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This content will become publicly available on February 27, 2019

Title: Photobleaching dynamics in small molecule vs.  polymer organic photovoltaic blends with 1,7-bis-trifluoromethylfullerene

Two organic photovoltaic (OPV) donor materials (one polymer and one small molecule) are synthesized from the same constituent building blocks, namely thiophene units, cyclopentathiophene dione (CTD), and cyclopentadithiophene (CPDT). Photobleaching dynamics of these donor materials are then studied under white light illumination in air with blends of PC 70BM and the bistrifluoromethylfullerene 1,7-C 60(CF 3) 2. For both the polymer and small molecule blends, C 60(CF 3) 2 stabilizes the initial rate of photobleaching by a factor of 15 relative to PC70BM. However, once the small molecule:C 60(CF 3) 2 blend bleaches to ~80% of its initial optical density, the rate of photobleaching dramatically accelerates, which is not observed in the analagous polymer blend. We probe that phenomenon using time-resovled photoluminescence (TRPL) to measure PL quenching efficiencies at defined intervals during the photobleaching experiments. The data indicates the small molecule donor and C 60(CF 3) 2 acceptor significantly de-mix with time, after which the blend begins to bleach at approximately the same rate as the neat donor sample. The work suggests that perfluoroalkylfullerenes have great potential to stabilize certain OPV active layers toward photodegradation, provided their morphology is stable.
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  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Indian Inst. of Science, Bangalore (India)
  3. Colorado State Univ., Fort Collins, CO (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2050-7488; JMCAET; TRN: US1801925
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. A
Additional Journal Information:
Journal Volume: 6; Journal Issue: 11; Journal ID: ISSN 2050-7488
Royal Society of Chemistry
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
Country of Publication:
United States
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; organic photovoltaics; donor materials; OPV
OSTI Identifier: