Enhanced photodetection in organic semiconductor single crystal sensitized by a tailored synergistic absorption of capsule-shaped chlorophyll derived CQDs

Abstract

Organic single-crystal phototransistors have emerged as one of the most promising light signal detectors for their minimal defects, high mobility and light sensitivity. However, fully exploiting their advantages in advanced flexible optoelectronic applications remains great difficulty and challenging due to the lack of efficient methods for upgrading the photoresponse of delicate organic crystalline materials. Herein, we developed a capsule-shaped chlorophyll derived carbon quantum dots (Chl-CQDs) to enhance the single-crystal photodetection. Through a multi-site carbonization of chlorophyll peripheral substituents, the CQDs were produced around the chlorophyll tetrapyrrole macrocyclicvia. It makes Chl-CQDs combine the light absorption advantages of chlorophyll and CQDs, and exhibit an amazing synergistic absorption behavior. Compared to pristine devices of 2,6-diphenyl anthracene (DPA), the key figures of merit such as P, R, and D* of the Chl-CQDs/DPA heterophototransistors are improved by over 6000 times, 5 times, and 200 times, respectively. Additionally, an ultra fast charge transfer dynamics (τrise = 35 ms and τdecay = 45 ms) is observed at such unique type II heterointerface. These results not only offer a new approach for improving the photoresponse of single crystal organic phototransistors, but also make it possible to be superior to that of silicon-based devices.