Photo-degradation of the indium tin oxide (ITO)/organic interface in organic optoelectronic devices and a new outlook on the role of ITO surface treatments and interfacial layers in improving device stability

This work focuses on the effect of light exposure on ITO/organic interface in organic optoelectronic devices, including organic light emitting devices (OLEDs), organic photo-detectors (OPDs) and organic solar cells (OSCs). The results show that irradiation by light in the visible and UV range leads to a gradual deterioration in charge injection and extraction across the interface. A correlation between the performance stability of the devices and the photo-stability of the ITO/organic contacts is established. Studies also show that this photo-induced degradation can be significantly reduced by means of ITO surface treatment or through the insertion of interfacial layers between ITO and the organic layers. X-ray Photoelectron Spectroscopy (XPS) measurements reveal detectable changes in the interface characteristics after irradiation, indicating that the photo-degradation of the ITO/organic contacts is chemical in nature. Changes in XPS characteristics after irradiation suggest a possible reduction in bonds between ITO and its adjacent organic layer. The results shed light on a new material degradation mechanism that appears to have a wide presence in ITO/organic contacts in general, and which may play a key role in limiting the stability of various organic optoelectronic devices such as OLEDs, OSCs and OPDs.

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► The widely used ITO/organic interface suffers poor photo-stability.
► ITO surface treatment and insertion of interfacial layers significantly reduce the photo-degradation.
► XPS measurements reveal the photo-degradation is chemical in nature.