Journal
ADVANCED MATERIALS
Volume 30, Issue 9, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.201706124
Keywords
molecular packing; polymer solar cells; power conversion efficiencies; small molecular acceptors
Categories
Funding
- National Natural Science Foundation of China (NSFC) [21572171, 91633301]
- Innovative Research Group of Hubei Province [2015CFA014]
- DOE, Office of Science
- DOE, Office of Basic Energy Sciences
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A novel small molecule acceptor MeIC with a methylated end-capping group is developed. Compared to unmethylated counterparts (ITCPTC), MeIC exhibits a higher lowest unoccupied molecular orbital (LUMO) level value, tighter molecular packing, better crystallites quality, and stronger absorption in the range of 520-740 nm. The MeIC-based polymer solar cells (PSCs) with J71 as donor, achieve high power conversion efficiency (PCE), up to 12.54% with a short-circuit current (J(SC)) of 18.41 mA cm(-2), significantly higher than that of the device based on J71:ITCPTC (11.63% with a J(SC) of 17.52 mA cm(-2)). The higher J(SC) of the PSC based on J71:MeIC can be attributed to more balanced (h)/(e), higher charge dissociation and charge collection efficiency, better molecular packing, and more proper phase separation features as indicated by grazing incident X-ray diffraction and resonant soft X-ray scattering results. It is worth mentioning that the as-cast PSCs based on MeIC also yield a high PCE of 11.26%, which is among the highest value for the as-cast nonfullerene PSCs so far. Such a small modification that leads to so significant an improvement of the photovoltaic performance is a quite exciting finding, shining a light on the molecular design of the nonfullerene acceptors.
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