A comprehensive review on synthesis and characterizations of Cu3BiS3 thin films for solar photovoltaics

Abstract

Since the last few decades, light-absorbing materials based on CuInGaSe 2 (CIGS), CuInS 2 (CIS), and CdTe have dominated the research in thin-film solar cells.To fabricate large-scale solar cells from these materials, problems may arise due to limited availability of the constituents, viz. Se, In, Cd, and Te, and the toxicity of some of these elements. Hence, recent research efforts are attentive toward abundantly available non-toxic, larger value of absorption coefficient and non-conventional elements. The Cu 3 BiS 3 having wittichenite orthorhombic structure is one the most promising absorber layer candidates for low-cost thin-film solar cells. It has suitable direct band gap (1.10-1.86 eV), large absorption coefficient (10 5 cm -1 ) with composition of earth abundant, and relatively non-toxic and cost-effective constituents. Till now, a majority work was done on the preparation of Cu 3 BiS 3 thin films by various techniques. Therefore, a comprehensive review of recent literature of Cu 3 BiS 3 is urgently required. This paper will review the various techniques that have been used to deposit Cu 3 BiS 3 semiconductor with the hope of new paths for the beginner.

Solution Processing Cu3BiS3 Absorber Layers with a Thiol–Amine Solvent Mixture

“…The experimental band gap of the Cu 3 BiS 3 thin films was determined to be 1.47 eV. This optical band gap lies well within the previously reported experimentally reported band gaps for Cu 3 BiS 3 (1.10–1.80 eV) …”

“…The reciprocal of the line of best fit from the linear regression of the ILD plot gives the exponential factor ( m ), which informs the type of electronic transition. Wittichenite Cu 3 BiS 3 has been calculated and experimentally confirmed to be a direct band-gap semiconductor . From this one would expect an exponential factor m of 0.5 (slope of 2) for a direct band-gap semiconductor.…”

“…Wittichenite Cu 3 BiS 3 has been calculated and experimentally confirmed to be a direct band-gap semiconductor. 30 From this one would expect an exponential factor m of 0.5 (slope of 2) for a direct band-gap semiconductor. Importantly, Jarosinḱsi et al shows that for direct band-gap thin film samples of TiO 2 and MoS 2 , the exponential factor yielded values of 1 because of the polycrystalline nature of the sputtered films, which affects the effective dimension and dispersion relations of the thin films.…”

“…This optical band gap lies well within the previously reported experimentally reported band gaps for Cu 3 BiS 3 (1.10−1.80 eV). 30 The reciprocal of the line of best fit from the linear regression of the ILD plot gives the exponential factor (m), which informs the type of electronic transition. Wittichenite Cu 3 BiS 3 has been calculated and experimentally confirmed to be a direct band-gap semiconductor.…”

“…Thin films of wittichenite Cu 3 BiS 3 have been deposited by physical vapor deposition methods, including sputtering , and thermal evaporation, , but these methods are generally much more energy intensive and costly than solution processing . While Cu 3 BiS 3 thin films have been solution deposited with nonvacuum-based techniques, such as spray pyrolysis, , electrodeposition, , and chemical bath deposition, , solution deposition of Cu 3 BiS 3 thin films is still challenged by the need for presynthesized, noncommercially available precursors, extra postdeposition sulfurization steps, − amorphous films, low absorption coefficients (<10 5 cm –1 ), and/or films with high band gaps (>1.6 eV). , To overcome some of the general issues with solution processing of chalcogenides, our group reported a binary solvent mixture (termed an “alkahest”) comprised of thiols and amines that dissolves in excess of 100 different bulk materials, including metals, metal oxides, and metal chalcogenides, to form solution-processable semiconductor inks. − A simple dissolve and recover approach can be used to produce chalcogenide thin films through solution deposition and mild annealing. In the absence of an external chalcogen source, the thiol acts as a competent sulfur source to produce polycrystalline metal sulfides.…”