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Title: Improving Performance in Colloidal Quantum Dot Solar Cells by Tuning Band Alignment through Surface Dipole Moments

Abstract

Colloidal quantum dots (CQDs) have received recent attention for low cost, solution processable, high efficiency solid-state photovoltaic devices due to the possibility of tailoring their optoelectronic properties by tuning size, composition, and surface chemistry. However, the device performance is limited by the diffusion length of charge carriers due to recombination. In this work, we show that band engineering of PbS QDs is achievable by changing the dipole moment of the passivating ligand molecules surrounding the QD. The valence band maximum and conduction band minimum of PbS QDs passivated with three different thiophenol ligands (4-nitrothiophenol, 4-fluorothiophenol, and 4-methylthiophenol) are determined by UV–visible absorption spectroscopy and photoelectron spectroscopy in air (PESA), and the experimental results are compared with DFT calculations. These band-engineered QDs have been used to fabricate heterojunction solar cells in both unidirectional and bidirectional configurations. The results show that proper band alignment can improve the directionality of charge carrier collection to benefit the photovoltaic performance.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center on Nanostructuring for Efficient Energy Conversion (CNEEC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1370664
DOE Contract Number:  
SC0001060
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 119; Journal Issue: 6; Related Information: CNEEC partners with Stanford University (lead); Carnegie Institution at Stanford; Technical University of Denmark
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; catalysis (heterogeneous), solar (fuels), photosynthesis (natural and artificial), bio-inspired, electrodes - solar, defects, charge transport, materials and chemistry by design, synthesis (novel materials)

Citation Formats

Santra, Pralay K., Palmstrom, Axel F., Tanskanen, Jukka T., Yang, Nuoya, and Bent, Stacey F. Improving Performance in Colloidal Quantum Dot Solar Cells by Tuning Band Alignment through Surface Dipole Moments. United States: N. p., 2015. Web. doi:10.1021/acs.jpcc.5b00341.
Santra, Pralay K., Palmstrom, Axel F., Tanskanen, Jukka T., Yang, Nuoya, & Bent, Stacey F. Improving Performance in Colloidal Quantum Dot Solar Cells by Tuning Band Alignment through Surface Dipole Moments. United States. doi:10.1021/acs.jpcc.5b00341.
Santra, Pralay K., Palmstrom, Axel F., Tanskanen, Jukka T., Yang, Nuoya, and Bent, Stacey F. Thu . "Improving Performance in Colloidal Quantum Dot Solar Cells by Tuning Band Alignment through Surface Dipole Moments". United States. doi:10.1021/acs.jpcc.5b00341.
@article{osti_1370664,
title = {Improving Performance in Colloidal Quantum Dot Solar Cells by Tuning Band Alignment through Surface Dipole Moments},
author = {Santra, Pralay K. and Palmstrom, Axel F. and Tanskanen, Jukka T. and Yang, Nuoya and Bent, Stacey F.},
abstractNote = {Colloidal quantum dots (CQDs) have received recent attention for low cost, solution processable, high efficiency solid-state photovoltaic devices due to the possibility of tailoring their optoelectronic properties by tuning size, composition, and surface chemistry. However, the device performance is limited by the diffusion length of charge carriers due to recombination. In this work, we show that band engineering of PbS QDs is achievable by changing the dipole moment of the passivating ligand molecules surrounding the QD. The valence band maximum and conduction band minimum of PbS QDs passivated with three different thiophenol ligands (4-nitrothiophenol, 4-fluorothiophenol, and 4-methylthiophenol) are determined by UV–visible absorption spectroscopy and photoelectron spectroscopy in air (PESA), and the experimental results are compared with DFT calculations. These band-engineered QDs have been used to fabricate heterojunction solar cells in both unidirectional and bidirectional configurations. The results show that proper band alignment can improve the directionality of charge carrier collection to benefit the photovoltaic performance.},
doi = {10.1021/acs.jpcc.5b00341},
journal = {Journal of Physical Chemistry. C},
number = 6,
volume = 119,
place = {United States},
year = {Thu Feb 12 00:00:00 EST 2015},
month = {Thu Feb 12 00:00:00 EST 2015}
}