TY - JOUR
T1 - Highly Efficient Copper-Indium-Selenide Quantum Dot Solar Cells
T2 - Suppression of Carrier Recombination by Controlled ZnS Overlayers
AU - Kim, Jae Yup
AU - Yang, Jiwoong
AU - Yu, Jung Ho
AU - Baek, Woonhyuk
AU - Lee, Chul-Ho
AU - Son, Hae Jung
AU - Hyeon, Taeghwan
AU - Ko, Min Jae
PY - 2015/11/24
Y1 - 2015/11/24
N2 - Copper-indium-selenide (CISe) quantum dots (QDs) are a promising alternative to the toxic cadmium- and lead-chalcogenide QDs generally used in photovoltaics due to their low toxicity, narrow band gap, and high absorption coefficient. Here, we demonstrate that the photovoltaic performance of CISe QD-sensitized solar cells (QDSCs) can be greatly enhanced simply by optimizing the thickness of ZnS overlayers on the QD-sensitized TiO2 electrodes. By roughly doubling the thickness of the overlayers compared to the conventional one, conversion efficiency is enhanced by about 40%. Impedance studies reveal that the thick ZnS overlayers do not affect the energetic characteristics of the photoanode, yet enhance the kinetic characteristics, leading to more efficient photovoltaic performance. In particular, both interfacial electron recombination with the electrolyte and nonradiative recombination associated with QDs are significantly reduced. As a result, our best cell yields a conversion efficiency of 8.10% under standard solar illumination, a record high for heavy metal-free QD solar cells to date.
AB - Copper-indium-selenide (CISe) quantum dots (QDs) are a promising alternative to the toxic cadmium- and lead-chalcogenide QDs generally used in photovoltaics due to their low toxicity, narrow band gap, and high absorption coefficient. Here, we demonstrate that the photovoltaic performance of CISe QD-sensitized solar cells (QDSCs) can be greatly enhanced simply by optimizing the thickness of ZnS overlayers on the QD-sensitized TiO2 electrodes. By roughly doubling the thickness of the overlayers compared to the conventional one, conversion efficiency is enhanced by about 40%. Impedance studies reveal that the thick ZnS overlayers do not affect the energetic characteristics of the photoanode, yet enhance the kinetic characteristics, leading to more efficient photovoltaic performance. In particular, both interfacial electron recombination with the electrolyte and nonradiative recombination associated with QDs are significantly reduced. As a result, our best cell yields a conversion efficiency of 8.10% under standard solar illumination, a record high for heavy metal-free QD solar cells to date.
KW - copper-indium-selenide
KW - heavy metal-free
KW - quantum dot-sensitized solar cells
KW - recombination control
KW - ZnS overlayers
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U2 - 10.1021/acsnano.5b04917
DO - 10.1021/acsnano.5b04917
M3 - Article
AN - SCOPUS:84948406237
VL - 9
SP - 11286
EP - 11295
JO - ACS Nano
JF - ACS Nano
SN - 1936-0851
IS - 11
ER -