Enhancing Efficiency of Large-Area Wide-Bandgap Perovskite Solar Modules with Spontaneously Formed Self-Assembled Monolayer Interfaces

Abstract

Wide-bandgap (WBG) perovskites play a crucial role in perovskitebased tandem cells. Despite recent advances using self-assembled monolayers (SAMs) to facilitate efficiency breakthroughs, achieving precise control over the deposition of such ultrathin layers remains a significant challenge for large-scale fabrication of WBG perovskite and, consequently, for the tandem modules. To address these challenges, we propose a facile method that integrates MeO-2PACz and Me-4PACz in optimal proportions (Mixed SAMs) into the perovskite precursor solution, enabling the simultaneous codeposition of WBG perovskite and SAMs. This technique promotes the spontaneous formation of charge-selective contacts while reducing defect densities by coordinating phosphonic acid groups with the unbonded Pb 2+ ions at the bottom interface. The resulting WBG perovskite solar cells (PSCs) demonstrated a power conversion efficiency of 19.31% for small-area devices (0.0585 cm 2 ) and 17.63% for large-area modules (19.34 cm 2 ), highlighting the potential of this codeposition strategy for fabricating high-performance, large-area WBG PSCs with enhanced reproducibility. These findings offer valuable insights for advancing WBG PSCs and the scalable fabrication of modules. P erovskite solar cells (PSCs) have undergone rapid advancement, thanks to their unique properties such as tunable bandgap, high absorption coefficient, long carrier diffusion length, low exciton binding energy, and more. 1−4 Over the past decade, the power conversion efficiency (PCE) of PSCs has surged from 3.8% to 26.1%. 5−7 As single-junction PSCs approach their efficiency limit, researchers increasingly focus on perovskite-based tandem cells, such as perovskiteperovskite, 8 perovskite-silicon, 9 perovskite-organic, 10 and perovskite-CIGS 11 configurations. The wide-bandgap (WBG) perovskite subcell is a common component in these tandems and crucial for determining tandem device efficiency. Recently, researchers widely employed self-assembled monolayers (SAMs) as hole transporting layers (HTLs) in middle-bandgap (MBG) PSCs like FAPbI 3 , leading to rapid efficiency breakthroughs. 12,13 This strategy may extend to WBG perovskites as well, with successful demonstrations of SAMs enhancing WBG PSCs' efficiency. 14−17 However, precise control of SAMs deposition remains a significant challenge for fabricating large-scale WBG perovskites and ultimate tandem modules. Inspired by recent studies on doping SAM molecules into MBG perovskite precursors, 18−20 we propose a facile processing method to simultaneously deposit WBG perovskite and SAMs for large area modules.