Roughening Conjugated Polymer Surface for Enhancing the Charge Collection Efficiency of Sequentially Deposited Polymer/Fullerene Photovoltaics
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Department of Chemistry and Nano Science, Ewha Womans University, Seoul 127-750, Korea
2
Graduate School of Energy, Environment, Water, and Sustainability (EEWS), Graphene Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
*
Author to whom correspondence should be addressed.
Academic Editors: Christian B. Nielsen and Laure Biniek
Polymers 2015, 7(8), 1497-1509; https://doi.org/10.3390/polym7081466
Received: 25 May 2015 / Revised: 21 July 2015 / Accepted: 6 August 2015 / Published: 13 August 2015
(This article belongs to the Special Issue Organic Photovoltaics)
A method that enables the formation of a rough nano-scale surface for conjugated polymers is developed through the utilization of a polymer chain ordering agent (OA). 1-Chloronaphthalene (1-CN) is used as the OA for the poly(3-hexylthiophene-2,5-diyl) (P3HT) layer. The addition of 1-CN to the P3HT solution improves the chain ordering of the P3HT during the film formation process and increases the surface roughness of the P3HT film compared to the film prepared without 1-CN. The roughened surface of the P3HT film is utilized to construct a P3HT/fullerene bilayer organic photovoltaic (OPV) by sequential solution deposition (SqSD) without thermal annealing process. The power conversion efficiency (PCE) of the SqSD-processed OPV utilizing roughened P3HT layer is 25% higher than that utilizing a plain P3HT layer. It is revealed that the roughened surface of the P3HT increases the heterojunction area at the P3HT/fullerene interface and this resulted in improved internal charge collection efficiency, as well as light absorption efficiency. This method proposes a novel way to improve the PCE of the SqSD-processed OPV, which can be applied for OPV utilizing low band gap polymers. In addition, this method allows for the reassessment of polymers, which have shown insufficient performance in the BSD process.
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Keywords:
organic photovoltaics; bilayer organic photovoltaics; sequential deposition; ordering agent
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MDPI and ACS Style
Jang, Y.; Seo, J.-W.; Seok, J.; Lee, J.-Y.; Kim, K. Roughening Conjugated Polymer Surface for Enhancing the Charge Collection Efficiency of Sequentially Deposited Polymer/Fullerene Photovoltaics. Polymers 2015, 7, 1497-1509.
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