Solution-processed PbS colloidal quantum dots/PCBM based photodetector for multispectral detection

Photodetectors convert optical signals into electrical signals and have found many important applications ranging from environmental monitoring to communication systems. At present, most photodetectors are based on either bulk materials or epitaxially grown materials (such as InSb and HgCdTe), which limit its widespread applications due to relatively high fabrication cost. However, photodetector based on organic polymer/colloidal quantum dots (CQDs) can provide a low-cost alternative. In this paper, a broadband photodetector consisting of organic polymer phenyl-c61-butyric acid methyl ester (PCBM) and PbS CQDs was fabricated. Combining the advantages of PbS CQDs and organic polymer PCBM, the device demonstrated good spectral response ranging from the UV to the NIR with a maximum responsivity and detectivity of 0.3 A/W and 6.6 × 1011 Jones, respectively, under illumination of 850 nm incident light. The device can be fabricated on almost any substrate due to the solution-processibility of CQDs. Furthermore, the use of organic polymer substrate can significantly reduce the cost of device and broaden its applications (such as in flexible electronics). This work provides a simple and efficient strategy to fabricate photodetector that exhibits multi-band response at relatively low-cost.