Oxygen Versus Water induced Degradation of an inverted Polymer Solar Cell

The relative effect of water and oxygen on the extent of degradation in an inverted polymer solar cell was studied. Carefully disassembling the devise revealed detailed information on where and to what extent degradation had occurred at different interfaces of the device. Chemical characterization was based on X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry in conjunction with isotopic labeling using 18-H2O and 18-O2.

A comparison was made between a water atmosphere and an oxygen atmosphere on devices that were kept in the dark and devices that had been subjected to illumination under simulated sunlight. The active material comprised a bulk heterojunction formed by poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester sandwiched between a layer of zinc oxide and a layer of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) that acted as barrier layers for the active material and the two electrodes indium tin oxide and silver.