The influence of an inner electric field on the performance of three types of Zn-porphyrin sensitizers in dye sensitized solar cells: a theoretical study
It is well-known that the inner electric field formed between the counter electrode and the semiconductor surface has a substantial effect on the efficiencies of dye-sensitized solar cells (DSSCs). To reveal the function of the inner electric field for different types of porphyrin sensitizers in DSSCs, the properties of three types of porphyrin sensitizers (α, β, and center axial positions) under different electric fields were calculated by using density functional theory (DFT) and time dependent density functional theory (TD-DFT). The electronic structures and optical properties of these studied dyes in tetrahydrofuran (THF) solution were also investigated correspondingly. Key parameters of the short-circuit current density (Jsc) including light harvesting efficiency (LHE), electron injection driving force (ΔGinject) and intramolecular charge transfer (ICT) were detailedly discussed. The results show that the a-position type porphyrin sensitizer can be used as a potential sensitizer for DSSCs under an enhanced electric field. We expect that the present study would deepen the understanding of the function of an inner electric field and may be helpful in DSSC design in the future.