A Self‐Powered Photodetector Based on MAPbI3 Single‐Crystal Film/n‐Si Heterojunction with Broadband Response Enhanced by Pyro‐Phototronic and Piezo‐Phototronic Effects

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2021-08, Vol.17 (32), p.e2101572-n/a
• Main Authors: Yang, Zheng, Wang, Huan, Guo, Linjuan, Zhou, Qing, Gu, Yansong, Li, Fangtao, Qiao, Shuang, Pan, Caofeng, Wang, Shufang
• Format: Article
• Language: English
• Subjects: Broadband; Coupling; Energy bands; Heterojunctions; MAPbI 3; Nanotechnology; Perovskites; Photometers; piezo‐phototronic effect; pyro‐phototronic effect; self‐powered photodetectors; single crystal films
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202101572

Pyro‐phototronic and piezo‐phototronic effect have shown their important roles for high performance heterojunction‐based photodetectors (PDs). Here, a coupling effect of pyro‐phototronic and piezo‐phototronic effect is utilized to fabricate a self‐powered and broadband PD based on the MAPbI3 single‐crystal film/n‐Si heterojunction. First, by using the pyro‐phototronic effect derived from MAPbI3, the maximum photoresponsivity of the self‐powered PD is 1.5 mA W−1 for 780 nm illumination, which is enhanced by more than 20 times in consideration of the relative peak‐to‐peak output current. Light‐induced temperature change in MAPbI3 film will create pyro‐charges distributed at heterojunction interface, resulting in a downward bending of the energy band, facilitating the transport of photon‐generated electrons and holes, and generating spike‐like output currents. Second, piezo‐phototronic effect is further introduced by applying vertical pressures onto the PD. With a vertical pressure of 155 kPa, the responsivity can be improved by more than 120% compared to the condition with no pressure. The overall enhancement is due to the piezo‐phototronic and pyro‐phototronic coupling effects which utilize the polarization charges to modulate the band structure of heterojunction. These results provide a promising approach to develop high‐performance self‐powered and broadband perovskite‐based PDs by coupling pyro‐phototronic and piezo‐phototronic effect. A self‐powered and broadband photodetector is fabricated based on MAPbI3 single‐crystal film/n‐Si heterostructure, which shows a best responsivity toward 780 nm laser illumination. By combing piezo‐phototronic and pyro‐phototronic coupling effects, the responsivity, response/recovery speed are greatly improved. This enhancement is due to that the light and pressure‐induced polarization charges can modulate the band structure of the heterojunction.