Interface Electronic States of Epitaxially Grown C₆₀ on Dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene Single Crystals

Abstract

Electronic states formed at the interfaces of molecular semiconductor materials in organic optoelectronic devices are essential for their functionality. However, resolving these states at the complex and disordered interfaces of practical devices is challenging. In this study, the electronic states at well-defined molecular semiconductor p–n heterojunctions formed by epitaxial growth of C₆₀ on single-crystals of dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) were characterized by X-ray photoelectron spectroscopy and photoelectron yield spectroscopy. Our observations revealed the formation of interfacial electronic states and band bending on both sides of the heterojunction, suggesting electron transfer from DNTT to C₆₀. Notably, these features were not revolved for conventional disordered interfaces formed on vacuum-deposited thin-films of DNTT.