Hole-Transporting Spirothioxanthene Derivatives as Donor Materials for Efficient Small-Molecule-Based Organic Photovoltaic Devices

A new class of hole-transporting spirothioxanthene derivatives has been synthesized and characterized. Their photophysical, electrochemical and thermal properties have been studied. These compounds exhibit high hole mobilities of up to 1 × 10–3 cm2 V–1 s–1, determined by using thin film transistor technique. In addition, these spirothioxanthene derivatives are promising donor materials in the construction of high performance organic photovoltaic (OPV) devices. With a very low dopant concentration of 7%, highly efficient small molecule-based OPV devices with high short-circuit current density of 10.83 mA cm–2, open-circuit voltage of 0.94 V, and high power conversion efficiency of 5.40% (the highest PCE of 5.46%) have been realized.