High-performance p–i–n perovskite photodetectors and image sensors with long-term operational stability enabled by a corrosion-resistant titanium nitride back electrode

Despite the impressive developments in perovskite optoelectronic devices, their long-term stability remains a major challenge. Chemical reactions and ion exchange at the metal/perovskite contact interface are two significant factors that lead to the failure of perovskite devices. To address this issue, a titanium nitride (TiN) layer is introduced as a robust corrosion-resistant coating between perovskite films and metal electrodes. By introducing TiN layer, a perovskite photodiode with dark current down to 3.25 × 10−11 A cm−2 is realized. Consequently, the TiN-based perovskite photodiode shows a specific detectivity of 1.21 × 1014 cm W−1 Hz1/2, which is approximately two orders of magnitude higher than that of the control device without a TiN layer. Under continuous illumination of a 520 nm green light for 576 000 cycles, the responsivity of the TiN-based photodetector remains at 94.27% of its initial value. The TiN-based photodetector exhibits superior stability under thermal stress. After aging at 85 °C for 572 h, the TiN-based photodetector retains 72% of its initial responsivity. Using the TiN-based photodiode, a perovskite image sensor containing 64 × 64 pixelated perovskite photodiodes is constructed over an amorphous silicon thin-film transistor (TFT) backplane. The perovskite image sensor exhibits real-time imaging capability and long-term stability for over 6 months. This study highlights the importance of using metallic nitrides to achieve high-performance and air-stable perovskite devices for optoelectronic applications.