Brijesh Tripathi

Effect of temperature and concentration on commercial silicon module based low-concentration photovoltaic system

A low-concentration photovoltaic (LCPV) system has immense potential for further cost reduction of solar photovoltaic (PV) power as compared to flat panel PV. This paper explains the performance of commercially available solar PV module mounted on parabolic trough collector experimentally and theoretically. A piecewise linear parabolic trough collector is modeled and designed to focus the solar radiation with uniform intensity on solar PV module. Silicon solar PV module based LCPV system is also modeled and simulated to study the variation of output power, open-circuit voltage, and short-circuit current with respect to module temperature and irradiance. The developed theoretical model is able to predict the performance of a LCPV system under the actual test conditions (ATCs). It was observed that the open-circuit voltage decreases from 9.86 to 8.24 V with temperature coefficient of voltage ≈−0.021 V/K under ATC. The short-circuit current of LCPV system shows increasing trend with light concentration with ...

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) 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  to 90.34  with the increase in illumination level from 200 W/m2 to 800 W/m2. 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.

High-performance self-powered perovskite photodetector with a rapid photoconductive response

Here we report the development of a self-powered high-speed perovskite Schottky junction photodiode, which is very important for next-generation electronic devices. The ITO/perovskite Schottky junction diode yielded a rectification behaviour with a low value of reverse saturation current under dark conditions, and a zero bias photocurrent when illuminated. The fabricated photodiode exhibited a high photosensitivity with fast response and recovery times. The origin of the high photocurrent in the fabricated photodiode was analysed by making a log–linear plot of its current–voltage characteristics. The study also demonstrated the efficient charge transport properties of the CH3NH3Pbl3 semiconductor material with the photogenerated electrons injected into the ITO contact and the holes injected into the gold contact. The obtained results provide a way to fabricate an efficient self-bias photodiode for future electronic devices.

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

In the present study, a novel solution-processable 1,6,7,10-tetramethylfluoranthene (1), as the smallest fragment of fullerene, is synthesized and systematically studied for use as a non-fullerene acceptor in an organic solar cell (OSC). Molecule 1 has the potential to be synthesized on a large scale. Optical and electrochemical studies revealed that 1 has a high absorption range and an appropriate band gap, which is compatible with poly(3-hexylthiophene-2,5-diyl) (P3HT) as a donor. The morphology showed high intermixed blend with uniform distribution of donor–acceptor molecules. Steady state and time resolved photoluminescence studies showed efficient charge separation from the donor and acceptor. These studies can be confirmed by the conventional OSC device structure employing a blend of P3HT:1, which gives a power conversion efficiency (PCE) of up to 0.71% with an open circuit voltage (VOC) of 0.52 V and a fill factor (FF) of 44.89%. Despite this, the significant stability of the device, even after 60 h in open air, demonstrates that this molecule shows promising output and the result can be enhanced in the future with further optimization.

Exergy, Energy, and Dynamic Parameter Analysis of Indigenously Developed Low-Concentration Photovoltaic System

Piecewise linear parabolic trough collector (PLPTC) is designed and developed to concentrate solar radiation on monocrystalline silicon based photovoltaic module. A theoretical model is used to perform electrical energy and exergy analysis of low-concentration photovoltaic (LCPV) system working under actual test conditions (ATC). The exergy efficiency of LCPV system is in the range from 5.1% to 4.82% with increasing rate of input exergy rate from 30.81 W to 96.12 W, when concentration ratio changes from 1.85 to 5.17 Sun. Short-circuit current shows increasing trend with increasing input exergy rate of ≈0.011 A/W. Power conversion efficiency decreases from 7.07 to 5.66%, and open-circuit voltage decreases from 9.86 to 8.24 V with temperature coefficient of voltage V/K under ATC. The results confirm that the commercially available silicon solar PV module performs satisfactorily under low concentration.

Influence of optical properties of ZnO thin-films deposited by spray pyrolysis and RF magnetron sputtering on the output performance of silicon solar cell

ZnO thin-films were deposited by spray pyrolysis and RF magnetron sputtering techniques. The optical reflection of these thin-films is measured using UV-Vis spectrophotometer. The measured optical reflection data is used in PC-1D simulation software to study the output performance of commercial silicon wafer-based solar cell. As far as optical performance is concerned it could be demonstrated that the sprayed ZnO thin-film under laboratory conditions show equivalent performance compared to sputtered ZnO thin-film. The influence of optical properties of 65 nm thick zinc oxide thin-films deposited by vacuum and non-vacuum techniques on quantum efficiency and IV characteristics of commercial silicon-wafer based solar cell is studied and reported here.

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

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 in Sn-doped α-Fe2O3 nanostructure. The Sn-doped α-Fe2O3 nanostructure exhibit a photocurrent density of 1.2 mA/cm2 at 1.4 V versus RHE electrode.

A study of the applicability of ZnO thin-films as anti-reflection coating on Cu2ZnSnS4 thin-films solar cell

Transparent ZnO thin-films are prepared using the RF magnetron sputtering and spray pyrolysis techniques on the glass substrates. Reflectance spectra and thin films heights are measured using spectrophotometer and stylus surface profiler, respectively. Measured optical data is used for investigating the effect of the ZnO prepared by above two processes on the performance of Cu2ZnSnS4 (CZTS) thin films solar cell (TFSC). One dimensional simulation approach is considered using the simulation program, SCAPS. External quantum efficiency and J-V characteristics of CZTS TFSC is simulated on the basis of optical reflectance data of ZnO films with and without ZnO thin-films as antireflection coating (ARC). Study shows that ARC coated CZTS TFSC provides a better fill factor (FF) as compared to other ARC material such as MgF2. Sprayed ZnO thin-films as ARC show comparable performance with the sputtered samples.

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

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 () 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 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 degraded DSC. It is also confirmed from EIS that the degradation leads to a better contact formation between the electrolyte and Pt electrode, which improves the fill factor of the DSC. But the recombination throughout the DSC is found to increase along with degradation. This study suggests that the DSC should be used under low illumination conditions and around room temperature for a longer life.