High-Performance Organic Phototransistors Based on D18, a High-Mobility and Unipolar Polymer

Organic optoelectronics has progressed excitingly in recent years, mainly due to the innovation of donor and acceptor systems. Organic photodetectors based on novel semiconductor materials and well-designed device architectures have also been reported with improved device performance. However, most of them were photodiodes, and it is challenging to integrate them into the well-established readout circuits. Organic phototransistors are mainly based on the hybrid strategy, composed of either hybrid films or multilayer device structures, which complicates charge transfer and charge transport. Most of the organic devices also suffer from poor stability. In this work, we introduce a recently developed p-type copolymer, D18, to fabricate high-performance phototransistors. D18 possesses excellent charge generation, high mobility, and unipolar charge transport, which fulfill the generic design rule of organic phototransistors. The optimized phototransistors based on D18 exhibited extremely low dark current (∼10 pA) and noise (∼10 fA/Hz1/2), a high detectivity of 4 × 1013 Jones, a swift response of <5 ms, and excellent device stability. We also demonstrated flexible phototransistors with decent performance metrics, indicating great potential for next-generation solution-processed photodetectors and flexible electronic devices.