We report the Cu + chelated poly-alkoxythiophene (P3MEET) enhancement of a solar cell device consisting of a P3HT/PCBM heterojunction system. Compared to the reference P3HT/PCBM system, a consistent increase of conversion efficiency of 0.9% via an apparent increase of incident-photon-to-current conversion efficiency (IPCE) is achieved upon optimizing the ratio of P3MEET-Cu + : P3HT : PCBM to 1 : 9 : 6 by weight, in which 7.5 mol% of CuBr is added upon synthesizing P3MEET-Cu + . The results, in combination with relevant data gathered from atomic force microscopy, cyclic voltammetry, and electrochemical impedance spectra, lead us to conclude that the match in redox potential and increase of ordering of the film upon doping P3MEET-Cu + play two key roles in enhancing the performance.