Morphological Evolution and Its Impacts on Performance of Polymer Solar Cells

Devendra Khatiwada, Swaminathan Venkatesan, Jihua Chen, Qiliang Chen, Nirmal Adhikari, Ashish Dubey, Abu Farzan Mitul, Lal Mohammad, Jianyuan Sun, Cheng Zhang, Linbao Luo, Qiquan Qiao

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

In this paper, the role of fullerene loading on the nanomorphology and photovoltaic performance of alternating copolymer poly{2-octyldodecyloxy-benzo[1,2-b;3,4-b] dithiophene-alt-5,6-bis(dodecyloxy)-4,7bis(thiophen-2-yl)-benzo[c] [1,2,5]-thiadiazole} (PBDT-ABT-1) blend films was investigated. The morphology of blend films with different Phenyl C-60-butyric acid methyl ester (PCBM) mixing ratios and solvent additives was studied using atomic force microscopy (AFM) and energy-filtered transmission electron microscopy (EFTEM). AFM and EFTEM images showed difference in the intermixing of polymer with fullerene between 1:1, 1:2, and 1:3 weight ratios. Polymer/PCBM intermixed domain size increases with higher PCBM weight ratios. X-ray diffraction measurements on the pristine polymer and blend films cast without additives did not show any peaks, suggesting an amorphous nature of PBDT-ABT-1. EFTEM images from the donor/acceptor composite showed intermixed polymer-PCBM domains separated by the polymer boundary. Furthermore, EFTEM images for di-iodooctane (DIO) additive cast film revealed purer polymer domain. Photo-charge extraction by linearly increasing voltage measurement exhibited that charge extraction is highest in the nanomorphology sample with a weight ratio of 1:2, corresponding to the lowest bimolecular recombination and the highest charge carrier mobility.

Original languageEnglish (US)
Article number7060639
Pages (from-to)1284-1290
Number of pages7
JournalIEEE Transactions on Electron Devices
Volume62
Issue number4
DOIs
StatePublished - Apr 1 2015
Externally publishedYes

Keywords

  • Donor - acceptor ratio
  • morphology
  • polymer solar cell
  • solvent additive

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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