Employing PEDOT:PSS as a Hole Transport Material in Regular Rudorffite AgBiI₄ Solar Cells for Indoor Photovoltaics

The recent surge in interest for Pb-based perovskites in indoor photovoltaics (IPVs) is tempered by concerns over the toxic nature of Pb. The wide bandgap rudorffite AgxBiyIx+3y (ABI) emerges as a promising Pb-free alternative for IPV absorbers. The conventional choice for a hole transport material (HTM) in ABI devices, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), is employed without additives due to ABI’s susceptibility to corrosion. This work introduces, for the first time, a regular n–i–p ABI solar cell incorporating poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the HTM, utilizing water-free PEDOT:PSS dispersions. We analyzed the photovoltaic performance of these devices under AM 1.5G 1 sun and 1000 lx white light-emitting diode illumination. Owing to PEDOT:PSS’s superior conductivity and the reduced recombination at the PEDOT:PSS/AgBiI4 interface, the PEDOT:PSS-based devices exhibited a significant enhancement in power conversion efficiency under 1000 lx compared to their PTAA-based counterparts, achieving a stabilized output of 3.3% (10.8 μW/cm2) for the optimal device. The stability of PEDOT:PSS-based devices was assessed in an ambient atmosphere without encapsulation. Although exhibiting exceptional stability under 1 sun, the devices retained only 67.7% of their initial PCE after 33 days under 1000 lx, revealing a heightened sensitivity to aging under low-light conditions.