Filter-free selective light monitoring by organic field-effect transistor memories with a tunable blend charge trapping layer
ACS applied materials & interfaces | 10 Oct 2019
LX Zhang, X Gao, JJ Lv, YN Zhong, C Xu, JL Xu and SD Wang
Integration of selective photodetection and signal storage in a single device, such as organic field-effect transistor (OFET) memories, meets the demands for radiation monitoring and protection. A new strategy is developed to achieve the filter-free and selective light monitoring by adopting a solution-processed blend charge trapping layer in OFET memories, where the charge trapping layer is composed of phenyl-C61-butyric acid methyl ester (PCBM) dispersed in a polymer electret thin film. The OFET memory without PCBM shows response only to ultraviolet (UV) light, whereas the spectral response edges are extended to the visible and near-infrared (NIR) regions in the corresponding devices with relatively low and high content of PCBM in the charge trapping layer, respectively. A set of OFET memories with different PCBM content are used to qualitatively evaluate the light composition in an optical source. The tunable spectral response in the OFET memories is ascribed to the additional photo-assisted charge trapping path depending on the blend ratio in the charge trapping layer. This mechanism may inspire alternative approaches to organic-based optical sensing and monitoring in flexible and wearable electronics.
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