Tunable and Low‐Acidity PEDOT:SAM Supramolecular Complex Hole‐Transport Materials for High‐Performance All‐Perovskite Tandem Solar Cells

The development of advanced hole-transport materials (HTMs) is critical for next-generation optoelectronics. While poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) is one of the most widely used HTMs, its inherent acidity and poor interfacial stability represent a universal challenge across diverse devices. This issue becomes particularly acute in all-perovskite tandem solar cells (APTSCs), where the instability of the narrow-bandgap (NBG) subcell, exacerbated by PEDOT:PSS, severely limits their operational lifetime. Here, we present a tunable and low-acidity supramolecular complex HTM, PEDOT:SAM, synthesized via a one-step oxidative polymerization that integrates EDOT with a carbazole-phosphonic acid-based molecular monomer. This design creates an adaptive, stress-relieving interface and a chemically benign environment, effectively suppressing perovskite degradation. Consequently, NBG perovskite solar cells with PEDOT:SAM achieve a power conversion efficiency (PCE) of 23.7%. When integrated into APTSCs, a champion PCE of 28.76% (certified 27.99%) is attained. The tandem devices retain over 80% of their initial PCE after over 1000 h of maximum power point tracking under 1-sun illumination, starkly outperforming the PEDOT:PSS-based devices. This work provides a generalizable materials platform to overcome key stability challenges in perovskite photovoltaics and beyond.