High-efficiency perovskite photodetectors using manganese dioxide oxidation Spiro-OMeTAD as hole transport layer

Spiro-OMeTAD is a commonly used hole transport layer (HTL) in perovskite photodetectors (PDs) due to its high glass transition temperature, good solubility in organic solvents, amorphous nature, and better energy level alignment with perovskite layers, etc. However, the unoxidized Spiro-OMeTAD has low electrical conductivity and hole mobility, while air oxidation raises device performance and reproducibility issues. In this study, we successfully achieved early and rapid oxidation of Spiro-OMeTAD by introducing a quantitative amount of manganese dioxide (MnO2), circumventing the challenges of air oxidation and greatly reducing device preparation time and cost. Additionally, MnO2-doped HTLs exhibited significantly improved PD performance, with specific detectivity (D*) increased from 4.36 × 1012 Jones to 4.14 × 1013 Jones. Unpackaged MnO2-doped PDs maintained about 81.4 % of the initial EQE value in the glove box after one month, showing remarkable stability. This work demonstrates the feasibility of using MnO2 as an oxidizing agent for Spiro-OMeTAD and allows us to appreciate the potential of transition metal-based oxides in the oxidation of HTMs.