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

Abstract 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 °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 × 10 ⁻² cm ² V ⁻¹ s ⁻¹ at an electric field of 1.0 × 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∼0.71 and power conversion efficiencies of 1.7∼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.