January 8, 2015
      
                  
        
  Author(s)
  Lee J. Richter,   Regis J. Kline,   Hyun Wook  Ro,   Chad R. Snyder,   Andrew A. Herzing,   Sebastian  Engmann
 
       
            
    
    
        A consensus is emerging that every phase present in a bulk heterojunction organic photovoltaic (OPV) device is not material pure. In general, there will exist at least one region characterized by a mixture of donor and acceptor. Significant insights into