Nanographene-Based Heterojunctions for High-Performance Organic Phototransistor Memory Devices.

Abstract

Organic phototransistors can enable many important applications such as nonvolatile memory, artificial synapses, and photodetectors in next-generation optical communication and wearable electronics. However, it is still a challenge to achieve a big memory window (threshold voltage response ∆Vth ) for phototransistors. Here, a nanographene-based heterojunction phototransistor memory with large ∆Vth responses is reported. Exposure to low intensity light (25.7µWcm-2 ) for 1 s yields a memory window of 35V, and the threshold voltage shift is found to be larger than 140V under continuous light illumination. The device exhibits both good photosensitivity (3.6 × 105 ) and memory properties including long retention time (>1.5 × 105 s), large hysteresis (45.35V), and high endurance for voltage-erasing and light-programming. These findings demonstrate the high application potential of nanographenes in the field of optoelectronics. In addition, the working principle of these hybrid nanographene-organic structured heterojunction phototransistor memory devices is described which provides new insight into the design of high-performance organic phototransistor devices.