A P3HT-stabilised Spiro-OMeTAD composite hole transport material for high-performance perovskite optoelectronic devices

The advancement of perovskite optoelectronics is closely tied to the development of robust charge-transport layers. While Spiro-OMeTAD remains the benchmark hole-transport material (HTM), its practical application is limited by stability issues inherent to chemical doping. This work explores a composite approach to enhance Spiro-OMeTAD in triple-cation perovskite solar cells (TC-PSCs) by incorporating a low concentration of P3HT as a stabilising agent. The optimal composition ( S p i r o O M e T A D 0 . 9 4 : P ⁢ 3 ⁢ H T 0 . 0 6 , P6) synergistically combines favourable energetics with the hydrophobic nature and morphological compatibility of P3HT, leading to improved interfacial coverage and stability. In PSCs, the P6 composite achieves a PCE of 20.7%, outperforming pristine Spiro-OMeTAD through enhanced hole extraction and reduced carrier lifetimes. Supporting analyses, including SCLC, EIS, and EQE, confirm improved mobility, charge transport, and photocurrent generation, while MPPT validates stable operational output. The composite strategy also extends to photodetectors, where self-powered devices exhibit responsivity gains of 46% (532 nm) and 24% (655 nm), with detectivities up to 3.8 × 10 12 Jones. Moreover, the P6 composite confers exceptional moisture resistance, suppressing δ-phase evolution under 80% ± 5% RH and enabling unencapsulated devices to retain over 80% of their initial efficiency for 920 h. This composite HTM architecture offers a scalable pathway to stable, high-performance perovskite optoelectronics.