Halide perovskites are remarkable optoelectronic semiconductors because their optical response is strongly linked to crystal structure, dimensionality, defects, and dynamic disorder. While bulk single crystals provide access to intrinsic material properties, low-dimensional single-crystalline perovskite nanocrystals offer a complementary platform in which size, shape, and surface chemistry can be precisely varied and correlated with optical performance. In this talk, I will discuss how advanced synthesis, in situ characterization, and data-driven analysis can reveal structure–property relationships in halide perovskites from the single-particle to the ensemble level.

I will first present our recent work on the formation of anisotropic CsPbBr₃ nanocrystals, where simultaneous in situ X-ray scattering and photoluminescence spectroscopy revealed how emissive crystalline intermediates evolve into either one-dimensional nanorods or two-dimensional nanoplatelets [1]. These results show how antisolvent properties and ligand-mediated assembly pathways determine crystal dimensionality, structural order, and emission energy.

Building on this mechanistic understanding, I will discuss a chemistry-aware machine-learning framework for precision control of perovskite nanocrystal growth [2]. By combining automated synthesis, high-throughput optical characterization, Gaussian-process regression, and Bayesian optimization, this approach enables data-efficient navigation of complex synthesis spaces and yields nanocrystal ensembles with targeted emission properties and improved homogeneity.

The second part of the talk will focus on how optical spectroscopy can be used to extract intrinsic information from perovskite nanocrystals. I will introduce a statistical framework that links asymmetric photoluminescence lineshapes to exciton thermodynamics, energetic disorder, and size dispersion [3]. Finally, I will show how combined interferometric scattering and photoluminescence microscopy enables high-throughput determination of size and quantum yield for thousands of individual CsPbBr₃ nanocrystals in situ [4]. This single-particle approach uncovers heterogeneity, size-dependent defect passivation, and light-induced degradation pathways that are hidden in ensemble-averaged measurements.

Together, these studies establish a quantitative framework for connecting crystal growth, structural heterogeneity, defects, and optical functionality in halide perovskites. They highlight how low-dimensional perovskite single crystals can serve as model systems for understanding the microscopic mechanisms that ultimately limit performance, stability, and reproducibility in perovskite optoelectronics.