Interlayer Modification Using Eco-friendly Glucose-Based Natural Polymers in Polymer Solar Cells

Applying biomaterials in optoelectronic devices has recently received great research interests since they not only possess economic benefits but also can facilitate the sustainable development of technology. We herein investigated the effectiveness of glucose-based biopolymers as zinc oxide surface modifiers in inverted OPVs by rationally studying chitosan, methyl-cellulose, and dextrin. Owing to the proper side-group and configurational modification, these three biopolymers possess better solution processability and film-formation capability than the pristine cellulose. Besides, their abundant availability in the environment renders them to be easily accessible and more economical as compared to other commonly used polymeric interlayers. Our results reveal the critical structure-performance relationship of these glucose-based biopolymers and their derived OPVs. In particular, the beta-type glucose-based polymer, methyl-cellulose, was demonstrated as the most efficient modifying interlayer for ZnO ETL, which enables 9.47% and 6.34% enhancement in PCE for the representative fullerene- and NFA-based BHJ systems (PTB7-Th:PC71BM and PBDB-T:ITIC), respectively, as compared to the control devices. Detailed functions of these glucose-based polymeric interlayers in the device were carefully analyzed. The study provides a new perspective of the interlayer design for OPVs, which can facilitate their sustainable development.