Blended phase separation strategy for seamless integration of ultrathin crystalline channels and charge trapping layers toward multimode neuromorphic optoelectronics

Abstract

Organic ultrathin crystals, comprising monolayers or a few molecular layers, exhibit outstanding optoelectronic properties and have shown great promise for constructing advanced functional neuromorphic devices. However, scalable growth of high-quality organic ultrathin crystals and their seamless concurrent integration with charge trapping layers for multi-mode neuromorphic devices, that required in future high-density neuromorphic integration, remain challenging. Here, we present a scalable one-step fabrication strategy based on solution shearing, where spontaneous vertical phase separation of a small-molecule/polymer (Ph-BTBT-10/PS) blend enables the simultaneous formation of high-quality ultrathin Ph-BTBT-10 crystals and an electret PS charge-trapping layer. The PS electret layer serves a dual function: it facilitates the formation of ultrathin, highly ordered Ph-BTBT-10 crystals; meanwhile, its gate-tunable electron-trapping capability enables dynamic switching between photo-switching and photo-synaptic modes within a single device. As a photodetector, the device exhibits exceptional performance, including a responsivity of 4.7 × 10⁴ A/W, specific detectivity of 2.2 × 10¹⁷ Jones, and photosensitivity of 1.5 × 10⁸. Under negative gate bias, light-triggered switching behavior enables logic gate demonstration, while under positive gate modulation, photonic synaptic behavior successfully emulates key biological functions, including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), short-term plasticity (STP) to long-term plasticity (LTP) transition, dynamic learning-forgetting processes, and image processing. Moreover, the system exhibits excellent compatibility with low-voltage flexible substrates and further demonstrates its application in low-consumption flexible neuromorphic devices. This work provides a scalable route toward high-performance, multifunctional neuromorphic optoelectronics based on organic ultrathin crystals, and advances the integration of flexible electronics and brain-inspired computing.