Rationalized Synthetic Access to Benzimidazoline Based N-Type Dopant

Molecular dopants have a fundamental role in tuning the electrical properties of organic semiconductors for a plethora of applications. Among these, 1H-Benzimidazoline-derivatives are particularly relevant for obtaining efficient n-doping of high electron affinity organic semiconductors. Structural modification of such compounds proved essential for tailoring their properties and doping performance according to the desired application. Versatile and efficient synthetic strategies, suitable to obtain a wide range of substitution motifs, are expected to improve access to known derivatives and allow the preparation of new and improved ones. However, due to a lack of rationalization and comprehensive analysis of literature-reported synthetic approaches, the selection of the best synthetic route for a specific target benzimidazoline derivative still mostly relies on a trial-and-error approach. In this contribution, we compare the two most popular synthetic strategies for the preparation of a wide library of benzimidazoline based n-type dopants having different substitution patterns. We thus propose guidelines for the selection of the best synthetic approach depending on the structure of the target product.