Hybrid Graphene–Perovskite Phototransistors with Ultrahigh Responsivity and Gain

Abstract

material. Graphene has been demonstrated to be an effective channel material for phototransistor because of its broadband light absorption, fast response time, and ultrahigh carrier mobility. [1][2][3] However, the relatively low absorption cross-section, fast recombination rate and the absence of gain mechanism that can generate multiple charge carriers from one incident photon have limited the responsivity of pure graphene-based phototransistor [ 4,5 ] to ≈10 −2 A W −1 which is much lower than that of commercial Si photodiode. [ 6 ] So far, the rapid development of graphene-based photodetection has focused on enhancement of the light absorption in graphene by variant approaches such as plasmonic coupling [ 7 ] and microcavity confi nement. [8][9][10] Nevertheless, a key to ultrasensitive graphene-based photodetection is the implementation of photoconductive gain which could afford the ability to generate multiple electrical carriers per single incident photon.Until now, the photoconductive gain for improved sensitivity has not been observed in pure grapehene-based photodetector. Alternatively, the hybridization of graphene with a gain material or the formation of a heterostructure has been proved to be an effective approach to enhance the photodetection performance. For example, the mixtures of graphene with TiO 2 [ 11 ] or quantum dots [ 12 ] have shown greatly improved photoconductive gain but the synthesis of gain material needs complicated processes. The formation of vertical heterostructure of graphene and layered transition metal dichalcogenides (TMDs) such as MoS 2 , [ 13,14 ] WS 2 , [ 15 ] and WSe 2 [ 16,17 ] can achieve very high quantum effi ciency upon light illumination due to effective photoexcited carrier separation at the interface. However, the fabrication of these devices is expensive and lack of scalability as it demands delicately controlled sample transfer technique which has low-yield and multiple lithography procedures.Recently, mixed organic-inorganic halide perovskites have emerged as a new class of light harvesting material for highly effi cient solar cells with confi rmed effi ciency of 19.2%. [ 18 ] This family of perovskite materials take the form of ABX 3 (A = CH 3 NH 3 + ; B = Pb 2+ ; X = Cl − /I − /Br − ) and show large absorption cross-section, long photocarrier diffusion length, and high charge carrier mobility. [ 19 ] These unique photoelectrical properties enable many photonic and optoelectronic applications such as random lasing, [ 20 ] light emitting diode, [ 21 ] and 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 g...

Solution-processed semiconductors for next-generation photodetectors

“…The photoconductive gain under such conditions is given by, reported, where CH3NH3PbBr2I provide visible sensitization. 81,82 We note that pure MHP phototransistors based on CH3NH3PbI3-xClx perovskites have also been explored, that exhibited ambipolar behaviour with sub 10 µs time response operation but gains below 10 3 . 83 The absence of bandgap in graphene precludes however full exploitation of this hybrid architecture since the transport channel cannot be totally closed, which ultimately results in significant dark currents.…”

Hybrid graphene tunneling photoconductor with interface engineering towards fast photoresponse and high responsivity

“…For detailed comparison, we have summarized the figures of merit (response time and responsivity) for some previously reported hybrid graphene photoconductors/phototransistors and our device, as shown in Figure 5b. [10][11][12][13][14][15][16][17][18][19]…”

Ultrahigh Responsivity and Detectivity Graphene–Perovskite Hybrid Phototransistors by Sequential Vapor Deposition

“…This material has been widely applied in photovoltaics24252627, light-emitting devices272829, and photodetectors30313233. For photodetection, Lee et al .…”