abstract
Atomically thin materials such as graphene are uniquely responsive to charge transfer from adjacent materials, making them ideal charge-transport layers in phototransistor devices. Effective implementation of organic semiconductors as a photoactive layer would open up a multitude of applications in biomimetic circuitry and ultra-broadband imaging but polycrystalline and amorphous thin films have shown inferior performance compared to inorganic semiconductors. Here, the long-range order in rubrene single crystals is utilized to engineer organic-semiconductor-graphene phototransistors surpassing previously reported photogating efficiencies by one order of magnitude. Phototransistors based upon these interfaces are spectrally selective to visible wavelengths and, through photoconductive gain mechanisms, achieve responsivity as large as 10(7) A W-1 and a detectivity of 9 x 10(11) Jones at room temperature. These findings point toward implementing low-cost, flexible materials for amplified imaging at ultralow light levels.
keywords
ORGANIC SEMICONDUCTORS; SINGLE-CRYSTAL; QUANTUM DOTS; HIGH-GAIN; HYBRID; DEVICES; PHOTODETECTORS; PHOTORESPONSE; NOISE
subject category
7
authors
Jones, GF; Pinto, RM; De Sanctis, A; Nagareddy, VK; Wright, CD; Alves, H; Craciun, MF; Russo, S
our authors
Helena Alves
Principal Researcheracknowledgements
S.R. and M.F.C. acknowledge financial support from EPSRC (Grant 464 Nos. EP/J000396/1, EP/K07160/1, EP/K010050/1, EP/G036101/1, EP/M001024/1, and 465 EP/M002438/1), from Royal Society international Exchanges Scheme 2012/R3 and 466 2013/R2 and from European Commission (No. FP7-ICT-2013-613024-GRASP). The authors would like to thank Paul Wilkins for technical assistance in designing and building the vacuum chamber probe station used for all photocurrent measurements and Dr. Dominique J. Wehenkel and Jake. D. Mehew for fruitful discussions and for assisting with photocurrent/PL measurements.