Improved Optical Field Distribution and Charge Extraction through an Interlayer of Carbon Nanospheres in Polymer Solar Cells

Nanostructured carbon is a low-cost, economic, and elementally abundant candidate for manufacturing high-conductivity counter electrodes of organic photoelectric devices. Herein, we prepare onion-like carbon nanosphere:silver (OLCNS:Ag) composite electrodes for efficient, inverted-architecture polymer solar cells (PSCs) via a simple, solution-processed approach. The optical electric field distribution from the OLCNS:Ag nanocomposite layer opens up the possibility of additional light harvesting of the entire visible spectrum resulting from synergies between both components. The large effective specific surface area and high conductivity of OLCNS allow significant charge transfer and collection, resulting in a remarkably enhanced power conversion efficiency (PCE) of 9.81% in PTB7:PC71BM PSCs and 6.95% in PCDTBT:PC71BM PSCs, compared with control devices with PCEs of 7.76 and 5.31%, respectively. These consequences indicate that OLCNS:Ag composite electrodes constitute a valid and versatile method for realiz...