Colloidal heterostructured quantum dots (QDs) are promising candidates for next‐generation optoelectronic devices. In particular, “giant” core/shell QDs (g‐QDs) can be engineered to exhibit outstanding optical properties and high chemical/photostability for the fabrication of high‐performance optoelectronic devices. Here, the synthesis of heterostructured CuInSe_xS_2−x (CISeS)/CdSeS/CdS g‐QDs with pyramidal shape by using a facile two‐step method is reported. The CdSeS/CdS shell is demonstrated to have a pure zinc blend phase other than typical wurtzite phase. The as‐obtained heterostructured g‐QDs exhibit near‐infrared photoluminescence (PL) emission (≈830 nm) and very long PL lifetime (in the microsecond range). The pyramidal g‐QDs exhibit a quasi‐type II band structure with spatial separation of electron–hole wave function, suggesting an efficient exciton extraction and transport, which is consistent with theoretical calculations. These heterostructured g‐QDs are used as light harvesters to fabricate a photoelectrochemical cell, exhibiting a saturated photocurrent density as high as ≈5.5 mA cm⁻² and good stability under 1 sun illumination (AM 1.5 G, 100 mW cm⁻²). These results are an important step toward using heterostructured pyramidal g‐QDs for prospective applications in solar technologies.

中文翻译：

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近红外胶体异质结构金字塔“巨型”核/壳量子点的光电特性

胶体异质结构量子点（QD）是下一代光电器件的有希望的候选者。特别是，“巨型”核/壳量子点（g-QD）可以被设计为表现出出色的光学特性和高化学/光稳定性，用于制造高性能光电器件。在这里，报道了通过使用简单的两步法合成具有金字塔形状的异质结构 CuInSe _x S _{2− x (CISeS)/CdSeS/CdS g-QD。}CdSeS/CdS 壳被证明具有除典型纤锌矿相之外的纯锌混合相。所获得的异质结构 g-QD 表现出近红外光致发光（PL）发射（约 830 nm）和非常长的 PL 寿命（在微秒范围内）。金字塔形g-QD表现出准II型能带结构，电子-空穴波函数空间分离，表明其具有有效的激子提取和传输，这与理论计算一致。这些异质结构g-QD被用作光捕获器来制造光电化学电池，表现出高达约5.5 mA cm ^{-2 的}饱和光电流密度，并且在1个太阳光照（AM 1.5 G，100 mW cm ^-2）下具有良好的稳定性。这些结果是使用异质结构金字塔 g-QD 在太阳能技术中进行前瞻性应用的重要一步。