.

This paper reports the optimization of zinc selenide as a window layer for GaAs solar cells in te... more This paper reports the optimization of zinc selenide as a window layer for GaAs solar cells in terms of thickness, carrier concentration, and bandgap of the material. Zinc selenide has been chosen for the window layer for appropriate front surface combination with absorber layer for the best performance in GaAs solar cell. The characteristics like current-power curve and efficiency have been analyzed by the PC1D modeling tool by varying different parameters like thickness, carrier concentration, and bandgap of window layer. The short-circuit current of 3.2 A, open-circuit voltage of 0.871 V, and the highest power conversion efficiency of 24.55% of solar cell has been observed at the thickness of 50 nm of the window layer. The electron and hole densities have been observed 1.1 Â 10 16 cm À3 and 1 Â 10 15 cm À3 respectively at distance from front in the range from 0 lm to 5 lm. The highest power conversion efficiency of 24.26% has been achieved at carrier concentration 1 Â 10 16 cm À3...

Engineered Science, 2021

Journal of Electronic materials, 2021

Materials Today: Proceedings, 2021

Journal of Advanced Research in Dynamical and Control Systems, 2020

Coatings, Sep 30, 2019

Mn 2 O 3 nanomaterials have been recently composing a variety of electrochemical systems like fue... more Mn 2 O 3 nanomaterials have been recently composing a variety of electrochemical systems like fuel cells, supercapacitors, etc., due to their high specific capacitance, low cost, abundance and environmentally benign nature. In this work, mesoporous Mn 2 O 3 nanoparticles (NPs) were synthesized by manganese acetate, citric acid and sodium hydroxide through a hydrothermal process at 150 • C for 3 h. The synthesized mesoporous Mn 2 O 3 NPs were thoroughly characterized in terms of their morphology, surfaces, as well as their crystalline, electrochemical and electrochemical properties. For supercapacitor applications, the synthesized mesoporous Mn 2 O 3 NP-based electrode accomplished an excellent specific capacitance (C sp) of 460 F•g −1 at 10 mV•s −1 with a good electrocatalytic activity by observing good electrochemical properties in a 6 M KOH electrolyte. The excellent C sp might be explained by the improvement of the surface area, porous surface and uniformity, which might favor the generation of large active sites and a fast ionic transport over the good electrocatalytic surface of the Mn 2 O 3 electrode. The fabricated supercapacitors exhibited a good cycling stability after 5000 cycles by maintaining~83% of C sp .

Applied Sciences

This paper describes the unique antireflection (AR) layer of vertically arranged ZnO nanorods (NR... more This paper describes the unique antireflection (AR) layer of vertically arranged ZnO nanorods (NRs) on crystalline silicon (c-Si) solar cells and studies the charge transport and photovoltaic properties by simulation. The vertically arranged ZnO NRs were deposited on ZnO-seeded c-Si wafers by a simple low-temperature solution process. The lengths of the ZnO NRs were optimized by changing the reaction times. Highly dense and vertically arranged ZnO NRs were obtained over the c-Si wafer when the reaction time was 5 h. The deposited ZnO NRs on the c-Si wafers exhibited the lowest reflectance of ~7.5% at 838 nm, having a reasonable average reflectance of ~9.5% in the whole wavelength range (400–1000 nm). Using PC1D software, the charge transport and photovoltaic properties of c-Si solar cells were explored by considering the lengths of the ZnO NRs and the reflectance values. The 1.1 μm length of the ZnO NRs and a minimum average reflectance of 9.5% appeared to be the optimum values for ...

Journal of Materials Science: Materials in Electronics, 2021

Tremendous works have been devoted on reducing the materials costs and searching a low-cost antir... more Tremendous works have been devoted on reducing the materials costs and searching a low-cost antireflection (AR) layer in silicon (Si) solar cells. This work reports on the surface architectural of Si wafer (p-type) by growing the nanowires (NWs)-like structures through cost-effective wet-controlled etching method. The nanostructures over Si wafer were optimized in terms of sizes, lengths and densities by changing the etching conditions and thoroughly examined their growth and optoelectrical properties. The well-defined grown NWs textured on Si wafer exhibited the low average reflectance of ~ 2.25% in the full visible-NIR spectrum from 400 to 1000 nm which was well matched to the simulated average reflectance of 2.23%. A model was designed using PC1D simulation to evaluate the photovoltaic (PV) parameters of NWs textured Si wafer-based solar cells without AR layer. In this simulation, the length of SiNWs and reflectance were selected as input parameters to instigate the power conversion and quantum efficiencies of solar cells. The highest conversion efficiency of ~ 16.2% is observed when the average length of SiNWs and reflectance were ~ 2.52 μm and ~ 2.25%, respectively. Experimentally, the fabricated SiNWs-based solar cell with etching time of 20 min attained the highest conversion efficiency of 15.9% and the value was very close to simulated results. PV parameters of SiNWs-based solar cells without AR layer were comparable to commercial c-Si solar cells with SiNx AR layer. Thus, the controlled wet etching is an easy, facile method for fabrication of nanowires on Si wafer with low reflectance. The enhancement in optical and electrical properties would be expected to a great prospect in developing low-cost c-Si solar cells without AR layer.

