Thanks to the bulk-heterojunction (BHJ) feature of polymer solar cells (PSC), additional light active components can be added with ease to form ternary solar cells. This strategy has achieved great success largely to expand the spectral response range to improve power conversion efficiency (PCE) without incurring excessive processing costs. Here, we report ternary blend polymer-polymer solar cells comprised of PTB7, P3HT, and PC71BM with PCE as high as 8.2%. Analysis from femtosecond time resolved photoluminescence and transient absorption spectrometer confirm that P3HT is effective in transferring energy non-radiatively by inducing excitons and prolonging their overall lifetime in PTB7. Furthermore, solvent vapor annealing (SVA) treatment has been employed to improve the overly-coarse surface morphology. As a result, the fill factor and interfacial recombination has been further improved, boosting the PCE to 8.7%.