Enhancing efficiency and decelerating degradation in bulk heterojunction solar cells with N,N-Dimethylformamide cosolvent for poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)

Abstract

Focused on the improvement of hole transport layer of organic solar cells based on poly(3-hexylthiophene) (P3HT)/6,6-phenil C61-butyric acid methyl ester (PCBM) blend, we studied the possibility of extending the lifetime of these devices. Thus, influence of N,N-dimethylformamide (DMF) added to poly(3,4-ethylenedioxythiofene):poly(styrenesulfonate) (PEDOT:PSS) hole transport layer was analyzed. We report that DMF causes an increase in the power conversion efficiency (PCE) of organic solar cells. A likely reason for this improvement might be a reduced intermolecular distance between the poly(3,4-ethylenedioxythiofene): (PEDOT) and poly(styrenesulfonate) (PSS) chains. The optimal volume of DMF in PEDOT:PSS was studied: two parts of DMF to one part of PEDOT:PSS increases PCE by 47%. Furthermore, PEDOT:PSS layer with DMF generated a reduction in the degradation of PCE, extending the lifetime of bulk heterojunction solar cells.