Surface engineering of transparent conductive oxide (TCO) electrode using molecular termination layers

Novel axially substituted phthalocyanine (Pc) absorber molecules are synthesized and applied as monolayer termination on indium-tin-oxide (ITO) substrates used as front electrode in ZnPc/C60 organic solar cells. The presence of the chemisorbed molecules on the ITO surface is proven through near edge X-ray fine structure and X-ray photoelectron spectroscopy. The substrates work function increased from 4.3 to 5.0 eV close to the ZnPc highest occupied molecular orbital. s made on thus terminated ITO substrates show improved cell parameters. The new concept of absorber molecules with polar linkers as termination forms a band aligned π–π interface at the front contact raising the power conversion efficiency by 67% up to η = 2%.