Dead zones in colloidal quantum dot photovoltaics: evidence and implications

Type
Article

Authors
Barkhouse, D. Aaron R.
Kramer, Illan J.
Wang, Xihua
Sargent, Edward H.

KAUST Grant Number
KUS-I1-009-21

Online Publication Date
2010-09-01

Print Publication Date
2010-09-13

Date
2010-09-01

Abstract
In order to fabricate photovoltaic (PV) cells incorporating light-trapping electrodes, flexible foil substrates, or more than one junction, illumination through the top-contact (i.e.: non-substrate) side of a photovoltaic device is desirable. We investigate the relative collection efficiency for illumination through the top vs. bottom of PbS colloidal quantum dot (CQD) PV devices. The external quantum efficiency spectra of FTO/TiO2/PbS CQD/ITO PV devices with various PbS layer thicknesses were measured for illumination through either the top (ITO) or bottom (FTO) contacts. By comparing the relative shapes and intensities of these spectra with those calculated from an estimation of the carrier generation profile and the internal quantum efficiency as a function of distance from the TiO2 interface in the devices, a substantial dead zone, where carrier extraction is dramatically reduced, is identified near the ITO top contact. The implications for device design, and possible means of avoiding the formation of such a dead zone, are discussed.

Citation
Barkhouse DAR, Kramer IJ, Wang X, Sargent EH (2010) Dead zones in colloidal quantum dot photovoltaics: evidence and implications. Optics Express 18: A451. Available: http://dx.doi.org/10.1364/OE.18.00A451.

Acknowledgements
This publication was supported in part by King Abdullah University of Science and Technology (KAUST), Award No. KUS-I1-009-21.

Publisher
The Optical Society

Journal
Optics Express

DOI
10.1364/OE.18.00A451

PubMed ID
21165075

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