Despite intense research efforts, its performance as the most commonly used hole-transporting material in perovskite and dye-sensitized solar cells has remained stagnant, creating a major bottleneck for improving solar cell efficiency.
In general, perovskite solar cells and dye-sensitized solar cells are made of three critical layers.
The mesoscale packing structure of the hole-transporting layer, which is usually spiro-OMeTAD, has so far eluded researchers, and consequently its charge transport mechanisms have remained a mystery.
Although the method used here to grow single crystals cannot be performed at a large scale, the researchers predict that similar methods that use an antisolvent to trigger crystallization could be used to enhance the crystallinity of the thin-layer spiro-OMeTAD, improving its hole mobility in order to make more efficient solar cells.
“These astonishing findings open a new direction for the development of perovskite solar cells and dye-sensitized solar cells by showing the still untapped potential of spiro-OMeTAD,” Bakr said.
Abstract We report the crystal structure and hole-transport mechanism in spiro-OMeTAD , the dominant hole-transporting material in perovskite and solid-state dye-sensitized solar cells.
Despite spiro-OMeTAD’s paramount role in such devices, its crystal structure was unknown because of highly disordered solution-processed films; the hole-transport pathways remained ill-defined and the charge carrier mobilities were low, posing a major bottleneck for advancing cell efficiencies.