A new class of three-dimensional, p-type, spirobifluorene-modified perylene diimide derivatives for small molecular-based bulk heterojunction organic photovoltaic devices

A new class of non-planar and three-dimensional spirobifluorene-modified perylene diimide compounds has been successfully designed and synthesized. The functionalization of the perylene diimide core with different spirobifluorene moieties can alter the molecular geometry as well as extend the spectral coverage into the red region. In addition, these compounds can be utilized as donor materials in combination with fullerene to form bulk heterojunctions, and particularly efficient organic photovoltaic (OPV) devices demonstrating high open-circuit voltages of 0.97 V and a power conversion efficiencies of up to 4% have been prepared. These values are the highest among the cells utilizing p-type perylene diimide as photoactive material in OPV devices. This work opens up a new avenue for the design and synthesis of a new class of p-type perylene diimide compounds that are promising candidates as donor materials in the fabrication of OPV devices.