Panchromatic terthiophenyl-benzodithiophene conjugated porphyrin donor for efficient organic solar cells

Abstract

Two intermediate-sized acceptor–π–porphyrin–π–acceptor-type molecules MPor1 and MPor2 with panchromatic absorption profiles have been developed towards improving photovoltaic performance. The conjugation of terthiophenyl-benzodithiophene to the porphyrin center successfully fills the absorption gap between the Soret and Q bands of the conventional porphyrin molecules and leads to narrow optical bandgaps within 1.58–1.60 eV. The two molecules possess excellent light-harvesting property within the UV-visible-near-infrared region, and efficient hole-electron separation in the bulk heterojunction layer with PC₇₁BM as the acceptor. Conventional solar cells based on the MPor1/PC₇₁BM active layer shows an optimal performance with a power conversion efficiency of 8.59% and a short circle current of 14.91 mA cm⁻².