Fig.1 Schematic of the core–shell perovskite nanocrystals with an achiral 3D MAPbI3 core and a chiral 2D shell (S-NEA). Owing to distinct absorption, 375 nm excitation preferentially engages the chiral shell and activates a CISS shell-to-core carrier-injection pathway, whereas 532 nm excitation predominantly populates the MAPbI3 core and largely bypasses the shell-mediated CISS pathway. These two excitation pathways lead to distinct CPL outputs with |glum| = 3.8 × 10−3 and 1.5 × 10−3, respectively.#

Fig.2 Structural and optical characterization of MAPbI3 core and R- and S-NEA/3D core–shell nanocrystals. (a) Photographs of S-NEA/3D dispersions prepared with different nominal PbI2-equivalent shell-precursor dosages (0.5, 1.0, 1.5, and 2.0 mM) under 375 nm UV illumination. (b) Powder XRD patterns of the reference tetragonal MAPbI3 phase, MAPbI3 nanocrystals, and S-NEA/3D samples. (c) FTIR spectra of S-2D, MAPbI3, and S-NEA/3D. HRTEM images of (d) MAPbI3 nanocrystals and (e) S-NEA/3D core–shell nanocrystals. (f) DLS size distributions of MAPbI3 nanocrystals and S-NEA/3D. (g) UV–vis absorption and photoluminescence (PL) spectra of S-2D, MAPbI3, and S-NEA/3D. (h) Time-resolved PL decays of MAPbI3 and S-NEA/3D recorded at λex = 365 nm. (i) CD spectra of S-NEA/3D and R-NEA/3D with the corresponding absorbance profile.#

在圆偏振发光测试中，375纳米激发下R-与S-NEA/3D样品呈现出清晰的镜面对称圆偏振发光信号，发光不对称因子绝对值达到3.8×10⁻³；而当激发波长切换至532纳米时，该值降至1.5×10⁻³，证实了激发波长对自旋注入效率的有效调控（如图3）。与此同时，磁导电力显微镜测量显示，手性壳层的自旋选择性输运可使自旋极化率达到85%，且R与S构型样品的极化方向相反，有力印证了手性诱导自旋选择性效应的存在。飞秒瞬态吸收光谱进一步揭示了激发波长依赖的载流子动力学过程：在375纳米激发下，全局分析解析出一个时间常数为48皮秒的中间组分，归属于壳层向核心的粒子数转移；而532纳米激发则直接布居核心态，该转移路径显著减弱（如图4）。这些实验证据从宏观发光、微观输运和超快动力学三个层面，共同支撑了波长控制自旋注入的物理图像。

Fig.3 Excitation-dependent CPL and spin-selective transport in R- and S-NEA/3D core–shell nanocrystals. CPL spectra of R-NEA/3D and S-NEA/3D measured under (a) 375 nm and (b) 532 nm excitation. (c) |glum| values of R- and S-NEA/3D under 375 and 532 nm excitation. mCP-AFM measurements of (d) R-NEA/3D and (e) S-NEA/3D. (f) Spin polarization (%) extracted from the CISS response.#

Fig.4 Excitation-wavelength-dependent ultrafast dynamics of S-NEA/3D core–shell perovskite nanocrystals. The fs-TA spectra of S-NEA/3D under (a) 375 nm and (b) 532 nm excitation. Representative TA spectra of S-NEA/3D at selected delay times following 375 nm excitation, shown for early-time evolution (c, 100 fs–3 ps) and subsequent relaxation (d, 3 ps–3 ns). EADS obtained from global analysis of fs-TA data for S-NEA/3D under (e) 375 nm excitation and for S-NEA/3D under (f) 532 nm excitation, with fitted time constants indicated in the legends. (g) Transient kinetics extracted at 521 nm from the S-NEA/3D heterostructure under 375 and 532 nm excitation, corresponding to the short-wavelength ESA signal. Excitation-polarization-dependent CPL spectra of S-NEA/3D under (h) 375 nm and (i) 532 nm excitation. σ+ and σ− denote right- and left-circularly polarized excitation, respectively. Solid lines represent averaged spectra from three repeated measurements, and shaded regions indicate standard deviations.#

Fig.5 Schematic illustration of excitation-pathway-dependent spin-polarized carrier injection and CPL output in the R- and S-NEA/3D core–shell heterostructure.#