We present a cation-exchange approach for tunable A-site alloys of cesium (Cs⁺) and formamidinium (FA⁺) lead triiodide perovskite nanocrystals that enables the formation of compositions spanning the complete range of Cs_1–xFA_xPbI₃, unlike thin-film alloys or the direct synthesis of alloyed perovskite nanocrystals. These materials show bright and finely tunable emission in the red and near-infrared range between 650 and 800 nm. The activation energy for the miscibility between Cs⁺ and FA⁺ is measured (∼0.65 eV) and is shown to be higher than reported for X-site exchange in lead halide perovskites. We use these alloyed colloidal perovskite quantum dots to fabricate photovoltaic devices. In addition to the expanded compositional range for Cs_1–xFA_xPbI₃ materials, the quantum dot solar cells exhibit high open-circuit voltage (V_OC) with a lower loss than the thin-film perovskite devices of similar compositions.

中文翻译：

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钙钛矿型量子点光伏材料超出了薄膜范围：A站点阳离子组成的全范围调整

我们提出了铯（Cs的可调谐A位合金阳离子交换方法⁺）和甲脒（FA ⁺）碘化铅钙钛矿的纳米晶体，使跨越Cs的完整范围组合物的形成_{1- X} FA _X碘化铅₃，不像薄膜合金或钙钛矿纳米晶体合金的直接合成。这些材料在650至800 nm的红色和近红外范围内显示出明亮且可微调的发射。Cs ⁺与FA ⁺之间可混溶的活化能的测量值（约0.65 eV）显示为比报道的卤化钙钛矿中X位交换所报道的要高。我们使用这些合金化的胶态钙钛矿量子点来制造光伏器件。除了扩展了Cs _{1– x} FA _x PbI ₃材料的成分范围外，量子点太阳能电池还具有高开路电压（V _OC），且损耗比同类成分的钙钛矿薄膜器件低。