Three new tailor-made molecules (DPDCTB, DPDCPB, and DTDCPB) were strategically designed and convergently synthesized as donor materials for small-molecule organic solar cells. These compounds possess a donor-acceptor-acceptor molecular architecture, in which various electron-donating moieties are connected to an electron-withdrawing dicyanovinylene moiety through another electron-accepting 2,1,3-benzothiadiazole block. The molecular structures and crystal packings of DTDCPB and the previously reported DTDCTB were characterized by single crystal X-ray crystallography. Photophysical and electrochemical properties as, well as energy levels of this series of donor molecules were thoroughly investigated, affording clear structure property relationships. By delicate manipulation of the trade-off between the photovoltage and the photocurrent via molecular structure engineering together with device optimizations, which included fine-tuning the layer thicknesses and the donor acceptor blended ratio in the bulk heterojunction layer, vacuum deposited hybrid planar mixed heterojunction devices utilizing DTDCPB as the donor and C-70 as the acceptor showed the best performance with a power conversion efficiency (PCE) of 6.6 +/- 0.2% (the highest PCE of 6.8%), along with an open circuit voltage (V-oc) of 0.93 +/- 0.02 V, a short-circuit current density (J(sc)) of 13.48 +/- 0.27 inA/cm(2), and a fill factor (FF) of 0.53 +/- 0.02, under 1 sun (100 mW/cm(2)) AM 1.5G simulated solar illumination.