Since the past few years, porphyrin derivatives have attracted scientists' attention to be involved in the photon-to-charge conversion process in organic solar cells (OSCs). Here, we adopt a supramolecular assembly concept to produce a brand new derivate while preparaing donor-acceptor bulk heterojunction composite for the photoactive material of OSCs. The complexation of nitrogen lone pairs in the bidentate ligands to the axial orbitals of both zinc atoms in zinc-metalated porphyrin dimers (KC2s) forming a new porphyrin derivative, KC2-duplex. According to the UV-vis absorption spectrum, there is a red-shift of Q-band after assembly, indicating an improvement of intermolecular interaction. With this new mixture composed of KC2-duplex and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the photoactive material, the fabricated devices demonstrate a 38.7% enhancement of short circuit current density (Jsc), which is attributed to the improved hole mobility and exciton dissociation probability.