{Reference Type}: Journal Article
{Title}: Antimony-Bismuth Alloying: The Key to a Major Boost in the Efficiency of Lead-Free Perovskite-Inspired Photovoltaics.
{Author}: Al-Anesi B;Grandhi GK;Pecoraro A;Sugathan V;Viswanath NSM;Ali-Löytty H;Liu M;Ruoko TP;Lahtonen K;Manna D;Toikkonen S;Muñoz-García AB;Pavone M;Vivo P;
{Journal}: Small
{Volume}: 19
{Issue}: 46
{Year}: 2023 Nov 14
{Factor}: 15.153
{DOI}: 10.1002/smll.202303575
{Abstract}: The perovskite-inspired Cu2 AgBiI6 (CABI) material has been gaining increasing momentum as photovoltaic (PV) absorber due to its low toxicity, intrinsic air stability, direct bandgap, and a high absorption coefficient in the range of 105  cm-1 . However, the power conversion efficiency (PCE) of existing CABI-based PVs is still seriously constrained by the presence of both intrinsic and surface defects. Herein, antimony (III) (Sb3+ ) is introduced into the octahedral lattice sites of the CABI structure, leading to CABI-Sb with larger crystalline domains than CABI. The alloying of Sb3+ with bismuth (III) (Bi3+ ) induces changes in the local structural symmetry that dramatically increase the formation energy of intrinsic defects. Light-intensity dependence and electron impedance spectroscopic studies show reduced trap-assisted recombination in the CABI-Sb PV devices. CABI-Sb solar cells feature a nearly 40% PCE enhancement (from 1.31% to 1.82%) with respect to the CABI devices mainly due to improvement in short-circuit current density. This work will promote future compositional design studies to enhance the intrinsic defect tolerance of next-generation wide-bandgap absorbers for high-performance and stable PVs.