Solution-processed Self-driven Bulk-heterojunction Photodetectors by Passivating with Polymers for Ultrasensitive Upconverters

As an optoelectronic device that integrates a display cell directly on a detecting cell, the upconverter can detect incident infrared light and convert it into visible light, and currently it becomes the research focus. However, the existed upconverters still show low sensitivity. In this paper, therefore, firstly lead sulfide quantum dots (PbS QDs) and poly(3-hexylthiophene) (P3HT) are blended in a suitable proportion as the hybrid active layer to fabricate self-driven bulk-heterojunctions (BHJs) photodetector, and then an organic light-emitting diode (OLED) was integrated onto it to form an upconverter. As a result, the upconverter ITO/ZnO/PbS:P3HT/TAPC/ CBP:Ir(ppy) ₃ /BCP/LiF /Al exhibited a high luminance of 18.8 cd·m ^-2 under 1.9 μW·cm ^-2 at 7V, as well as a low turn-on voltage of 2.4 V under 1.637 mW·cm ^-2 980 nm illumination. Further, the underlain mechanism for the ultrasensitive upconverter is discussed, and we believe the as-synthesized PbS:P3HT BHJs contribute to the separating and transporting of the photogenerated carriers.