Ferrocene Derivatives Enable Ultrasensitive Perovskite Photodetectors with Enhanced Reverse Bias Stability

Abstract

Despite the great potential of lead-halide perovskite photodetectors for broadband photodetection, ion migration in perovskites and parasitic charge injection from adjacent layers remain major challenges, ultimately leading to device failure. Here, the novel use of an ultra-thin layer of ferrocenyl-bis-phenyl-2-carboxylate (FcPhc₂) is demonstrated as a hole-blocking layer. It is shown that FcPhc₂ creates an energetic barrier between the perovskite and the electron transport layer, significantly reducing hole injection from the Ag contact. This improvement results in an ultralow noise spectral density of 1.2 × 10⁻¹⁴ A Hz^−1/2, and a high specific detectivity of 8.1 × 10¹² Jones at −0.5 V and 740 nm. In addition, FcPhc₂ effectively inhibits I⁻ oxidation induced by injected holes and reduces formed I₂ on the perovskite surface, enhancing reverse bias stability. The increase in detectivity and stability does not compromise the high response speed of FcPhc₂-based devices that operate on the scale of 150 ns and 1.3 MHz at −0.5 V in photo- and electrical-responses.