Stability-oriented design of a MoO3/TAPC hybrid bilayer hole transport layer for scalable organic solar cells

Abstract

Organic solar cells (OSCs), recognized for their scalability, light weight, mechanical flexibility, and solution processability, increasingly employ interfacial engineering strategies to boost device performance, enhance scalability, and lower overall costs. Herein, we introduce a hybrid bilayer hole transport layer (HTL) strategy that integrates TAPC (4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine]) with MoO₃ to simultaneously address the stability limitations of conventional MoO₃ and enhance the scalability of inverted OSCs. The spin-coated TAPC interlayer beneath a thermally evaporated MoO₃ layer suppresses interfacial recombination and facilitates charge transport through its well-aligned energy levels and optimized surface morphology. The hybrid HTL, consisting of a 2.5 nm MoO₃ layer on 0.5 mg mL⁻¹ TAPC, delivers reliable long-term operational photostability while retaining device efficiency, achieving a power conversion efficiency (PCE) of 16.49% in unit cells without compromising device performance compared to the single-layer MoO₃ device. Furthermore, when scaled up to a mini-module (4.725 cm²), the same device architecture achieved a PCE of 13.95%. These results demonstrate the potential of MoO₃/TAPC hybrid HTLs as a scalable and stable architecture, enabled by their favorable electrical properties and efficient interface engineering.