Although NiO exhibits great potential as a hole transport layer in polymer organic electronic devices, our understanding of the atomic structure of organics/NiO interfaces and the effect of NiO surface modification on device performance is still limited. Here, we report the study of the structure and electronic properties of the monomer of the regioregular poly(3-hexylthiophene) (rr-P3HT)/NiO (100) interface by means of first-principles calculations. Different adsorption sites and orientations were studied, and a global minimum configuration was determined. The backbone of P3HT monomer prefers to orient along the O-O direction, while the side chains prefer to align in the Ni-O direction of the NiO (100) surface. Although a significant contribution to the adsorption energy comes from the side chains, strong electronic coupling is found between the backbone of P3HT and NiO. Our calculations indicate that the interfacial electronic structure of organics/NiO is key to device performance. Further, the calculated interfacial electronic structures demonstrate the critical role of oxygen in enhancing hole transport and electron blocking between P3HT and NiO and provide a possible explanation for the increased performance in O2-plasma-treated NiO devices observed in experiments.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films