Synthesis of in-gap band CuGaS2:Cr absorbers and numerical assessment of their performance in solar cells

Abstract

CuGaS2 thin films were obtained by sulfurization of CuGaSe2. CuGaSe2 thin films were first electrodeposited from aqueous solutions containing CuCl2, GaCl3, and H2SeO3 and subsequently annealed at 400 °C for 10 min in forming gas atmosphere and in the presence of molecular sulfur. This sulfurization process resulted in the complete conversion of CuGaSe2 into CuGaS2. The formation of CuGaS2 was proven by X-Ray diffraction and optical spectroscopy. Diffraction peaks of CuGaS2 shifted to higher angles than those observed for CuGaSe2 films, and the optical band gap shifted to blue rising from 1.66 eV for CuGaSe2 to 2.2 eV for CuGaS2. When Cr ions were added to the initial electrolyte, the final CuGaS2 films exhibited a broad in-gap absorption band centred at 1.63 eV that can be ascribed to Cr atoms in Ga sites. The performance of solar cells based on CuGaS2:Cr absorbers containing an in-gap absorption band was then estimated by numerical simulation using Solar Cell Capacitance Simulator Software. Both quantum efficiency and short circuit current of simulated Mo/CuGaS2:Cr/CdS/ZnO solar cells rose up proportionally to the amount of Cr present in CuGaS2:Cr absorbers. As a result, the photo conversion efficiency of the simulated devices changed from 14.7% for CuGaS2 to 34% for CuGaS2:Cr absorbers. Nevertheless, when neutral defects related to Cr-doping were introduced in the absorber layer, the positive effect of the enhancement of photon harvesting due to IGB was compensated by a decline in the carrier collection and the overall efficiency of the device fell considerably.

Synthesis and Characterization of N-Type CuGaS2 Nanoparticles and Films for Purpose of Photoelectrocatalytic Water Splitting

“…36,37 and literature results for this material. [37][38][39] The average crystallite size (D) of the annealed CuGaS 2 powder sample was estimated from Debye-Scherrer's Eq. 6 using the full width at half maximum (FWHM) of the more intense reflection line (112) expressed in radians (β): 40…”

First-principles insight on the electronic and optical properties of Ge-based inorganic perovskites

“…35) These materials have been synthesized experimentally. [36][37][38][39] Therefore, these results indicate that Rb-doped CsGeI 3 perovskites should be synthesized by using the suitable synthesis method.…”

Double‐Pulse Electrodeposition of CuGaS2 Photovoltaic Thin Film

“…It has been considered a promising material due to its wide band gap energy (∼2.4–2.5 eV) and high absorption coefficient for high efficiency tandem solar cell, intermediate band solar cells, and green light emitting diodes. Its bandgap is close to the optimum for the fabrication of intermediate band thin film solar cells, theoretically able to reach value of energy conversion efficiency of ∼63 %, significantly higher than the theoretical value for a single band‐gap solar cell (∼41 %) . CGS films has been deposited by several reported approaches: vacuum‐based techniques, spray pyrolysis, nanocrystalline ink‐based deposition, electrodeposition, etc.…”

“…Its bandgap is close to the optimum for the fabrication of intermediate band thin film solar cells, [3] theoretically able to reach value of energy conversion efficiency of 63 %, significantly higher than the theoretical value for a single band-gap solar cell (~41 %). [4] CGS films has been deposited by several reported approaches: vacuum-based techniques, [5,6] spray pyrolysis, [7] nanocrystalline ink-based deposition, [8,9] electrodeposition, [10] etc. Among these mentioned deposition techniques, electrodeposition offers low-cost equipment, efficient material utilization and scalability for large scale production.…”