Electronic structures and optical properties of organic dye sensitizer NKX derivatives for solar cells: A theoretical approach

The photon to current conversion efficiency of dye-sensitized solar cells (DSCs) can be significantly affected by dye sensitizers. The design of novel dye sensitizers with good performance in DSCs depend on the dye's information about electronic structures and optical properties. Here, the geometries, electronic structures, as well as the dipole moments and polarizabilities of organic dye sensitizers C343 and 20 kinds of NKX derivatives were calculated using density functional theory (DFT), and the computations of the time dependent DFT with different functionals were performed to explore the electronic absorption properties. Based upon the calculated results and the reported experimental work, we analyzed the role of different conjugate bridges, chromophores, and electron acceptor groups in tuning the geometries, electronic structures, optical properties of dye sensitizers, and the effects on the parameters of DSCs were also investigated.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (162 K)Download as PowerPoint slideHighlights► The conjugation from bridge to acceptor is favorable to improve dye performance. ► Strong pull-electron group in acceptor generates larger electric potential barrier and Voc. ► Elongating alkenyl and thiophene chain in bridge result in smaller driving force. ► Elongating alkenyl chain generates larger oscillator strength and fast CT. ► The dyes with higher Jsc have more excited states with CT character.