Molecular-templated pre-assembly of self-assembled monolayer for perovskite solar cells and modules with improved reverse-bias stability

Abstract

Perovskite solar modules, particularly those using ultrathin self-assembled monolayer (SAM)-based hole transport layers, suffer from reverse-bias instability. Here we identified that discontinuous SAM distribution causes shunting and a lower breakdown voltage, while indium tin oxide-triggered electrochemical deprotonation of formamidinium ions leads to reduced long-term stability under reverse-bias conditions. To address these issues, we developed a molecular-templated pre-assembly strategy driven by hydrogen-bonding interactions between the SAM and a polycarbazole template. This approach ensures homogeneous clusters in solution and strong substrate interactions, yielding dense and uniform layers. Subsequently, we prepared minimodules with 24.0% efficiency (certified steady-state efficiency of 23.2%) and improved reverse-bias stability. Small-area devices retained 95% efficiency after 300 h at −4.8 V, while minimodules exhibited a T98 lifetime of 312 h under negative open-circuit voltage stress. We showed that a single bypass diode can protect at least 16 subcells, setting a new reliability benchmark for scalable perovskite photovoltaics. Perovskite solar modules suffer from reverse-bias instability. To address this, Wang et al. promote the assembly of self-assembled monolayers through hydrogen-bonding interactions with a polycarbazole template.