Solar Energy, 2021

This paper describes the simulation study for the optimization of high-performance cadmium tellur... more This paper describes the simulation study for the optimization of high-performance cadmium telluride (CdTe) solar cells using different doping concentrations, carrier lifetimes, temperature, and thickness of layers of CdTe absorber and CdS window layers. In this simulation, the highest efficiencies of ~18% and ~18.29% achieved when the doping concentrations were 1.5 × 1017 cm−3 for absorber layer and 1 × 1015 cm−3 for window layer, respectively. The efficiency of the solar cell increases with increase in carrier lifetime and the highest efficiency of 18.26% achieved at carrier lifetime 100 μs with doping concentration of 1 × 1017 cm−3. Solar cell with the thickness of absorber layer 8 μm at carrier lifetime 100 μs attained the maximum efficiency of 19.18% whereas the efficiency of 18.33% was noticed in thickness of window layer 70 nm at 100 μs carrier lifetime. The optimum efficiency of 18.3% with short-circuit current 2.66 A and open-circuit voltage 0.79 V of solar cell has been achieved at operating temperature 25 °C. The optimized energy band gap of absorber (1.7 eV) accomplished the highest efficiency of 18.31%. The photogeneration rate increases logarithmically as distance from front increases, while the recombination rate increases linearly, which could be suitable for fabrication of efficient solar cell.

Molecules

This paper numerically explores the possibility of ultrathin layering and high efficiency of grap... more This paper numerically explores the possibility of ultrathin layering and high efficiency of graphene as a back surface field (BSF) based on a CdTe solar cell by Personal computer one-dimensional (PC1D) simulation. CdTe solar cells have been characterized and studied by varying the carrier lifetime, doping concentration, thickness, and bandgap of the graphene layer. With simulation results, the highest short-circuit current (Isc = 2.09 A), power conversion efficiency (η = 15%), and quantum efficiency (QE~85%) were achieved at a carrier lifetime of 1 × 103 μs and a doping concentration of 1 × 1017 cm−3 of graphene as a BSF layer-based CdTe solar cell. The thickness of the graphene BSF layer (1 μm) was proven the ultrathin, optimal, and obtainable for the fabrication of high-performance CdTe solar cells, confirming the suitability of graphene material as a BSF. This simulation confirmed that a CdTe solar cell with the proposed graphene as the BSF layer might be highly efficient with o...

Inorganics, 2022

Electrochem

Electrochem, 2022

Materials Science in Semiconductor Processing, 2022

Journal of Electronic Materials, 2022

Conference, 2019

Solar energy, 2022

Journal of Advanced Research in Dynamical and Control Systems, 2020

Engineered Science, 2021

Journal of Electronic materials, 2021

Materials Today: Proceedings, 2021

Journal of Advanced Research in Dynamical and Control Systems, 2020

Coatings, Sep 30, 2019

Applied Sciences

Journal of Materials Science: Materials in Electronics, 2021

Solar Energy, 2021

Molecules

PhD Thesis on Silicon solar cell, 2022

It is Ph.D. thesis entitled "A Study on the Surface Texturing and Antireflection Coating with Nan... more It is Ph.D. thesis entitled "A Study on the Surface Texturing and Antireflection Coating with Nanomaterials for Crystalline Silicon Solar cell" which consists of works on silicon nanowires (SiNWs), Zinc nanorods (ZnO NRs) for crystalline silicon solar cells. The SiNWs and ZnO NRs prove there is no need for an antireflection coating (ARC) layer. It also consists of works on the impact of single and double antireflection coating layers of ZnO, Ag-ZnO, and Graphene Oxide (GO) for enhancement of optoelectrical properties of crystalline silicon solar cells.

Master Project work, 2002

It is the project work of a Master of Science in Renewable Energy Engineering (MSREE) entitled “S... more It is the project work of a Master of Science in Renewable Energy Engineering (MSREE) entitled “Study on Implementation of Solar Photovoltaic Traffic Lighting System for Gwarko, Lalitpur, Nepal” in 2004. In this work, a comparison of power consumption of energy and economic analysis has been accomplished between solar-powered and grid-connected traffic lighting systems with multicolor LED lamps. Additionally, a comparison of power consumption of energy and economic analysis has been accomplished between different types of solar cells. The power consumption for the traffic control system is 23.69 times less (i.e. 95.78 % efficient) by using a multi-color LEDs lamp instead of the traditional incandescent lamp in the traffic lighting system. The life of an LED lamp is 33.34 times more (i.e. 97 % efficient) than a traditional incandescent lamp. The incandescent lamp is replaced about 40 times whereas the LED lamp is replaced only one time during operation of 20 years in the traffic lighting system. The payback period of the system using the LED lamp and solar energy having monocrystalline solar cell is 3.46 years and the system using the LED lamp and power supply by National grid is 2.11 years when compared with incandescent lamp.