Enhancement of organic solar cell efficiency by altering the zinc oxide photoanode nanostructure morphology

Abstract

The current paper examines the effects of zinc oxide nanostructure configurations, as photoanode formations of organic solar cells, on the performance of power conversion. To this end, some experiments were conducted during which a near band edge emission red shift of ~0.11 eV from nanoparticles to vertically-oriented nanorods was observed. This bandgap narrowing promotes transferring of photo-excited electrons towards the conduction band of photoanode. A ~48% decrease in the deep level emission intensity revealed a smaller nonradiative waves emission due to lower level of crystal disorder. By using vertically-oriented zinc oxide nanorods as photoanodes, the photovoltaic efficiency of the organic solar cell improved considerably. The nanorod-structured photoanodes showed a 0.22 V rise in the open-circuit voltage, from 0.76 V to 0.98 V, and a 2.08 times increment in the overall conversion performance, compared to the zinc oxide nanoparticle-structured photoanodes. This superior performance is attributed to a greater chance of charge recombination and light-trapping in the cells, more efficient light absorption, and high level of crystallinity that grants easier electron mobility for vertically-oriented zinc oxide nanorods. Moreover, a smaller electron transfer impedance (0.85 ) was achieved due to better electrocatalytic action for oxygen reduction for vertical nanorods compared to the other two zinc oxide configurations (1.62  and 5.06 ). This boosted the cell performance by increasing the short-circuit current density (JSC). The fabricated solar cell may contribute to sustainable and environmentally-friendly electricity generation process through reducing the consumption of nonrenewable energy sources.

UV–Vis–NIR Broadband Self-Powered CuInS2/SnO2 Photodetectors and the Application in Encrypted Optical Communication

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