Solution-processed
organic photovoltaics (OPVs) based on bulk-heterojunctions
have gained significant attention to alleviate the increasing demend
of fossil fuel in the past two decades. OPVs combined of a wide bandgap
polymer donor and a narrow bandgap nonfullerene acceptor show potential
to achieve high performance. However, there are still two reasons
to limit the OPVs performance. One, although this combination can
expand from the ultraviolet to the near-infrared region, the overall
external quantum efficiency of the device suffers low values. The
other one is the low open-circuit voltage (V
OC) of devices resulting from the relatively downshifted lowest
unoccupied molecular orbital (LUMO) of the narrow bandgap. Herein,
the approach to select and incorporate a versatile third component
into the active layer is reported. A third component with a bandgap
larger than that of the acceptor, and absorption spectra and LUMO
levels lying within that of the donor and acceptor, is demonstrated
to be effective to conquer these issues. As a result, the power conversion
efficiencies (PCEs) are enhanced by the elevated short-circuit current
and V
OC; the champion PCEs are 11.1% and
13.1% for PTB7-Th:IEICO-4F based and PBDB-T:Y1 based solar cells,
respectively.
Fullerene-passivated SnO2 electron transport layers (ETLs) offer the route for continued boost in power conversion efficiencies (PCEs) of perovskite solar cells (PSCs). However, the detailed understanding on the photocarrier dynamics...
This study presents synthesized small-molecule acceptors having the structure A-D-A´-D-A—where A, A´, and D represent the end group, the core and π-bridge unit, respectively—that form the active layers with the...
Ink-printing method emerges as a viable way for manufacturing large-scale flexible Cu(In,Ga)Se (CIGS) thin film photovoltaic (TFPV) devices owing to its potential for the rapid process, mass production, and low-cost nonvacuum device fabrication. Here, we brought the femtosecond laser annealing (fs-LA) process into the ink-printing CIGS thin film preparation. The effects of fs-LA treatment on the structural and optoelectronic properties of the ink-printing CIGS thin films were systematically investigated. It was observed that, while the film surface morphology remained essentially unchanged under superheating, the quality of crystallinity was significantly enhanced after the fs-LA treatment. Moreover, a better stoichiometric composition was achieved with an optimized laser scanning rate of the laser beam, presumably due to the much reduced indium segregation phenomena, which is believed to be beneficial in decreasing the defect states of In, V, and In. Consequently, the shunt leakage current and recombination centers were both greatly decreased, resulting in a near 20% enhancement in photovoltaic conversion efficiency.
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