Ambient-processed semitransparent perovskite solar cells from eco-friendly solvents

The development of semitransparent perovskite solar cells is crucial for applications in building-integrated photovoltaics, agrivoltaics, and tandem solar cells. However, optimizing their efficiency while maintaining high transparency and employing eco-friendly solvents remains challenging. In this work, we investigate the impact of solvent engineering and processing conditions on the structural, optical, and photovoltaic properties of perovskite thin films. First, we demonstrate that dimethyl sulfoxide (DMSO), an eco-friendly solvent, can be used as a standalone alternative to the widely used and hazardous N,N-dimethylformamide:DMSO co-solvent system for ambient-processed FA_0.77MA_0.23PbI_2.74Cl_0.26perovskite. We also assess the effects of antisolvent treatments (IPA and EtOH) on crystallinity, charge carrier dynamics, and device performance. Additionally, we show that reducing the gold electrode thickness from 80 nm to 30 nm significantly enhances device-level transparency, as confirmed through full-stack optical measurements. We achieve a power conversion efficiency of up to 10.9% and demonstrate semitransparency, with a light utilization efficiency (LUE) exceeding 4.26% in 30 nm gold top electrode DMSO-only devices, using solely thin-film transmittance. Using the full device stack, the semitransparent devices yield a LUE of 0.59%, highlighting the inadequacy of relying solely on thin-film transmittance. Notably, DMSO-based devices exhibit superior semitransparency and sustainability despite lower efficiencies. Our findings highlight a viable pathway to scalable, eco-friendly, ambient-processed semitransparent perovskite solar cells that balance efficiency, transparency, and environmental considerations for future energy applications.