Structural and photoelectrochemical evaluation of nanotextured Sn-doped AgInS₂ films prepared by spray pyrolysis

Spray pyrolysis was used to prepare films of AgInS₂ (AIS) with and without Sn as an extrinsic dopant. The photoelectrochemical performance of these films was evaluated after annealing under a N₂ or S atmosphere with different amounts of the Sn dopant. DFT was used to calculate the band structure of AIS and understand the role of Sn doping in the observed properties. All AIS films were n-type, and Sn was found to increase the photocurrent and carrier concentration of AIS with an optimum doping level of x=[Sn]/([Ag]+[In])=0.02, which gave a photocurrent of 4.85 mA cm^-2. Above this level, the Sn dopants were detrimental to the photoelectrochemical performance, likely a result of a self-compensating effect and the introduction of a deep acceptor level, which could act as a recombination site for photogenerated carriers. Tin best or tin pest? The role of Sn extrinsic dopants in chalcopyrite AgInS₂ is investigated to understand their effects on the optical, electronic, and photoelectrochemical properties of this promising photoanode material. We found that at low amounts, Sn increased the AgInS ₂ carrier concentration and photocurrent, but was detrimental at higher dopant concentrations.