Semitransparent all-polymer solar cells through lamination

Abstract

In this work, we demonstrate all-polymer solar cells where all the layers are made from polymers. We use PEDOT:PSS as the semitransparent anode and polyethyleneimine modified PEDOT:PSS as the semi-transparent cathode, both of which are slot-die printed on polyethylene terephthalate (PET). Active layers are deposited on the cathode and anode surfaces by spin coating separately. These layers are then joined through a roll-to-roll compatible lamination process. This results in a semitransparent and flexible solar cell. We have used two polymer–polymer systems and several combinations, and the highest power conversion efficiency (PCE) obtained is 2.3% with a mean transparency > 35% within the visible light range. By laminating a thin layer acceptor polymer to a thick polymer–polymer blend, we can improve the performance by reducing recombination, compared to laminating blend to blend, which is verified by the trap-limited charge transport, CELIV and electroluminescence.