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Abstract Rational design of chiral two‐dimensional hybrid organic–inorganic perovskites is crucial to achieve chiroptoelecronic, spintronic, and ferroelectric applications. Here, an efficient way to manipulate the chiroptoelectronic activity of 2D lead iodide perovskites is reported by forming mixed chiral (R‐ or S‐methylbenzylammonium (R‐MBA⁺or S‐MBA⁺)) and achiral (n‐butylammonium (nBA⁺)) cations in the organic layer. The strongest and flipped circular dichroism signals are observed in (R/S‐MBA_0.5nBA_0.5)₂PbI₄films compared to (R/S‐MBA)₂PbI₄. Moreover, the (R/S‐MBA_0.5nBA_0.5)₂PbI₄films exhibit pseudo‐symmetric, unchanged circularly polarized photoluminescence peak as temperature increases. First‐principles calculations reveal that mixed chiral–achiral cations enhance the asymmetric hydrogen‐bonding interaction between the organic and inorganic layers, causing more structural distortion, thus, larger spin‐polarized band‐splitting than pure chiral cations. Temperature‐dependent powder X‐ray diffraction and pair distribution function structure studies show the compressed intralayer lattice with enlarged interlayer spacing and increased local ordering. Overall, this work demonstrates a new method to tune chiral and chiroptoelectronic properties and reveals their atomic scale structural origins. 

Abstract 2D‐on‐3D (2D/3D) perovskite heterostructures present a promising strategy to realize efficient and stable photovoltaics. However, their applicability in inverted solar cells is limited due to the quantum confinement of the 2D‐layer and solvent incompatibilities that disrupt the underlying 3D layer, hampering electron transport at the 2D/3D interface. Herein, solvent‐dependent formation dynamics and structural evolution of 2D/3D heterostructures are investigated via in situ X‐ray scattering. It is revealed that solvent interaction with the 3D surface determines the formation sequence and spatial distribution of quasi‐2D phases withn= 2–4. Isopropanol (IPA) reconstructs the perovskite into a PbI₂‐rich surface, forming a strata with smallernfirst, followed by a thinner substratum of largern. In contrast, 2,2,2‐Trifluoroethanol (TFE) preserves the 3D surface, promoting the formation of uniformly distributed largerndomains first, and smallernlast. Leveraging these insights, Dion–Jacobson perovskites are used with superior charge transport properties and structural robustness to fabricate 2D/3D heterostructures dominated byn≥ 3 and engineer a favorable energy landscape for electron tunneling. Inverted solar cells based on 3‐Aminomethylpyridine and TFE achieve a champion efficiency of 23.60%, withV_ocand FF of 1.19 V and 84.5%, respectively, and superior stabilities witht₉₄of 960 h under thermal stress. 

Recently, carbazole-based organic cations have garnered interest for their potential application in two-dimensional (2D) layered hybrid perovskite solar cells because of their strong hole extraction and transport as well as humidity resistance. However, the potential incorporation of carbazole-based Ruddlesden–Popper 2D hybrid perovskites in photodetectors has been largely unexplored. In this study, we synthesized ammonium 1-(9H-carbazol-9-yl) ethanaminium iodide (CzEAI) and fabricated (CzEA)2PbI4 2D perovskite thin films via varying solvent conditions to control film morphology. We constructed photodiode-type photodetectors with the active layer of (CzEA)2PbI4 2D perovskites and demonstrated a specific detectivity of 6.95 × 1010 Jones at 485 nm illumination without external bias. These results demonstrate the potential of carbazole-based 2D perovskites in a wide range of optoelectronic applications.