N,N-Di aryl anilinosquaraines and Their Application to Organic Photovoltaics
Diev, Vyacheslav V.
Djurovich, Peter I.
Forrest, Stephen R.
Thompson, Mark E.
KAUST Grant NumberKUS-C1-015-21
MetadataShow full item record
AbstractWe report new derivatives of symmetric squaraine dyes with N,N-diarylanilino substituents that have high solubility and high absorptivity (ε = 0.71-4.1 ×105 M-1cm-1) in the red solar spectral region (λmax = 645-694 nm) making them promising candidates for application in organic photovoltaics (OPVs). Unsymmetrical N,N-diisobutylanilino- and N,N-diphenylanilino(diphenylamino) squaraines have also been prepared that give blue-shifted absorption spectra (λmax = 529-535 nm) relative to their symmetric counterparts. Compared to bis(N,N-diisobutylanilino)squaraine, both symmetrical and unsymmetrical N,N-diarylanilino squaraines show markedly broader absorption bands in solution than their N,N-dialkylanilino squaraine counterparts: the full width at half-maximum (fwhm) for N,N-diarylanilino squaraines range from 1280-1980 cm-1, while the fwhm value for the N,N-diisobutylanilino squarine is only 630 cm-1. The absorption bands for thin films of N,N-diarylanilino squaraines broaden further to 2500-3300 cm-1. N,N-Diarylanilino squaraines are fluorescent, albeit with lower quantum yields than bis(N,N-diisobutylanilino)squaraine (φPL = 0.02-0.66 and 0.80, respectively). OPVs were prepared with solution processed squaraine layers using the following structure: ITO/squaraine (66-85 Å)/C60 (400 Å)/BCP (100 Å)/Al (1000 Å), BCP = bathocuproine. Devices using thin films of the bis(N,N-diarylanilino)squaraines as donor layers show improved performance relative to OPVs prepared with bis(N,N-dialkylanilino) squaraines, i.e. bis(N,N-diisobutylanilino)squaraine: open-circuit voltage Voc = 0.59 ± 0.05 V, short-circuit current Jsc = 5.58 ± 0.16 mA/cm2, fill factor FF = 0.56 ± 0.03, and power conversion efficiency η = 1.8 ± 0.2% under 1 sun, AM1.5G simulated illumination, compared with bis(N,N-diphenylanilino)squaraine: V oc = 0.82 ± 0.02 V, Jsc = 6.71 ± 0.10 mA/cm2, FF = 0.59 ± 0.01, and η = 3.2 ± 0.1%. Morphological studies of thin films suggest that the solubility of bis(N,N-diarylanilino)squaraines plays an important role in controlling the optoelectronic properties of the OPVs. © 2011 American Chemical Society.
CitationWang S, Hall L, Diev VV, Haiges R, Wei G, et al. (2011) N,N-Di aryl anilinosquaraines and Their Application to Organic Photovoltaics . Chem Mater 23: 4789–4798. Available: http://dx.doi.org/10.1021/cm2020803.
SponsorsFunding for this research was provided by the Center for Advanced Molecular Photovoltaics (CAMP) (award KUS-C1-015-21) of the King Abdullah University of Science and Technology (KAUST), the US Department of Energy Frontier Center at the University of Southern California (award DE-SC0001011, S.W. and M.E.T.), the US Department of Energy EERE Beyond the Horizon program (DE-FG36-08GO18022, G. W. and S.R.F.), and the Global Photonic Corporation. We also like to thank Dr. Frederico A. Rabuffetti for assistance with the TGA measurements.
PublisherAmerican Chemical Society (ACS)
JournalChemistry of Materials