A Simple And Low-Cost Surface Treatment To Facilitate Charge Extraction And Eliminate Light Soaking Of Polymer Solar Cells

Recently, polymer solar cells (PSCs) based on low bandgap thienothiophene-benzodithiophene copolymer have exhibited rapidly raised efficiency, but light soaking phenomena has caused a great impact on device performance. Herein, Al3+ was introduced between indium tin oxides (ITO) electrode and poly[(9,9-bis(3 '-(N,Ndimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) electron extraction layer of PSCs. The incorporated Al3+ could not only effectively fill the defects on the surface of ITO, but also decrease electron transport barrier, which facilitates charge transfer and increases the dissociation of photogenerated excitons. As a consequence, the optimal buffer layer improves the photoconductivity response and suppresses the photocurrent hysteresis phenomena.