Effect of Thermal Annealing on Charge Transfer States and Charge Trapping in PCDTBT:PC₇₀BM Solar Cells

Abstract

The impact of thermal annealing on charge transfer (CT) states in poly[N-9″-hepta-decanyl-2,7-carbazole- alt -5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT):[6,6]-phenyl C71 butyric acid methyl ester (PC70BM) bulk heterojunction solar cells is analyzed. Thermal annealing is found to increase the effectiveness of the CT states, facilitating exciton dissociation and carrier generation. An increase in the concentration of deep traps due to annealing is presented using mid-gap photothermal deflection spectroscopy, resulting in suboptimal overall device performance. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.