Effects of buffer layers on properties of bulk hetero junction flexible organic solar cells

摘要

We fabricated the flexible organic solar cells (OSCs) using the alternating co-polymer, poly[iV-9"-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',l',3'-benzothiadiazole) (PCDTBT) in bulk hetero junction composites with the fullerene derivative [6,6]-phenyl C_(61)-butyric acid methyl ester (PCBM) active layer for the electron donor and acceptor materials, respectively. The active layer was spin-coated onto various substrates with different buffer layers of lithium fluoride (LiF) and poly(3,4-ethylenedioxythiophene):poly(styr-cnesulfonate) (PEDOT:PSS) on the indium tin oxide (ITO) coated polyethylene naphthalene (PEN) substrates, such as PEN/ITO/LiF, PEN/1TO/PEDOT:PSS and PEN/ITO/PEDOT:PSS/LiF. The effects of the buffer layer position on the electrical and morphological properties of the devices were investigated. The performance of OSCs coated on the PEN/ITO/PEDOT:PSS/LiF substrate exhibited the best electrical property among the prepared samples, showing the maximum short circuit current, open circuit voltage, fill factor and power conversion efficiency values were about 11.4mA/cm~2, 0.90 V, 39.3 % and 4.0 %, respectively.