Photojunction Field-Effect Transistor Based on a Colloidal Quantum Dot Absorber Channel Layer


Adinolfi, Valerio
Kramer, Illan J.
Labelle, André J.
Sutherland, Brandon R.
Hoogland, S.
Sargent, Edward H.

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© 2015 American Chemical Society. The performance of photodetectors is judged via high responsivity, fast speed of response, and low background current. Many previously reported photodetectors based on size-tuned colloidal quantum dots (CQDs) have relied either on photodiodes, which, since they are primary photocarrier devices, lack gain; or photoconductors, which provide gain but at the expense of slow response (due to delayed charge carrier escape from sensitizing centers) and an inherent dark current vs responsivity trade-off. Here we report a photojunction field-effect transistor (photoJFET), which provides gain while breaking prior photoconductors' response/speed/dark current trade-off. This is achieved by ensuring that, in the dark, the channel is fully depleted due to a rectifying junction between a deep-work-function transparent conductive top contact (MoO3) and a moderately n-type CQD film (iodine treated PbS CQDs). We characterize the rectifying behavior of the junction and the linearity of the channel characteristics under illumination, and we observe a 10 μs rise time, a record for a gain-providing, low-dark-current CQD photodetector. We prove, using an analytical model validated using experimental measurements, that for a given response time the device provides a two-orders-of-magnitude improvement in photocurrent-to-dark-current ratio compared to photoconductors. The photoJFET, which relies on a junction gate-effect, enriches the growing family of CQD photosensitive transistors.

Adinolfi V, Kramer IJ, Labelle AJ, Sutherland BR, Hoogland S, et al. (2015) Photojunction Field-Effect Transistor Based on a Colloidal Quantum Dot Absorber Channel Layer. ACS Nano 9: 356–362. Available:

The authors would like to acknowledge E. Palmiano, R. Wolowiec, and D. Kopilovic for technical assistance and guidance. Thanks to C. Maragliano for the valuable discussions. This publication is based in part on work supported by Award KUS-11-009-21 made by King Abdullah University of Science and Technology (KAUST), by the Ontario Research Fund–Research Excellence Program, and by the Natural Sciences and Engineering Research Council (NSERC) of Canada.

American Chemical Society (ACS)

ACS Nano


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