Towards high-performance photodiodes based on p-Si/perovskite heterojunction

Abstract

Photodiodes based on Si/perovskite heterojunction have been intensively studied due to their broad spectral photodetection. However, device optimization of the perovskite layer thickness and the top electrode is rarely tackled. In this work, we first investigated the effect of perovskite thickness on the performance of photodiodes with the structure of “Si/perovskite/Ag (comb-shaped)”. The photodiode with 170 nm perovskite layer shows the highest responsivity (R) for lights with wavelengths between 532 nm and 650 nm, while the photodiodes with 539 nm perovskite layer has the highest R in the 808–850 nm range. The specific detectivity (D*) exhibits maximal values for all wavelengths at perovskite layer thickness of 170 nm. Furthermore, by introducing copper phthalocyanine (CuPc) as the buffer layer, we successfully utilized Al as the top electrode in photodiodes based on Si/perovskite heterojunction with improved device performance. The CuPc-thickness dependent performance was investigated, and an optimal thickness of ∼ 10 nm was determined, achieving a high photo responsivity of 1.77 A/W and D* of 6.8 × 1011 Jones, which are around 3 and 7 times higher than those of the Ag-based device, respectively.