Metal halide perovskite semiconductors possess outstanding characteristics for optoelectronic applications including but not limited to photovoltaics. Low-dimensional and nanostructured motifs impart added functionality which can be exploited further. Moreover, wider cation composition tunability and tunable surface ligand properties of colloidal quantum dot (QD) perovskites now enable unprecedented device architectures which differ from thin-film perovskites fabricated from solvated molecular precursors. Here, using layer-by-layer deposition of perovskite QDs, we demonstrate solar cells with abrupt compositional changes throughout the perovskite film. We utilize this ability to abruptly control composition to create an internal heterojunction that facilitates charge separation at the internal interface leading to improved photocarrier harvesting. We show how the photovoltaic performance depends upon the heterojunction position, as well as the composition of each component, and we describe an architecture that greatly improves the performance of perovskite QD photovoltaics.

金属卤化物钙钛矿半导体具有用于光电应用（包括但不限于光伏）的出色特性。低维和纳米结构的图案赋予了更多的功能，可以进一步加以利用。此外，胶体量子点（QD）钙钛矿的更宽的阳离子组成可调谐性和可调谐的表面配体特性，现在可实现前所未有的器件架构，与由溶剂化分子前体制成的薄膜钙钛矿不同。在这里，使用钙钛矿量子点的逐层沉积，我们证明了整个钙钛矿薄膜中太阳能电池的成分发生突然变化。我们利用这种能力来突然控制成分，以创建内部异质结，从而促进内部界面处的电荷分离，从而改善光载流子的收集。