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Homocoupling Defects of a Small Donor Molecule for Organic Photovoltaics: Quantification of the Eutectic State Diagram by Rapid Heat–Cool Differential Scanning Calorimetry
The conjugated small donor molecule p-DTS(FBTTh2)2, leading to efficient bulk heterojunction organic photovoltaic devices with PC71BM, shows a eutectic phase behavior in combination with its homocoupled analogue. Rapid heat–cool differential scanning calorimetry allows us to construct the state dia...
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Published in: | Journal of physical chemistry. C 2019-09, Vol.123 (36), p.22634-22642 |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The conjugated small donor molecule p-DTS(FBTTh2)2, leading to efficient bulk heterojunction organic photovoltaic devices with PC71BM, shows a eutectic phase behavior in combination with its homocoupled analogue. Rapid heat–cool differential scanning calorimetry allows us to construct the state diagram based on (i) the endset of melting of p-DTS(FBTTh2)2:homocoupled p-DTS(FBTTh2)2 mixtures of different compositions, and (ii) partial integration of the melting trajectory of these mixtures by calculating the fraction of the molten pure excess phase as a function of temperature. These quantitative experimental results are supported by a theoretical calculation model based on Schröder-van Laar equations extended with an interaction function representing the interactions between the mixture’s components in the liquid state. The eutectic composition around 30 wt % of homocoupled p-DTS(FBTTh2)2 shows the lowest crystallinity (order) of all mixtures together with a maximum loss of photovoltaic efficiency. |
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ISSN: | 1932-7447 1932-7455 |
DOI: | 10.1021/acs.jpcc.9b06336 |