Lead-Free Perovskite Nanowire Photodetector with Improved Stability

Organohalide lead perovskite materials have attracted enormous attention due to their intriguing properties such as long diffusion length, tunable band gap, and excellent light absorption. Recently, one-dimensional (1D) nanostructures for organic perovskites have opened new horizons for optoelectronic devices. In fact, 1D nanostructures has the exciting feature of guided carrier transportation in one direction, which makes them suitable candidates for many devices like diodes and transistors. Aside from all these advantages of organohalide Lead perovskites, one of the concern about these materials is toxicity of Lead (Pb) metal. Previously only a few works have tried to cope up with toxicity issue by replacing the lead metal with other metal such as Tin (Sn). These works suggested that orgahalide Tin Perovskite materials can solve the toxicity and increase photo conversion abilities over organic lead perovskites but their stability is worse than Lead perovskites. MASnI3 are not stable in ambient air due to oxidation and chemical instability of tin metal in required 2+ oxidation state, however it is worth noting that tin perovskite stability can be improved by suitable packaging techniques. Here, we report fabrication of tin perovskite 1D nanowires based photodetector with enhanced stability by using a new approach of Chemical Vapor deposition (CVD) for the first time. So far, 1D nanostructures of tin perovskite based devices have not been explored as per our knowledge. Ordered and uniform arrays of tin perovskite nanowires have been grown up inside Anodized Aluminum Oxide (AAO) membrane using tin metal as a precursor, which is electrodeposited at the bottom of AAO nanochannels. These nanowires come up with feature of geometry tune ability (Radius and length of nanowire can be tuned) by altering geometry and shape of AAO template. The second advantage of this work is enhanced stability of grown tin perovskite nanowires inside AAO template. AAO template not only guides the nanowire growth direction but also provides protection from ambient air condition. The results of stability test of tin perovskite thin film compared with tin perovskite nanowires grown inside AAO show the enhanced stability of tin perovskite nanowires. Based on tin perovskite nanowires, a photodetector device is realized with 1010 Jones detectivity and enhanced responsivity measures using Aluminum and Gold as electrodes. Overall, this work presents low cost fabrication of an efficient tin perovskite nanowires based photodetector with improved stability.