Lignosulfonate-Induced orientation of Poly(3,4-ethlylenedioxythiophene) for enhanced efficiency in bifacial Dye-Sensitized solar cells

Bifacial dye-sensitized solar cells (DSSCs) have the potential to address the challenge of low photoelectric conversion efficiency (PCE) in various applications. However, achieving a harmonious alignment between the counter electrode (CE) structure and its crucial properties remains a significant challenge. Herein, a lignin-induced orientation strategy was developed for poly (3,4-ethylenedioxythiophene) (PEDOT) using lignosulfonate (SL) as both a surfactant and initiator during the electrochemical deposition process. This approach enabled the successful construction of high-performance CEs for DSSCs. The resulting SL/PEDOT CEs exhibited a low disordered orientation distribution and high redox capacity, achieving a high backside light absorption of 10.7 % and a high conductivity of 104 S/m. Additionally, SL/PEDOT CEs featured excellent corrosion resistance, high electro-catalytic activity, and long service life, maintaining over 90 % of their initial efficiency after 500h. Notably, the incorporation of SL into pristine PEDOT increased the number of electron transport sites, leading to an increase in short-circuit current densities from 21.49 to 29.04 mA/cm². Under one-sided and double-sided irradiation, DSSCs modified with SL/PEDOT CEs achieved higher PCE values of 9.49 % and 16.13 %, respectively, which exceeded those of numerous previously reported DSSCs. Benefiting from the matching effect between molecular/microstructure regulation and performance optimization resulting from SL-induced the orientation of PEDOT molecules, this work offers a new paradigm for the development of high-efficiency bifacial DSSCs.