Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 45: Organic electronics and photovoltaics: OPV II (CPP with HL/TT)
HL 45.5: Talk
Wednesday, March 18, 2015, 10:30–10:45, C 130
Quantification of loss channels in bulk heterojunction organic solar cells based on DPP-type donor-acceptor copolymers blended with PC71BM — •Julian Robert Ochsmann1, Deepak Chandran2,3, Kwang-Sup Lee3, and Frédéric Laquai1 — 1Max Planck Institute for Polymer Research, Mainz, Germany — 2Dublin City University, Dublin, Ireland — 3Hannam University, Daejeon, South Korea
A promising approach to improve the performance of bulk-heterojunction (BHJ) organic solar cells (OSC) is to use low-bandgap polymers as electron donor materials as they enhance the photon absorption of the photoactive layer in the near infrared wavelength range and thereby increase the photocurrent. In addition, low-bandgap polymers are suitable for use in tandem solar cells, since their absorption spectrum is complementary to that of mid-bandgap polymers such as P3HT or PCDTBT, which allows for photocurrent matching of front and back cells. A promising class of low-bandgap polymers for single- and multijunction solar cells are donor-acceptor type copolymers based on diketopyrrolopyrrole (DPP) units. In this study we investigate the photovoltaic performance and the photophysics of two DPP-based copolymers, namely PTDPP-TT and PFDPP-TT, blended with PC71BM and applied in single junction BHJ solar cells. The photophysics of the OSC devices were investigated with broadband transient absorption pump-probe spectroscopy (TA) and analyzed with a previously reported model of charge recombination that allows to quantify the loss channels in devices.