Chiral Bifacial Indacenodithiophene‐Based Hole‐Transport Materials With Chirality‐Induced Spin Selectivity: Chirality‐Spin Polarity Correspondence and Perovskite Passivation

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Abstract
Chirality‐induced spin selectivity (CISS) is emerging as a key element for spin‐dependent functions in organic electronics. We previously developed a chiral bifacial indacenodithiophene (IDT) backbone that shows strong CISS in both π ‐conjugated polymers and non‐fullerene acceptors (NFAs). Building on this platform, here we report triarylamine‐functionalized, chiral bifacial IDT‐based hole‐transport materials (HTMs). Spin‐coated films of ( R , R )‐ 1 and ( S , S )‐ 1 exhibit pronounced CISS with spin polarization (SP) ≈ 60%. Across our chiral‐bifacial IDT series, π ‐conjugated polymers, NFAs, and these HTMs, we observe a consistent chirality‐spin polarity correspondence: ( S , S ) chirality yields negative SP, whereas ( R , R ) yields positive SP, representing a platform‐level demonstration across three material classes. In perovskite solar cells, these HTMs also act as effective surface passivators; devices passivated with homochiral ( R , R )‐ 1 gave higher efficiencies than meso ‐ or racemic counterparts. Space–charge‐limited current measurements likewise indicate approximately threefold higher hole mobility for the homochiral film relative to the racemate. While a direct causal connection to the CISS effect remains to be demonstrated, these observations are consistent with a CISS‐assisted, efficient spin‐selective transport mechanism. Taken together, this work establishes a chirality‐spin polarity correspondence and demonstrates effective perovskite passivation, with higher hole mobility correlating with homochirality, highlighting new opportunities for homochiral materials in device science.
Funding Information
  • Japan Society for the Promotion of Science (JP23H02013)
  • Japan Society for the Promotion of Science (JP22H04541)
  • Japan Society for the Promotion of Science (JP23H04626)
  • Japan Society for the Promotion of Science (JP25H01409)
  • Japan Society for the Promotion of Science (JP20H05836)
  • Japan Society for the Promotion of Science (JP24H00484)

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