abstract
We report on highly efficient organic phototransistors (OPTs) based on thin-film/single-crystal planar bilayer junctions between 5,6,11,12-tetraphenyltetracene (rubrene) and [ 6,6]-phenyl-C-61-butyric acid methyl ester (PC61BM). The OPTs show good field-effect characteristics in the dark, with high hole-mobility (4-5cm(2) V-1 s(-1)), low-contact resistance (20 k Omega cm), and low-operating voltage (<= 5V). Excellent sensing capabilities allow for light detection in the 400-750 nm range, with photocurrent/dark current ratio as high as 4 x 10(4), responsivity on the order of 20AW(-1) at 27 mu Wcm(-2), and an external quantum efficiency of 52 000%. Photocurrent generation is attributed to enhanced electron and hole transfer at the interface between rubrene and PC61BM, and fast response times are observed as a consequence of the high-mobility of the interfaces. The optoelectronic properties exhibited in these OPTs outperform those typically provided by a-Si based devices, enabling future applications where multifunctionality in a single-device is sought. (C) 2015 AIP Publishing LLC.
keywords
FIELD-EFFECT TRANSISTORS; N-TYPE; QUANTUM EFFICIENCY; PHOTODETECTORS; MOBILITY; HETEROSTRUCTURE; SEMICONDUCTORS; PHOTORESPONSE; INTERFACES; GROWTH
subject category
Physics
authors
Pinto, RM; Gouveia, W; Neves, AIS; Alves, H
our authors
Helena Alves
Principal Researcheracknowledgements
The authors acknowledge the financial support from Fundacao para a Ciencia e Tecnologia (FCT) through Contract Nos. SFRH/BPD/84820/2012, IF/01088/2014, and funding through the IN and CICECO Associated Laboratories. A.N. thanks EPSRC for grant EP/M001024/1. The authors thank A. Kholkin (CICECO) for characterizing the PCBM films.