Chlorophylls (Chls), and associated chlorophyll derivatives, are one of the oldest, most versatile organic semiconductors found in nature. Herein, we present two easily semi-synthesized chlorophyll derivatives, namely, chlorin e6 trimethyl ester (Ce6Me3) and its copper complex (Cu–Ce6Me3), as the p-type dopants for organic semiconductors and their impact in organic solar cells (OSCs). In our study, both Chls showed intense Soret and Qy bands in the UV-visible spectra, leading to an effect means for capturing solar light and energy. Chls also exhibited high carrier mobility owing to the partial formation of aggregates through the spin-coating process. Using Chls, we fabricated OSCs in both planar-heterojunction (PHJ) and bulk-heterojunction (BHJ) solar cell configurations, together with C70/PC70BM as electron acceptors. In PHJ solar cells, we received solar power conversion efficiencies (PCEs) of only 0.85% and 0.93% for Cu–Ce6Me3- and Ce6Me3-based devices, respectively, with the thickness of the donor layer at 5 nm. In BHJ cells, we achieved much higher PCEs of 1.53% and 2.05% for Cu–Ce6Me3:PC70BM and Ce6Me3:PC70BM respectively, where both blending ratios were set to 1:8. The improvement on PCE in BHJ cells may be attributed to the better charge separation increase at the donor–acceptor interface.