Charge transfer reactions in near IR absorbing small molecule solution processed organic bulk-heterojunction solar

We have measured the charge transfer processes on near IR small molecule solution processes solar cells under working conditions. The results show that there are two different behavior, for the device under working conditions, controlled by the intrinsic properties of the organic bulk-heterojunction phase to store charges at the different organic materials. Furthermore, our recombination kinetic studies show the origin of the photovoltage on these thin organic devices (80 nm thick) and the reason for the difference between the observed open circuit cell potential and the theoretical expected value based on the LUMOPCBM–HOMO phthalocyanine difference.

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► We prepared using solution processing methods near IR organic solar cells.
► Zn-phthalocyanine as electron donor and a fullerene derivate (PCBM) were employed.
► Different solvents induced huge changes on the photo-active layer nanomorphology.
► We evaluated the change recombination lifetime under device operating conductions.
► The device voltage depends on the accumulated charges and the charge recombination lifetime.