The authors investigate how chiral ligands attached to perovskite nanocrystal (PNC) surfaces structurally distort the perovskite lattice. Chiral electro-optical properties of the resulting PNCs are demonstrated through the fabrication of a circularly polarized light (CPL) detector with a discrimination of up to 14% between left- and right-handed CPL. Both experimental and electronic-struc- ture-based simulations are combined to provide insights into the interactions (both structural and electronic) between chiral organic ligands and PNCs. The major finding is a centro-asymmetric distortion of the surface lattice that penetrates up to five atomic unit cells deep into the PNCs, which is the likely cause of the chiral-optical properties. Spin-polarized transport through chiral- PNCs results from the chiral-induced spin selectivity effect and amplifies the discrimination between left and right-handed CPL as is experimentally demonstrated in the detectors.
In conclusion, we couple theoretical simulations to the experi mentally observed chiroptical response and photophysical properties of colloidal chiral CsPbBr3 PNC thin films to formally understand the chiral transfer mechanism. R/SMBA:Br chiral ligands transfer chirality into PNCs by distorting the five out ermost layers of surface octahedra, resulting in a symmetry breaking and slightly reduced bandgap. We find that chiral surface ligands increase the PLQE of PNCs by suppressing nonradiative recombination and facilitating radiative recombi nation. Additionally, we show that chiral PNCs can work as a CPL detector with detectivity of up to 14%. Our experimental and theoretical approach toward understanding the effects of chiral ligands on PNCs provides a path toward further spinoptoelectronics based on colloidal PNCs.
Read the full article at Advanced Functional Materials
Adv. Funct. Mater. 2022, 2200454
Young-Hoon Kim, Ruyi Song, Ji Hao, Yaxin Zhai, Liang Yan, Taylor Moot, Axel F. Palmstrom, Roman Brunecky, Wei You, Joseph J. Berry, Jeffrey L. Blackburn, Matthew C. Beard, Volker Blum, Joseph M. Luther
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