Donor–Acceptor–Donor Modular Small Organic Molecul

Authors: Hemlata Patil Akhil Gupta Ante Bilic Sam Leslie Jackson Kay Latham Sheshanath V Bhosale

Publish Date: 2014/06/03

Volume: 43, Issue: 9, Pages: 3243-3254

PDF Link

Abstract

Two novel solutionprocessable small organic molecules 49bis4diphenylaminophenyl27dioctylbenzo38phenanthroline13682H7Htetraone S6 and 49bisbenzobthiophen2yl27dioctylbenzo38phenanthroline1368 2H7Htetraone S7 have been successfully designed synthesized characterized and applied in solutionprocessable photovoltaic devices S6 and S7 contain a common electronaccepting moiety naphthalene diimide NDI with different electrondonating moieties triphenylamine S6 and benzothiophene S7 and are based on a donor–acceptor–donor structure S7 was isolated as black rodshaped crystals Its triclinic structure was determined by single crystal xray diffraction XRD space group Pbar1 Z = 2 a = 94345 Å b = 144607 Å c = 153598 Å α = 672569 degrees β = 8035611 degrees γ = 7661810 degrees at 150 Kelvin K R = 0073 Ultraviolet–visible absorption spectra revealed that use of triphenylamine donor functionality with the NDI acceptor unit resulted in an enhanced intramolecular charge transfer ICT transition and reduction of the optical band gap compared with the benzothiophene analogue Solutionprocessable inverted bulk heterojunction devices with the structure indium tin oxide/zinc oxide 30 nm/active layer/molybdenum trioxide 10 nm/silver 100 nm were fabricated with S6 and S7 as donors and 66phenyl C70butyric acid methyl ester PC70BM as acceptor Power conversion efficiencies of 022 for S6/PC70BM and 010 for S7/PC70BM were achieved for the preliminary photovoltaic devices under simulated AM 15 illumination 100 mW cm−2 This paper reports donor–acceptor–donor modular small organic molecules with NDI as central accepting unit that have been screened for use in solutionprocessable inverted photovoltaic devicesHP acknowledges the assistance of Dr Jegadesan Subbiah from Bio21 Institute University of Melbourne VIC 3010 for providing support and guidance during the fabrication of OPV devices SVB acknowledges financial support from the Australian Research Council under a Future Fellowship Scheme FT110100152 and the School of Applied Sciences RMIT University for the facilities The CSIRO Materials Science and Engineering CMSE is acknowledged for providing support through a visiting fellow position AG AB thanks CSIRO for support through the Julius Career Award Use of the NCI National Facility supercomputers at the ANU is gratefully acknowledged

Keywords: