High performance solution-processed infrared photodiodes ITO/ZnO/PbSxSe1−x/Au, in which ternary PbSxSe1−x colloidal quantum dots acts as the active layer and ZnO interlayer acts as electron-transporting layer, have been demonstrated.

Narrow band-gap colloidal quantum dots (CQDs) are promising materials for flexible electronic, such as infrared light photodetectors and solar cells.

Infrared (IR) emission lead selenide (PbSe) quantum dots (QDs) have gained considerable attention in the last decade due to their potential applications in optoelectronic devices. However, the comprehensive applications of PbSe QDs have not been realized yet due to their high susceptibility to oxidation in air. In this paper, we demonstrate the stability enhancement of PbSe colloidal QDs via a post-synthetic ammonium chloride treatment and its applications in a solution-processed high-performance IR photodetector with a field-effect transistor (FET) configuration by reversely fabricating the PbSe active layer and polymethylmethacrylate (PMMA) dielectric layer. The responsivity and the specific detectivity of the FET-based photodetector Au(source, drain)/PbSe(52 nm)/PMMA(930 nm)/Au(gate) reached 64.17 mA W(-1) and 5.08 × 10(10) Jones, respectively, under 980 nm laser illumination with an intensity of 0.1 mW cm(-2). Therefore, it provides a promising way to make a high-sensitivity near-IR/mid-IR photodetector.

In this paper, the influence of the active layer nanomorphology on device performance for ternary PbS(x)Se(1-x) quantum dot-based solution-processed infrared photodetector is presented. Firstly, ternary PbS(x)Se(1-x) quantum dots (QDs) in various chemical composition were synthesized and the bandgap of the ternary PbS(x)Se(1-x) QDs can be controlled by the component ratio of S/(S + Se), and then field-effect transistor (FET) based photodetectors Au/PbS0.4Se0.6:P3HT/PMMA/Al, in which ternary PbS0.4Se0.6 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 PbS0.4Se0.6 QDs (K = M(P3HT):M(QDs)) 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(-1) and 1.02 × 10(10) Jones, respectively, at low V(DS) = -10 V and V(G) = 3 V under 980 nm laser with an illumination intensity of 0.1 mW cm(-2). By measuring the atomic force microscopy phase images of PbS0.4Se0.6: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.

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In this letter, we presented a solution-processed photodetector with a configuration of field-effect transistor (FET) ITO/poly(4-vinylphenol) (PVP)/poly(3-hexylthiophene) (P3HT): poly(methyl methacrylate) (PMMA)/Au in which PVP acts as a dielectric layer and different PMMA content (20 wt.% ∼ 60 wt.%) in P3HT as active layer. The best electrical property of the photodetector under no illumination was obtained with 20 wt.% PMMA content and the maximum ON-OFF current ratio and hole mobility of the as-prepared devices are 329 and 1.6 × 10 −3 cm 2 /V · s, respectively. Under illumination with wavelengths varying from 350 to 650 nm, however, the 50 wt.% PMMA content device demonstrated highest performance, showing a maximum photoresponsivity of 166.45 mA/W under 65 µW/cm 2 of 600-nm illumination. Atom force microscope (AFM) phase images of P3HT:PMMA film certify the phase separation between P3HT and PMMA, as well as the crystallinity improvement of P3HT film after blending PMMA. The performance of FET-based photodetector under illumination is discussed. Index Terms-Semiconductor-insulator blends, phase separation, photodetector, poly(3-hexylthiophene) (P3HT), poly(methyl methacrylate) (PMMA).

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