Self-assembled KCu7S4 nanowire monolayers for self-powered near-infrared photodetectors

Near infrared light (NIR) photodetectors based on one-dimensional semiconductor nanowires have generated considerable interest due to their practical application in versatile fields. We present a facile yet efficient approach to rationally integrating KCu7S4 semiconductor nanowires by the Langmuir-Blodgett (LB) technique. A self-powered near infrared (NIR) light photodetector is fabricated by transferring a close-packed KCu7S4 nanowire monolayer to the surface of a silicon wafer. The as-fabricated Si/KCu7S4 heterojunction with a close-packed and well-aligned nanowire array exhibits splendid photovoltaic performance when illuminated by NIR light, allowing the detection of NIR light without an exterior power supply. The photodetector exhibits a high sensitivity to NIR light (980 nm, 295.3 mu W cm(-2)) with responsivity (R) 15 mA W-1 and detectivity (D*) 2.15 x 10(12) cm Hz(1/2) W-1. Significantly, the device shows the capability to work under high pulsed light irradiation up to 50 kHz with a high-speed response (response time iota(r) 7.4 mu s and recovery time iota(f) 8.6 mu s). This facilitates the fabrication of low-cost and high-speed photodetectors and integrated optoelectronic sensor circuitry.