Abstract
Fullerene-free all-small-molecule organic photovoltaic cells (SM-OPVs) have attracted considerable attention because of well-defined molecular structures with low batch-to-batch variation. Porphyrin derivatives have recently emerged as one of the promising conjugated building blocks for the small-molecule (SM) donors. Herein, we first report fullerene-free SM-OPVs employing porphyrin-based donors. Three zinc porphyrin (PZn)-based SM donors, which have strong bimodal absorption in the visible region and near-infrared region, are synthesized. Constructing bulk-heterojunction (BHJ) active layers using the PZn donors and a SM acceptor, IDIC, which have complementary absorption, achieved panchromatic photon-to-current-conversion from 400 to 900 nm. The manipulation of side chains in the PZn donors considerably influenced the molecular ordering and nanomorphology of the BHJ active layers. PZn-based fullerene-free SM-OPV devices with promising power conversion efficiency of 6.13% were achieved, which also offers crucial guidance for developing fullerene-free OPVs using porphyrin derivatives.