N-Type Conjugated Polymer as Multi-Functional Interfacial Layer for High-Performance and Ultra-Stable Self-Powered Photodetectors Based on Perovskite Nanowires

High-performance and long-term stable self-powered photodetectors (PDs) based on methylammonium lead iodide nanowires (NWs) are demonstrated by incorporating n-type conjugated polymer poly{2,5-bis(2-dodecylhexadecyl)-3,6-di(thiophen-2-yl)pyrrolo-[3,4-c]pyrrole-1,4(2H,5H)-dione-alt-(E)-1,2-bis(3-cyanothiophen-2-yl)ethene} (DPP-CNTVT) as multi-functional interfacial layer. Incorporating DPP-CNTVT with abundant Lewis base functional groups can effectively passivate under-coordinated Pb2+ defects, enabling perovskite NWs to exhibit remarkable stability and optoelectronic properties. Meanwhile, high electron mobility, together with the proper energy level of DPP-CNTVT, makes it ideal for use as an electron transport layer. Particularly, by taking advantage of the low bandgap of DPP-CNTVT, the utilization of low energy photons can be improved. The resulting PDs exhibit responsivity up to 0.50 A W-1, specific detectivity approaching 10(14) Jones, and a wide linear dynamic range of nearly 265 dB under zero bias operation, which represent the best results ever reported for self-powered perovskite PDs. More encouragingly, with the incorporation of an appropriate encapsulation layer, nearly 90% of the initial detectivity of PDs can be secured after 15 300 h of continuous operation in ambient conditions. The application of NWs PDs for solution-processed reflective-mode pulse oximetry is also demonstrated. This study provides valuable insights into developing efficient and ultra-stable self-powered perovskite PDs through interfacial engineering, which can accelerate the practical applications of this emerging technology.

Automated summary

High-performance and long-term stable self-powered photodetectors based on methylammonium lead iodide nanowires are demonstrated by incorporating a multi-functional interfacial layer DPP-CNTVT. The PDs exhibit a high responsivity, specific detectivity, and wide linear dynamic range, with nearly 90% of the initial detectivity secured after continuous operation for 15,300 hours in ambient conditions. This study provides valuable insights into developing efficient and ultra-stable self-powered perovskite PDs through interfacial engineering.