Enhancing operational stability and radiation hardness of p-i-n perovskite solar cells via a hybrid polymer-based self-assembled hole-transport layer

Abstract

The instability of the buried perovskite interface, driven by the diffusion of self-assembled molecular hole-transport materials (SAM HTMs), presents a major obstacle for p-i-n perovskite photovoltaics. Herein, we introduce a stabilizing strategy using PTA‑COOH, a poly(triarylamine) polymer functionalized with carboxylic acid anchors, as one of the first polymeric SAM HTMs. By blending PTA‑COOH with the small molecule Me‑4PACz, we create a hybrid HTM that synergistically combines the benefits of polymeric and molecular SAMs. This approach provides superior control over film morphology, NiOx substrate coverage, and interfacial energy level alignment. Crucially, the PTA‑COOH matrix effectively suppresses the diffusion of Me‑4PACz into the perovskite layer, dramatically stabilizing the critical perovskite/HTL interface. As a result, perovskite solar cells (PSCs) fabricated with the Me‑4PACz+PTA‑COOH composite HTL achieve significantly enhanced operational stability and radiation hardness—critical metrics for both terrestrial and space applications. This study establishes hybrid polymeric SAMs as a transformative strategy for HTL engineering, paving the way for the stability enhancement of p-i-n perovskite photovoltaics.