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.
| Original language | English |
|---|---|
| Pages (from-to) | 1741-1748 |
| Number of pages | 8 |
| Journal | Advanced Functional Materials |
| Volume | 22 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - Apr 24 2012 |
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Keywords
- detectivity
- mid-gap band
- nanocrystal quantum dot
- p-n junction
- PbS
- photodetector
ASJC Scopus subject areas
- Biomaterials
- Electrochemistry
- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials
Cite this
High-Sensitivity p-n junction photodiodes based on Pbs nanocrystal quantum dots. / Pal, Bhola N.; Robel, Istvan; Mohite, Aditya; Laocharoensuk, Rawiwan; Werder, Donald J.; Klimov, Victor I.
In: Advanced Functional Materials, Vol. 22, No. 8, 24.04.2012, p. 1741-1748.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - High-Sensitivity p-n junction photodiodes based on Pbs nanocrystal quantum dots
AU - Pal, Bhola N.
AU - Robel, Istvan
AU - Mohite, Aditya
AU - Laocharoensuk, Rawiwan
AU - Werder, Donald J.
AU - Klimov, Victor I
PY - 2012/4/24
Y1 - 2012/4/24
N2 - 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.
AB - 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.
KW - detectivity
KW - mid-gap band
KW - nanocrystal quantum dot
KW - p-n junction
KW - PbS
KW - photodetector
UR - http://www.scopus.com/inward/record.url?scp=84859847145&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84859847145&partnerID=8YFLogxK
U2 - 10.1002/adfm.201102532
DO - 10.1002/adfm.201102532
M3 - Article
VL - 22
SP - 1741
EP - 1748
JO - Advanced Functional Materials
JF - Advanced Functional Materials
SN - 1616-301X
IS - 8
ER -