With the addition of a dash of a common solvent, researchers realized an efficiency gain of about 36 percent for organic solar cells. A team led by Oak Ridge National Laboratory’s Kai Xiao added diiodooctane – 3 percent of the weight of the entire solution – to a blend of polymers and fullerene derivatives and saw the cell’s power conversion efficiency jump from 4.5 percent to 7.1 percent. An added benefit is that the technique requires no additional processing, which means lower costs and higher production efficiency. While similar efficiency gains have been documented, this work provides a glimpse into the phase-segregated domains of electron donors and acceptors as they approach the theoretical optimum size of 20 nanometers. These findings were presented in a recent paper published in Advanced Functional Materials.