Methylammonium lead triiodide (CH3NH3PbI3) perovskite is an emerging low-cost, solution processable material which attracts great interest for enabling the fabrication of high performance optoelectronic devices such as solar cells, room temperature lasers and light emitting diodes. Although charge traps are deleterious defects for photovoltaic devices, they are beneficial to realize sensitive detectors because, by increasing the electron-hole recombination time, they increase the device photoconductive gain. Here we report perovskite thin film devices with large density of hole traps induced by annealing surface decomposition which are characterized by a photoconductive gain in excess of 400 at a very low bias (-1V). The photogenerated holes, which are trapped at the perovskite-anode interface, are identified as the key enabling factor for such high gain. The devices exhibits a peak responsivity of 242 A·W-1 and a specific detectivity > 1014 cm·Hz1/2·W-1 from 350 nm to 770 nm, which is over ten times higher than for commercial crystalline Si photodiodes. Thanks to the high gain we believe that perovskites are a promising new family of photodetector materials which combine low cost, low bias and room-temperature operation.
Citation: Advanced Materials
Pub Type: Journals