Retina-inspired controllable neuromorphic vision organic sensors with ultraweak ultraviolet detection

Abstract Sensing and recognizing invisible ultraviolet (UV) light is vital for exploiting advanced artificial visual perception system with tetrachromacy. However, due to the uncertainty of the natural environment, the UV signal is very hard to be detected and perceived. Here, we report a controllable UV-ultrasensitive neuromorphic vision sensor (NeuVS) that uses organic phototransistors (OPTs) as working unit to integrate sensing, memory and processing functions. Benefiting from asymmetric molecular structure and unique UV absorption of the active layer, the as fabricated UV-ultrasensitive NeuVS can detect the illumination intensity of 370 nm UV-light as low as 31 nw cm-2 and exhibit one of the best optical figures of merit in UV-sensitive neuromorphic vision sensors. Furthermore, the NeuVS array exbibits good image sensing and memorization capability due to its ultrasensitive optical detection and large density of charge trapping states. In addition, the wavelength-selective response and multi-level optical memory properties are utilized to construct an artificial neural network (ANN) for extraction and identification of invisible UV information. The NeuVS array can extract UV handwritten digit from the original color image by filtering red, green and blue (RGB) noise, and significantly improve the recognition accuracy from 46% to 90%.