Realizing solution-processed heterostructures is a long-enduring challenge in halide perovskites because of solvent incompatibilities that disrupt the underlying layer. By leveraging the solvent dielectric constant and Gutmann donor number, we could grow phase-pure two-dimensional (2D) halide perovskite stacks of the desired composition, thickness, and bandgap onto 3D perovskites without dissolving the underlying substrate. Characterization reveals a 3D–2D transition region of 20 nanometers mainly determined by the roughness of the bottom 3D layer. Thickness dependence of the 2D perovskite layer reveals the anticipated trends for n-i-p and p-i-n architectures, which is consistent with band alignment and carrier transport limits for 2D perovskites. We measured a photovoltaic efficiency of 24.5%, with exceptional stability of T 99 (time required to preserve 99% of initial photovoltaic efficiency) of >2000 hours, implying that the 3D/2D bilayer inherits the intrinsic durability of 2D perovskite without compromising efficiency.

中文翻译：

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用于耐用和高效太阳能电池的 3D/2D 钙钛矿双层堆栈的确定性制造

由于溶剂不相容性会破坏底层，因此实现溶液处理的异质结构是卤化物钙钛矿的长期挑战。通过利用溶剂介电常数和 Gutmann 供体数，我们可以在 3D 钙钛矿上生长具有所需成分、厚度和带隙的相纯二维 (2D) 卤化物钙钛矿叠层，而不会溶解下面的基板。表征揭示了一个 20 纳米的 3D-2D 过渡区域，主要由底部 3D 层的粗糙度决定。二维钙钛矿层的厚度依赖性揭示了 nip 和 pin 结构的预期趋势，这与二维钙钛矿的能带排列和载流子传输限制一致。我们测得的光伏效率为 24.5%，具有出色的稳定性吨 99（保持 99% 的初始光伏效率所需的时间）> 2000 小时，这意味着 3D/2D 双层继承了 2D 钙钛矿的固有耐久性而不影响效率。