Solution-processable two-dimensional hexagonal copper indium selenide semiconductors

Abstract

Solution-processable two-dimensional semiconductors could be used for the cost-effective fabrication of large-area electronic devices. However, compared with two-dimensional materials made using high-temperature chemical vapour deposition methods, they exhibit much lower electrical performance. Here we report the solution-processable fabrication of wafer-scale two-dimensional layered copper indium selenide (CuIn5Se8) semiconductors with high mobility values. The air-stable solution-based ink formulation and film assembly allow four-inch CuIn5Se8 thin films to be deposited in the ambient air environment. By elucidating the impact of a reversible water adsorption process on electrical performance, a moderate annealing step is developed to eliminate surface water molecules. The resulting CuIn5Se8 transistors exhibit an average electron mobility of 155 cm2 V−1 s−1 and an on/off ratio of 107 with a small current hysteresis. Furthermore, the robust transistor operation and small device-to-device variation enable the integration of over 100 transistors into a prototypical microprocessor that can process digital signals at a frequency of 2.2 kHz. Wafer-scale and air-stable semiconducting films of two-dimensional copper indium selenide can be made from monolayer ink deposition and annealing, creating transistors with an average mobility of 155 cm2 V−1 s−1 and a microprocessor containing over 100 devices.