Interaction of pyridine π-bridge-based poly(methacrylate) dyes for the fabrication of dye-sensitized solar cells with the influence of different strength phenothiazine, fluorene and anthracene sensitizers as donor units with new anchoring mode

Abstract

Herein, we report three new metal-free organic polymer sensitizers with the pyridine (PYN) π-bridge, having the structure (donor)₂–π–acceptor ((D₂)–π–A). They were labelled as PPNPP, FPNPP, and APNPP due to the presence of a molecular framework, and used as photosensitizers for dye-sensitized solar cell (DSSC). Phenothiazine, fluorene and anthracene serve as the electron donor groups, nitrobenzene serves as the electron acceptor group, and pyridine serves as the π-bridge group. The detailed investigation of the relationship between the structure, thermal properties, electrochemical properties, and performance of DSSC is described herein. Furthermore, DFT studies were performed using the Gaussian 09 program with the B3LYP functional and 6-31G* basis set to evaluate their optimized geometry and HOMO–LUMO levels. The introduction of these three different donor units can drastically improve the sunlight-harvesting ability of DSSCs and the electron recombination, thus improving their performance. The polymer PPNPP shows a maximum power conversion efficiency (PCE, h) of 2.1%, which was achieved for the photovoltaic devices under AM 1.5 solar radiation (100 mW cm⁻²). With the addition of 10 mM CDCA as a co-adsorbent, the best performing cells based on the polymer dye PPNPP exhibit an impressive conversion efficiency of 4.12% (J_sc = 7.23 mA cm², V_oc = 0.76 V, FF = 69%).