Antimony-Bismuth Alloying: The Key to a Major Boost in the Efficiency of Lead-Free Perovskite-Inspired Photovoltaics

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 19; no. 46; p. e2303575
• Main Authors: Al-Anesi, Basheer, Grandhi, G Krishnamurthy, Pecoraro, Adriana, Sugathan, Vipinraj, Viswanath, Noolu Srinivasa Manikanta, Ali-Löytty, Harri, Liu, Maning, Ruoko, Tero-Petri, Lahtonen, Kimmo, Manna, Debjit, Toikkonen, Sami, Muñoz-García, Ana Belén, Pavone, Michele, Vivo, Paola
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.11.2023
• Subjects: Absorbers; Absorptivity; Alloying; Antimony; Bismuth; Circuit design; Crystal defects; Design defects; Energy conversion efficiency; Energy gap; Free energy; Heat of formation; Lattice sites; Luminous intensity; Nanotechnology; Perovskites; Photovoltaic cells; Solar cells; Surface defects; perovskite-inspired material; wide-bandgap; low-toxicity; photovoltaics; defects
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202303575

The perovskite-inspired Cu AgBiI (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 10  cm . 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) (Sb ) is introduced into the octahedral lattice sites of the CABI structure, leading to CABI-Sb with larger crystalline domains than CABI. The alloying of Sb with bismuth (III) (Bi ) 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.