Dithiafulvenyl Unit as a New Donor for High-Efficiency Dye-Sensitized Solar Cells: Synthesis and Demonstration of a Family of Metal-Free Organic Sensitizers

This work identifies the dithiafulvenyl unit as an excellent electron donor for constructing D−π–A-type metal-free organic sensitizers of dye-sensitized solar cells (DSCs). Synthesized and tested are three sensitizers all with this donor and a cyanoacrylic acid acceptor but differing in the phenyl (<b>DTF-C1</b>), biphenyl (<b>DTF-C2</b>), and phenyl–thiopheneyl–phenyl π-bridges (<b>DTF-C3</b>). Devices based on these dyes exhibit a dramatically improved performance with the increasing π-bridge length, culminating with DTF-C3 in η = 8.29% under standard global AM 1.5 illumination

Synthesis and Properties of Dithiafulvenyl Functionalized Spiro[fluorene-9,9′-xanthene] Molecules

Two spiroannulated molecular structures with dithiafulvenyl units functionalized at the 2,2′,7,7′- (<b>SFX-DTF1</b>) and 2,3′,6,′7- (<b>SFX-DTF2</b>) positions of a spiro­[fluorene-9,9′-xanthene] core were synthesized. Studies revealed the hole mobility was significantly influenced by the dithiafulvenyl functionalized positions in the molecular structure. To explore their primary applications as hole-transporting materials in perovskite solar cells, <b>SFX-DTF1</b>-based devices exhibited a power conversion efficiency of 10.67% without the use of p-type dopants, yielding good air stability