Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 60: Organic Electronics and Photovoltaics: OPV II (jointly with CPP, HL)
TT 60.4: Talk
Wednesday, March 18, 2015, 10:15–10:30, C 130
The Effect of Solvent Additive on Generation, Recombination and Extraction in PTB7:PCBM Solar Cells: A conclusive Experimental and Numerical Simulation Study — •Juliane Kniepert1, Ilja Lange1, Thomas Brenner1, Jan Anton Koster2, and Dieter Neher1 — 1Universität Potsdam, Germany — 2University of Groningen, The Netherlands
Time delayed collection field (TDCF), bias amplified charge extraction (BACE) and space charge limited current (SCLC) measurements are combined with complete numerical device simulations to unveil the effect of the solvent additive 1,8-diiodooctane (DIO) on the performance of PTB7:PCBM bulk heterojunction solar cells. DIO is shown to increase the charge generation rate, reduce geminate and bimolecular recombination and increase the electron mobility. In total, the reduction of loss currents by processing with the additive raises the power conversion efficiency of the PTB7:PCBM blend by a factor of almost three. Our device simulations show unambiguously that the effect of the additive on the shape of the current-voltage curve cannot be ascribed to the variation of only the mobility, the recombination or the field-dependence of generation. It is only when the changes of all three parameters are taken into account that the simulation matches the experimental J-V-characteristics under all illumination conditions and for a wide range of voltages.