High Performance Organic Semiconductor for Organic Photovoltaics and Organic Field Effect Transistor Based on Ethynylene Tied Zinc Porphyrin and Benzothiadiazole-Thiophen Oligomers

Design and fabrication of high-performance organic semiconductors are still challenging. Here, we designed new D-(A)n type zinc porphyrin end-capped ethynylene-7-(4-hexyl-thiophen-2-yl)-2,1,3-benzothiadiazole (EBTT) oligomers by linking 5,10,15-trisphenyl porphyrin zinc (ZnTPP) with length-variable EBTT oligomers (at the 20-position of porphyrin) [ZnTPP(EBTT)n (n = 1–6)]. The influence of oligomer length on molecular structures, orbital energies, electronic absorption spectra, ionization energies, electronic affinities, and reorganization energies was systematically studied through density functional theory. The charge-carrier mobility of the simulated crystals and the power conversion efficiencies (PCE) using PCBM as the accepter were also predicted. ZnTPP(EBTT)6 show excellent hole/electron mobility of 76.161/9.395 cm2V−1s−1 and extremely high PCE of 25.45%. This work would have significance for the design and synthesis of organic semiconductor materials with large charge-carrier mobility and high PCE performance.