High Fill Factor Solution Processed Copper Phthacyloanine Nanoparticle Organic Solar Cells

Copper phthalocyanine (CuPc) organic solar cells (OSCs) have attracted more attentions because of the long-term stability, however, the high-cost fabrication method limits the application of CuPc OSCs. Here we report a surfactant-free CuPc nanoparticle organic solar cell with a much improved fill factor of 0.58, a power conversion efficiency (PCE) of 0.97% by low-cost spin coating process. Annealing plays a key role on the enhancement of the power conversion efficiency and the fill factor. The improvement of fill factor is attributed to the formation of nanoscale connection among CuPc nanoparticles by annealing, which is suggested by the decrease of series resistance and increase of parallel resistance. The formation of nanoscale connection is also confirmed by the size growth of the CuPc nanoparticles. We also discover that the electrical contact between the CuPc nanoparticle layer and hole transportation layer, and the electrical contact among CuPc nanoparticles are both improved by annealing.