Organic Visible-Blind Ultraviolet Photodiodes and Pixel-Array Imagers Based on [1]Benzothieno[3,2-b]Benzothiophene (BTBT) Derivatives

Abstract

Visible-blind ultraviolet (VBUV) photodetectors are designed for UV detection without responding to visible light, thus having many applications in communications, flame detection, environment monitoring, and astronomy. Herein, an organic device concept based on the bulk heterojunction (BHJ) photodiode is presented for high-performance VBUV photodetection and imaging. The BHJ, comprised of an organic electron donor, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT), and an electron acceptor, indene-C₆₀ bisadduct (ICBA), shows efficient generation and transport of free charges upon UV irradiation. The organic photodiode (OPD) delivers exceptional VBUV photodetection performance. At a low voltage of −0.5 V, the device exhibits a wide linear dynamic range of 98.15 dB. Furthermore, the OPD can detect ultra-low light intensities down to 0.58 µW cm⁻² with a high photoresponsivity of 0.12 A W⁻¹ and specific detectivity of 2.75 × 10¹² Jones. More importantly, by integrating the OPD with a readout integrated circuit, the pixel-array organic VBUV imager is demonstrated to have high-quality imaging capability. The results reveal a novel strategy to design VBUV photodetectors and imagers with balanced performance, cost, area, flexibility, and power consumption.