Defect Passivation of Buried Perovskite Interface for Top‐Illuminated Thin‐Film Imager

Abstract Minimizing reverse‐bias dark current density ( J d ) while retaining high photoresponse is vital for top‐illuminated perovskite photodiodes. It remains challenging to thoroughly clarify the inherent origin of J d . In this work, the buried interface is demonstrated to play a critical role in J d for top‐illuminated perovskite photodiodes. Introducing an Al 2 O 3 thin layer at the NiO x /perovskite interface turns out to be a simple and effective approach to suppressing J d . Such interfacial modification has dual positive effects. One is to facilitate the favorable morphology of perovskites with compact grain boundaries, thus impeding the leakage current through shunt resistance. The other is to reduce the interfacial trap states, thereby decreasing the trap‐assisted tunneling current. The resulted top‐illuminated perovskite photodiodes exhibit outstanding photodetection performances, including an ultralow J d of 8 × 10 −10 A cm −2 at −0.1 V, a remarkable specific detectivity of 1.5 × 10 12 Jones, and a fast response time of only 410 ns. Leveraging these device merits, the perovskite photodiodes are monolithically integrated onto a thin‐film transistor array to obtain the 64 × 64 top‐illuminated imager. The perovskite imager is utilized to implement an intelligent vision system with the ability of basic visual perception, which highlights the tremendous potential of the top‐illuminated perovskite photodiodes in versatile imaging applications.