Bifacial Perovskite Solar Cells by Lamination Approach With a PEDOT:PSS/d-Sorbitol Blended Adhesion Layer

Bifacial perovskite solar cells (PSCs) generate electricity by absorbing light from both their front and rear sides. These PSCs are constructed by laminating two prefabricated half-cells into a bifacial device. However, insulating lamination layers can degrade adjacent layers and increase series resistance, thereby compromising device performance. Herein, we present an efficient lamination method for bifacial PSCs under low-temperature and low-pressure conditions. Specifically, a blend of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and a hydroxyl-rich compound, d-sorbitol, is employed as a conductive adhesive layer. We incorporated d-sorbitol into PEDOT:PSS to provide adhesive character and enable lamination of the two substrates. We also found that hydrogen bonding between d-sorbitol and PSS reduces the Coulombic attraction between PEDOT and PSS. This promotes rearrangement of the PEDOT chains into a more closely packed structure with enhanced π-π stacking. These changes improve conductivity and surface uniformity. As a result, the conductive adhesion layer enables an intimate interconnection between the two laminated components of the laminated bifacial PSCs (LBPs). Notably, the optimal LBP exhibits a power conversion efficiency of 19.17% under 1-sun illumination and 27.54% at an albedo value of 0.5. Overall, this lamination strategy provides an effective approach to fabricate efficient bifacial PSCs under low-temperature and low-pressure conditions.