Influence of the active layer nanomorphology on device performance for ternary PbSSe quantum dots based solution-processed infrared photodetector

In this paper, the influence of the active layer nanomorphology on device performance for ternary PbSSe quantum dot-based solution-processed infrared photodetector is presented. Firstly, ternary PbSSe quantum dots (QDs) in various chemical composition were synthesized and the bandgap of the ternary PbSSe QDs can be controlled by the component ratio of S/(S + Se), and then field-effect transistor (FET) based photodetectors Au/PbSSe:P3HT/PMMA/Al, in which ternary PbSSe QDs doped with poly(3-hexylthiophene) (P3HT) act as the active layer and poly(methyl methacrylate) (PMMA) as the dielectric layer, were presented. By changing the weight ratio of P3HT to PbSSe QDs (K = M:M) in dichlorobenzene solution, we found that the device with K = 2:1 shows optimal electrical property in dark; however, the device with K = 1:2 demonstrated optimal performance under illumination, showing a maximum responsivity and specific detectivity of 55.98 mA W and 1.02 ×10 Jones, respectively, at low V = -10 V and V = 3 V under 980 nm laser with an illumination intensity of 0.1 mW cm. By measuring the atomic force microscopy phase images of PbSSe:P3HT films in different weight ratio K, our experimental data show that the active layer nanomorphology has a great influence on the device performance. Also, it provides an easy way to fabricate high performance solution-processed infrared photodetector.