Star-shaped hole transport materials with indeno[1,2-b] thiophene or fluorene on a triazine core for efficient perovskite solar cells

New star-shaped hole transport materials including a 1,3,5-triazine core have been successfully synthesized and investigated for high performance perovskite solar cells. A maximum power conversion efficiency of 13.2% has been achieved by employing 2,2′,2′′-(1,3,5-triazine-2,4,6-triyl)tris(N,N-bis(4-methoxyphenyl)-4,4-dimethyl-4H-indeno[1,2-b]thiophen-6-amine). The power conversion efficiencies of hole transport materials were comparable to that of the standard spiro-OMeTAD (13.8%).