Synthetic Conditions for High-Accuracy Size Control of PbS Quantum Dots.
Decreasing the variability in quantum dot (QD) syntheses is desirable for better uniformity of samples for use in QD-based studies and applications. Here we report a highly reproducible linear relationship between the concentration of ligand (in this case oleic acid, OA) and the lowest energy exciton peak position (nm) of the resulting PbS QDs for various hot-injection temperatures. Thus, for a given injection temperature, the size of the PbS QD product is purely controlled by the amount of OA. We used this relationship to study PbS QD solar cells that are fabricated from the same size of PbS QDs but synthesized using four different injection temperatures: 95, 120, 150, and 185 °C. We find that the power conversion efficiency does not depend on injection temperature but that the V(oc) is higher for QDs synthesized at lower temperatures while the J(sc) is improved in higher temperature QDs.
†School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, China.|‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.
Jianbing
J
Zhang
‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.|§Department of Physics, Colorado School of Mines, 1523 Illinois Street, Golden, Colorado 80401, United States.
Ryan W
RW
Crisp
‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.|∥Center for Advanced Solar Photophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
Jianbo
J
Gao
‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.|⊥Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States.
Daniel M
DM
Kroupa
‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.
Matthew C
MC
Beard
‡Chemical and Material Sciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States.
Joseph M
JM
Luther
ligands; nanocrystals; oleic acid; photovoltaics; solar cells