An investigation of the role acceptor side chains play in the processibility and efficiency of organic solar cells fabricated from small molecular donors featuring 3,4-ethylenedioxythiophene cores
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Organic photovoltaic devices fabricated from small molecular donors continue to receive significant interest due to their desirable properties such as convenient synthesis, purification and batch-to-batch reproducibility. In this study, we have synthesized two small molecules based on an alternating A-D-A structure, utilizing a central EDOT donor moiety and either 2-ethylhexyl cyanoacetate ( SAM-80 ) or N-(2-ethylhexyl)cyanoacetamide ( SAM-72 ) units as acceptor termini. The small molecules were incorporated into bulk heterojunction solar cells with PC71BM . Our investigations have shown that the side chains utilized for SAM-80 only allow for solution processing using volatile solvents, such as chloroform, which limits the reproducibility of device fabrication. However, SAM-72 displays better solubility and devices fabricated using a SAM-72:PC71BM active layer reached average power conversion efficiencies of 1.9%, with fill factors reaching 60%. Post-processing methods such as thermal and solvent vapor annealing were found to significantly increase the stability of devices, but were not able to improve overall device performance.
Mica , N , Almahmoud , S A J , Krishnan Jagadamma , L , Cooke , G & Samuel , I D W 2018 , ' An investigation of the role acceptor side chains play in the processibility and efficiency of organic solar cells fabricated from small molecular donors featuring 3,4-ethylenedioxythiophene cores ' , RSC Advances , vol. 8 , no. 69 , pp. 39231–39240 . https://doi.org/10.1039/C8RA07034B
Copyright 2018 the Authors. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/)
DescriptionThe authors are grateful for funding from EPSRC under grant codes EP/L012294/1, EP/L012170/1 and EP/L015110/1. Sondos Abdullah J Almahmoud acknowledges the Ministry of Higher education in Saudi Arabia for the funding and support.
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