High-Performance Organic Photovoltaic Devices Using a New Amorphous Molecular Material with High Hole Drift Mobility, Tris[4-(5-phenylthiophen-2-yl)phenyl]amine

A new amorphous molecular material, tris[4-(5-phenylthiophen-2-yl)phenyl]amine (TPTPA), is synthesized and characterized. TPTPA forms a stable amorphous glass with a glass-transition temperature of 83 degrees C when the melt sample is cooled. It also forms amorphous thin films by a thermal deposition technique. TPTPA exhibits a hole drift mobility of 1.0 x 10(-2) cm(2) V-1 s(-1) at an electric field of 1.0 x 10(5) V cm(-1) and at 293 K, as determined by the time-of-flight method, which is of the highest level among those of amorphous molecular materials. pn-Heterojunction organic photovoltaic devices (OPVs) using TPTPA as an electron donor and C-60 or C-70 as an electron acceptor exhibit high performance with fill factors of 0.66 similar to 0.71 and power conversion efficiencies of 1.7 similar to 2.2% under air-mass (AM) 1.5G illumination at an intensity of 100 mW cm(-2), which are of the highest level ever reported for OPVs using amorphous molecular materials.