Mirror-image molecules steer electron spins and lift perovskite solar cell efficiency
Some molecules come in two "handed" forms. This property, called chirality, can influence not only how molecules interact with light but also which electron spins they allow to pass. Researchers at the University of Osaka have developed novel chiral hole-transport materials that shed new light on this unusual effect while also improving the interfaces of perovskite solar cells.
Researchers at the University of Osaka have discovered how mirror-image molecules can enhance the efficiency of perovskite solar cells by controlling electron spins. These chirality-induced spin selectivity (CISS) molecules come in two forms, (S,S) and (R,R), which exhibit opposite spin preferences. The (S,S) form favors negative spin polarization, while the (R,R) form promotes positive polarization.
In experiments, these chiral hole-transport materials demonstrated spin polarization of 60%, with the (R,R) material showing nearly three times faster hole mobility compared to racemic and nonchiral counterparts. When incorporated as a thin layer on perovskite solar cells, the (R,R) enantiomer improved power conversion efficiency from 19.48% to 20.64%.
The findings suggest a strong connection between molecular handedness and both spin preference and charge transport properties in organic electronic materials.
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