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 weak 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 article, therefore, first lead sulfide (PbS) quantum dots (QDs), and poly(3-hexylthiophene) (P3HT) are blended in a suitable proportion as the hybrid active layer to fabricate self-driven bulk-heterojunction (BHJ) photodetector, and then, an organic light-emitting diode (OLED) is directly integrated onto it to form an upconverter. As a result, the upconverter ITO/ZnO/PbS:P3HT/TAPC/CBP:Ir(ppy)3/BCP/LiF/Al exhibits a high luminance of 18.8 cd/m2 under 1.9~\mu W/cm2 at 7 V, as well as a low turn-on voltage of 2.4 V under 1.637 mW/cm ^{{2}}~980 nm illumination. Furthermore, the underlain mechanism for the ultrasensitive upconverter is discussed, and we believe that the as-synthesized PbS:P3HT BHJ contributes to the efficient separation and transportion of the photogenerated carriers.