Extrinsic dopants in quasi-one-dimensional photovoltaic semiconductor Sb₂S₃: A first-principles study Available to Purchase

Extrinsic elements such as C, Zn, Sn, Bi, and Ti had been doped into Sb₂S₃ in order to increase the electrical conductivity and thus the photovoltaic efficiency. However, the influences of these dopants are so far unclear. Using the first-principles calculations, we show that (i) Zn and Sn doping can slightly increase the p-type conductivity of Sb₂S₃ through forming Zn_Sb2 and Sn_Sb2 acceptors, explaining the observed increase in photocurrent and carrier concentration; (ii) in contrast, the formation energies of C dopants on different sites are high, which means C doping cannot increase the conductivity of Sb₂S₃ obviously, so the highly reduced resistivity of C-doped Sb₂S₃ in experiments cannot be explained and the effects of C doping should be revisited; (iii) Bi_i acts as the carrier recombination center, so the photocurrent of the Bi-doped Sb₂S₃ solar cells decreases; and (iv) the formation energies (concentration) of Ti_i and Ti_Sb1 donors are extremely low (high), so the photocurrent of the Ti doped Sb₂S₃ solar cells increases significantly. Considering the influences on both electrical conductivity and carrier non-radiative recombination, we propose that Pb and Cl are relatively benign p-type and n-type dopants, respectively. Cl doping can make Sb₂S₃ show high n-type conductivity and long minority carrier lifetime, thus offering a promising method for overcoming the current efficiency bottleneck of Sb₂S₃ solar cells.