Multiple morphologies of colloidal perovskite nanocrystals (NCs) diversify their optical and electronic properties. Among them, the linear absorption cross-section (σ) is a primary parameter to determine their intrinsic photophysical features, and consequently, application potential. Herein, three morphologies of all-inorganic hybrid colloidal perovskite CsPbBr₃ NCs, nanocubes (NBs), nanoplatelets (NLs), and nanowires (NWs), were targeted, and their linear σ values were obtained through femtosecond transient absorption (TA) spectroscopy analysis. At high excitation energy well above the bandgap, the σ per particle of all CsPbBr₃ NCs linearly increased with the particle volume (V_NC) regardless of the morphology with the value of σ₄₀₀ = 9.45 × 10⁴ cm⁻¹ × V_NC (cm²). Density functional theory (DFT) calculation confirmed the negligible influence of shapes on the optical selection rules. The Einstein spontaneous emission coefficients calculated from the σ values define the intrinsic radiative recombination rate. However, reduced size dependence is observed when the excitation energy is close to the bandgap (i.e., at 460 nm) with the value of σ₄₆₀ = 2.82 × 10⁸ cm^0.65 × (V_NC)^0.45 (cm²). This should be ascribed to the discrete energy levels as well as lower density of states close to the band edge for perovskite NCs. These results provide in-depth insight into the optical characteristics for perovskite NCs.

胶态钙钛矿纳米晶体（NCs）的多种形态使其光学和电子特性多样化。其中，线性吸收截面（σ）是确定其固有的光物理特征以及因此具有应用潜力的主要参数。本文以全无机杂化胶体钙钛矿CsPbBr ₃ NCs，纳米立方（NBs），纳米血小板（NLs）和纳米线（NWs）的三种形态为目标，并通过飞秒瞬态吸收（TA）光谱分析获得了它们的线性σ值。 。在远高于带隙的高激发能下，所有CsPbBr ₃ NC的每个粒子的σ随粒子体积线性增加（V _NC）不管与值形态的σ ₄₀₀ = 9.45×10 ⁴厘米^-1 × V _NC（厘米²）。密度泛函理论（DFT）的计算证实了形状对光学选择规则的影响可忽略不计。根据σ值计算出的爱因斯坦自发发射系数定义了固有辐射复合率。然而，减小的尺寸依赖性，观察到当激励能量是接近带隙（即，在460nm）同值σ ₄₆₀ = 2.82×10 ⁸厘米^0.65 ×（V _NC）^0.45（厘米²）。这应归因于钙钛矿型NC的离散能级以及靠近带边缘的较低态密度。这些结果为钙钛矿NC的光学特性提供了深入的了解。