For nearly 100 y, homochiral ferroelectrics were basically multicomponent simple organic amine salts and metal coordination compounds. Single-component homochiral organic ferroelectric crystals with high-Curie temperature (T c ) phase transition were very rarely reported, although the first ferroelectric Rochelle salt discovered in 1920 is a homochiral metal coordination compound. Here, we report a pair of single-component organic enantiomorphic ferroelectrics, (R)-3-quinuclidinol and (S)-3-quinuclidinol, as well as the racemic mixture (Rac)-3-quinuclidinol. The homochiral (R)-and (S)-3-quinuclidinol crystallize in the enantiomorphic-polar point group 6 (C 6 ) at room temperature, showing mirror-image relationships in vibrational circular dichroism spectra and crystal structure. Both enantiomers exhibit 622F6-type ferroelectric phase transition with as high as 400 K [above that of BaTiO 3 (T c = 381 K)], showing very similar ferroelectricity and related properties, including sharp step-like dielectric anomaly from 5 to 17, high saturation polarization (7 μC/cm 2 ), low coercive field (15 kV/cm), and identical ferroelectric domains. Their racemic mixture (Rac)-3-quinuclidinol, however, adopts a centrosymmetric point group 2/m (C 2h ), undergoing a nonferroelectric high-temperature phase transition. This finding reveals the enormous benefits of homochirality in designing high-T c ferroelectrics, and sheds light on exploring homochiral ferroelectrics with great application. ferroelectricity | homochirality | enantiomer | ferroelectric domains

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Two-dimensional (2D) hybrid double perovskites have attracted extensive research interest for their fascinating physical properties, such as ferroelectricity, X-ray detection, light response and so on. In addition, ferroelastic, as an...

Surface passivation via post-treatment is an important strategy for improving power conversion efficiency and operational stability of perovskite solar cells. However, so far the interaction mechanisms between passivating additive and perovskite are not well understood. Here, we report the atomic-scale interaction of surface passivating additive 2,2-difluoroethylammonium bromine (2FEABr) on the MAPbI3. It is found that the bulky 2FEA+ cations tend to distribute at film surface, while the Br− anions diffuse from surface into bulk. A combination of 19F, 207Pb, and 2H solid-state NMR further reveal the Br− anions’ partial substitution for the I− sites, the restricted motion of partial MA+ cations, and the firmed perovskite lattices, which would improve charge transport and stability of the perovskite films. Optical spectroscopy and ultraviolet photoelectron spectroscopy demonstrate that the 2FEABr induced surface passivation and energetic modification suppress the nonradiative recombination loss. These findings enable the efficiency of the p-i-n structured PSC significantly increasing from 19.44 to 21.06%, accompanied by excellent stability. Our work further establishes more knowledge link between passivating additive and PSC performance.

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