Analysis of the injection layer of PTCDA in OLEDs using x-ray photoemission spectroscopy and atomic force microscopy

Through the investigation of the sample surface and interface of 3, 4, 9,10-perylenetetracarboxylic dianhydride (PTCDA)/indium-tin-oxide (ITO) thinfilms using atomicforce microscopy, it has been found that the surface is complanate, thegrowth is uniform and thedefects cover basically the surface of ITO. Furthermore, the number ofpinholes is small. Theanalysis of the sample surface and interface further verifies this result byusing x-rayphotoemission spectroscopy . At the same time, PTCDA is found to have the ability of restrainingthe diffusion of chemical constituents from ITO to the hole transport layer,which is beneficial tothe improvement of the performance and the useful lifetime of the organiclight emittingdiodes (OLEDs).