High-Sensitivity p-n junction photodiodes based on PbS nanocrystal quantum dots

Pal, Bhola N., Robel, Istvan, Mohite, Aditya, Laocharoensuk, Rawiwan, Werder, Donald J. and Klimov, Victor I. (2012) High-Sensitivity p-n junction photodiodes based on PbS nanocrystal quantum dots. Advanced Functional Materials, 22 8: 1741-1748. doi:10.1002/adfm.201102532

Author Pal, Bhola N.
Robel, Istvan
Mohite, Aditya
Laocharoensuk, Rawiwan
Werder, Donald J.
Klimov, Victor I.
Title High-Sensitivity p-n junction photodiodes based on PbS nanocrystal quantum dots
Journal name Advanced Functional Materials   Check publisher's open access policy
ISSN 1616-301X
Publication date 2012-04
Sub-type Article (original research)
DOI 10.1002/adfm.201102532
Volume 22
Issue 8
Start page 1741
End page 1748
Total pages 8
Place of publication Weinheim, Germany
Publisher Wiley - V C H
Collection year 2013
Language eng
Abstract Chemically synthesized nanocrystal quantum dots (NQDs) are promising materials for applications in solution-processable optoelectronic devices such as light emitting diodes, photodetectors, and solar cells. Here, we fabricate and study two types of p-n junction photodiodes in which the photoactive p-layer is made from PbS NQDs while the transparent n-layer is fabricated from wide bandgap oxides (ZnO or TiO 2). By using a p-n junction architecture we are able to significantly reduce the dark current compared to earlier Schottky junction devices without reducing external quantum efficiency (EQE), which reaches values of up to ∼80%. The use of this device architecture also allows us to significantly reduce noise and obtain high detectivity (>10 12 cm Hz 1/2 W -1) extending to the near infrared past 1 μm. We observe that the spectral shape of the photoresponse exhibits a significant dependence on applied bias, and specifically, the EQE sharply increases around 500-600 nm at reverse biases greater than 1 V. We attribute this behavior to a "turn-on" of an additional contribution to the photocurrent due to electrons excited to the conduction band from the occupied mid-gap states.
Keyword PbS
Nanocrystal quantum dot
p-n junction
Mid-gap band
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
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