Cooptimization of Adhesion and Power Conversion Efficiency of Organic Solar Cells by Controlling Surface Energy of Buffer Layers

• Published in: ACS applied materials & interfaces Vol. 9; no. 42; pp. 37395 - 37401
• Main Authors: Lee, Inhwa, Noh, Jonghyeon, Lee, Jung-Yong, Kim, Taek-Soo
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 25-10-2017
• Subjects: work of adhesion; organic solar cell; interfacial fracture energy; surface energy; buffer layer
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.7b10398

Here, we demonstrate the cooptimization of the interfacial fracture energy and power conversion efficiency (PCE) of poly­[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT)-based organic solar cells (OSCs) by surface treatments of the buffer layer. The investigated surface treatments of the buffer layer simultaneously changed the crack path and interfacial fracture energy of OSCs under mechanical stress and the work function of the buffer layer. To investigate the effects of surface treatments, the work of adhesion values were calculated and matched with the experimental results based on the Owens–Wendt model. Subsequently, we fabricated OSCs on surface-treated buffer layers. In particular, ZnO layers treated with poly­[(9,9-bis­(3′-(N,N-dimethyl­amino)­propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) simultaneously satisfied the high mechanical reliability and PCE of OSCs by achieving high work of adhesion and optimized work function.