Understanding and Countering Illumination-Sensitive Dark Current: Toward Organic Photodetectors with Reliable High Detectivity

Continuously enhanced photoresponsivity and suppressed dark/noise current coinbinatorially lead to the recent development of high-detectivity organic photodetectors with broadband sensing competence. Despite the achievements, reliable photosensing enabled by organic photodetectors (OPDs) still faces challenges. Herein, we call for heed over a universal phenomenon of detrimental sensitivity of dark current to illumination history in high-performance inverted OPDs. The phenomenon, unfavorable to the attainment of high sensitivity and consistent figures-of-merit, is shown to arise from exposure of the commonly used electron transport layer in OPDs to high-energy photons and its consequent loss of charge selectivity via systematic studies. To solve this universal problem, double layer tin oxide as an alternative electron transport layer is demonstrated, which not only eliminates the inconsistency between the initial and after-illumination dark current characteristics but also preserves the low magnitude of dark current, good external quantum efficiency, and rapid transient response.

Automated summary

The universal problem of detrimental sensitivity of dark current to illumination history in high-performance inverted OPDs poses challenges to achieving high sensitivity and consistent figures-of-merit. Through systematic studies, it has been shown that the exposure of commonly used electron transport layer to high-energy photons leads to the loss of charge selectivity, hindering the attainment of high sensitivity and consistent performance characteristics. The use of double layer tin oxide as an alternative electron transport layer has been demonstrated to solve this issue.