Near infrared photodetectors based on sub-gap absorption in organohalide perovskite single crystals

• Published in: Laser & photonics reviews Vol. 10; no. 6; pp. 1047 - 1053
• Main Authors: Lin, Qianqian, Armin, Ardalan, Burn, Paul L., Meredith, Paul
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01.11.2016; Wiley Subscription Services, Inc
• Subjects: Absorption; Architecture; Devices; Electric potential; near infrared; Optoelectronics; organohalide perovskite; Perovskites; photodetector; Photoelectric effect; Single crystals; sub-bandgap photoresponse
• ISSN: 1863-8880; 1863-8899
• DOI: 10.1002/lpor.201600215

Organohalide perovskite optoelectronics based upon large (mm‐sized) single crystals present exciting opportunities for new device platforms and fundamental studies. Herein, we report CH3NH3PbBr3 and CH3NH3PbI3 single crystals prepared via an inverse temperature crystallization method with strong near infrared photoresponses significantly below the optical gap. Light intensity dependent photocurrent measurements reveal the photoresponse is not a two‐photon phenomenon, but rather is derived from a linear mechanism. The effect (including responsivity and speed) is enhanced in a photoresistor architecture, indicating that the photoresponse is due to absorption into surface trap states in the crystal. Without any optimisation, respectable NIR responsivities at room temperature of ∼10‐2 A W−1 at a low 1V bias operating voltage are achieved. These results again demonstrate the remarkable potential of organohalide perovskites as light sensing materials, and the possibilities for engineering a new class of single crystal‐based optoelectronics. A sub‐bandgap photoresponse was observed from organohalide perovskite single crystal‐based photodiodes due to the trap‐state absorption. An enhanced responsivity and speed was acheived by using a photoresistor architecture to harness the crystal surface states more effectively.