Spiro-type Self-assembled Hole Transporting Monolayer for Highly Efficient and Stable Inverted Perovskite Solar Cells and Modules

Abstract

Self-assembled monolayers (SAMs) have significantly contributed to the advancement of hole-transporting materials (HTMs) for inverted perovskite solar cells (PSCs). However, the non-uniform distribution of SAMs on the substrate largely decreases the PSC performance, especially for large-scale devices. Herein, the first spiro-type SAM, termed 4PA-Spiro, with an orthogonal spiro[acridine-9,9'-fluorene] as the skeleton and the phosphonic acid as the anchoring group, were proposed. Compared to the reference 4PACz, the twisted configuration with the larger steric hindrance of 4PA-Spiro inhabiting the intermolecular aggregation, enabling a uniform and homogeneous anchoring on the substrate. Moreover, the suitable highest occupied molecular orbitals (HOMO) level of 4PA-Spiro is beneficial in promoting holes extraction and reducing charge non-radiative recombination. As a result, compared to the 4PACz with power conversion efficiency (PCE) of 22.10%, the 4PA-Spiro-based PSCs exhibited a superior PCE of 25.28% (certified 24.81%, 0.05 cm2), along with excellent long-term stability. More importantly, 4PA-spiro enabled lager-area PSCs and modules achieved PCEs of 24.11% (1.0 cm2) and 21.89% (29.0 cm2), respectively, one of the highest PCEs for inverted PSC modules, providing an effective SAM candidate for the commercialization of efficient, stable and large-scale inverted PSCs.