Synthesis, optical and electrochemical properties of the A-pi-D-pi-A porphyrin and its application as an electron donor in efficient solution processed bulk heterojunction solar cells

A conjugated acceptor-donor-acceptor (A-pi-D-pi-A) with the Zn-porphyrin core and the di-cyanovinyl substituted thiophene (A) connected at meso positions denoted as VC62 was designed and synthesized. The optical and electrochemical properties of VC62 were investigated. This new porphyrin exhibits a broad and intense absorption in the visible and near infrared regions. Bulk-heterojunction (BHJ) solution processed organic solar cells based on this porphyrin, as electron donor material, and PC71BM ([6,6]-phenyl C-71 butyric acid methyl ester), as electron acceptor material, were fabricated using THF and a pyridine-THF solvent exhibiting a power conversion efficiency of 3.65% and 5.24%, respectively. The difference in efficiencies is due to the enhancement of the short circuit current J(sc) and FF of the solar cell, which is ascribed to a stronger and broader incident photon to current efficiency (IPCE) response and a better balanced charge transport in the device processed with the pyridine-THF solvent.