Effects of dynamic 3D-volume of side chains in conjugated polymers on nano-scale morphology and solar cell properties

Sungmin Park, Dongkyun Seo, Kyungwon Kwak, Dae Sung Chung, Cheol Hong Cheon, Bong Soo Kim, Hae Jung Son

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

We have synthesized a series of benzo[1,2-b:4,5-b′]-dithiophene (BDT)-co-thieno[3,4-b]thiophene (TT) based polymers with various alkyl side chains and bridging-atom on their TT units and studied the effects of the variation in the effective van der Waals volumes (eVol) of the side chains on the photovoltaic properties of the associated bulk heterojunction (BHJ) solar cells. eVol was found to be correlated with the degree of phase separation in the BHJ film, which affects the area of the polymer-PC71BM interface and the charge mobility. The polymer has a 2-ethylhexyl group that results in a relatively optimal BHJ film morphology, with sufficient polymer-PC71BM interfacial area for efficient charge generation and minimal charge mobility loss upon BHJ film formation. As a result, the solar cell device (2-ethylhexyl polymer) exhibits the highest power conversion efficiency of 8.25% because its short-circuit current density value (16.24 mA/cm2) and fill factor (0.674) are the highest of the synthesized polymers.

Original languageEnglish
Pages (from-to)323-330
Number of pages8
JournalDyes and Pigments
Volume123
DOIs
Publication statusPublished - 2015 Dec 1

Bibliographical note

Funding Information:
This work was supported by the Global Frontier R&D Program on Center for Multiscale Energy System funded by the National Research Foundation under the Ministry of Science, Korea Institute of Science and Technology (KIST) for Project No. 2E25392, and the New and Renewable Energy Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of Trade, Industry & Energy (MTIE) ( 20133030000130 , 20113030010030 ). K.K. expresses thanks for financial support from NRF Fund No. 2009-0093817 .

Publisher Copyright:
© 2015 Elsevier Ltd. All rights reserved.

Keywords

  • Charge mobility
  • Conjugated polymer
  • Effective van der Waals volume
  • Morphology
  • Polymer solar cells
  • Power conversion efficiency

ASJC Scopus subject areas

  • General Chemical Engineering
  • Process Chemistry and Technology

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