A flexible phototransistor with simultaneous high mobility and detectivity

Phototransistors have great application prospects in automotive vehicle, smart home, healthcare, imaging, and display. However, so far, there has been no report of flexible phototransistors that simultaneously achieve both high mobility and detectivity. Additionally, phototransistors are conventionally relied on thick channel layers and previous thin channel layers based devices only show poor performance. Here, we report flexible phototransistors based on ultrathin niobium-doped indium oxide (InNbO, 5 nm)/indium tin oxide (ITO, 3 nm) channel layers, which possess high mobility (49.21 cm2 V−1 s−1) and high detectivity (3.02 × 1014 Jones) simultaneously. Significantly, the devices offer a broad spectral responsivity (from violet to green emissions). We postulate that the high mobility can be ascribed to the diffusion of Sn atoms (from ITO) and conduction band offset (between InNbO and ITO), while the high detectivity originates from the low dark current. To illustrate the capabilities of flexible phototransistors, we demonstrate both a flexible active-matrix organic light-emitting diode display pixel circuit and an imaging system. Our approach unlocks new possibilities to achieve flexible phototransistors with superior performance, which suggest a great potential in next-generation flexible, stretchable, bendable, and low-cost electronics.