PV RESEARCHOriginal Article Published by the U.S. Naval Research Laboratory
Does research on quantum dots matter in the plight for solar cell efficiency?
U.S. Naval Research Laboratory (NRL) research scientists and engineers in the Electronics Science and Technology Division have demonstrated the highest recorded open-circuit voltages for quantum dot solar cells to date. Using colloidal lead sulfide (PbS) nanocrystal quantum dot (QD) substances, researchers achieved an open-circuit voltage (VOC) of 692 millivolts (mV) using the QD bandgap of a 1.4 electron volt (eV) in QD solar cell under one-sun illumination.
"These results clearly demonstrate that there is a tremendous opportunity for improvement of open-circuit voltages greater than one volt by using smaller QDs in QD solar cells," said Woojun Yoon, Ph.D., NRC postdoctoral researcher, NRL Solid State Devices Branch. "Solution processability coupled with the potential for multiple exciton generation processes make nanocrystal quantum dots promising candidates for third generation low-cost and high-efficiency photovoltaics."
Despite this remarkable potential for high photo current generation, the achievable open-circuit voltage is fundamentally limited due to non-radiative recombination processes in QD solar cells. To overcome this boundary, NRL researchers have re-engineered molecular passivation in metal-QD Schottky junction (unidirectional metal to semiconductor junction) solar cells capable of achieving the highest open-circuit voltages ever reported for colloidal QD based solar cells.
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