Hybrid Graphene–Perovskite Phototransistors with Ultrahigh Responsivity and Gain
Y. Wang, Y. Zhang, Y. Lu, W. Xu, H. Mu, C. Chen, H. Qiao, J. Song, S. Li, B. Sun, Y. Cheng and Q. Bao
Advanced Optical Materials 3, 1389–1396 (2015)
Graphene is an attractive optoelectronic material for light detection because
of its broadband light absorption and fast response time. However, the relatively
low absorption cross-section, fast recombination rate, and the absence
of gain mechanism have limited the responsivity of pure graphene-based
phototransistor to ≈10 −2 A W −1 . In this work, a photoconductive gain of ≈10 9
electrons per photon and a responsivity of ≈6.0 × 10 5 A W −1 are demonstrated
in a hybrid photodetector that consists of monolayer graphene covered with
a thin layer of dispersive organolead halide perovskite (CH 3 NH 3 PbBr 2 I)
islands. The unprecedented performance is attributed to the effective charge
transfer and photogating effect, which were evidenced by photoluminescence
quenching, time-resolved photoluminescence decay, scanning near-fi eld
optical microscopy, and photocurrent mapping. Unlike previous report which
used perovskite bulk thin fi lm, the perovskite islands have low bulk recombination
rate of photogenerated carriers. The device also shows broad photodetection
spectral range from ultraviolet to visible (250–700 nm), affording new
opportunities for scalable UV detectors and imaging sensors.