A Windmill-Shaped Molecule with Anthryl Blades to Form Smooth Hole-Transport Layers via a Photoprecursor Approach

Abstract

Preparation of high-performance organic semiconductor devices requires precise control over the active-layer structure. To this end, we are working on the controlled deposition of small-molecule semiconductors through a photoprecursor approach wherein a soluble precursor compound is processed into a thin-film form and then converted to a target semiconductor by light irradiation. This approach can be applied to layer-by-layer solution deposition, enabling the preparation of p–i–n-type photovoltaic active layers by wet processing. However, molecular design principles are yet to be established toward obtaining desirable thin-film morphology via this unconventional method. Herein, we evaluate a new windmill-shaped molecule with anthryl blades, 1,3,5-tris(5-(anthracen-2-yl)thiophen-2-yl)benzene, which is designed to deposit via the photoprecursor approach for use as the p-sublayer in p–i–n-type organic photovoltaic devices (OPVs). The new compound is superior to the corresponding precedent p-sublayer materials in terms of forming smooth and homogeneous films, thereby leading to improved performance of p–i–n OPVs. Overall, this work demonstrates the effectiveness of the windmill-type architecture in preparing high-quality semiconducting thin films through the photoprecursor approach.

Keywords

• organic photovoltaics
• morphology
• layer-by-layer solution process
• acenes