Due to their layered structure, two-dimensional Ruddlesden–Popper perovskites (RPPs), composed of multiple organic/inorganic quantum wells, can in principle be exfoliated down to few and single layers. These molecularly thin layers are expected to present unique properties with respect to the bulk counterpart, due to increased lattice deformations caused by interface strain. Here, we have synthesized centimetre-sized, pure-phase single-crystal RPP perovskites (CH₃(CH₂)₃NH₃)₂(CH₃NH₃)_n−1Pb_nI_3n+1 (n = 1–4) from which single quantum well layers have been exfoliated. We observed a reversible shift in excitonic energies induced by laser annealing on exfoliated layers encapsulated by hexagonal boron nitride. Moreover, a highly efficient photodetector was fabricated using a molecularly thin n = 4 RPP crystal, showing a photogain of 10⁵ and an internal quantum efficiency of ~34%. Our results suggest that, thanks to their dynamic structure, atomically thin perovskites enable an additional degree of control for the bandgap engineering of these materials

由于其分层结构，原则上可以将由多个有机/无机量子阱组成的二维Ruddlesden-Popper钙钛矿（RPP）剥落至很少和单层。由于由界面应变引起的晶格变形增加，因此这些分子薄层相对于本体对应物将表现出独特的性能。在这里，我们合成了厘米级的纯相RPP钙钛矿（CH ₃（CH ₂）₃ NH ₃）₂（CH ₃ NH ₃）_{n -1} Pb _n I _{3 n +1}（n = 1-4）剥落了单个量子阱层。我们观察到由激光退火在六角形氮化硼封装的剥离层上引起的激子能量的可逆变化。此外，使用分子薄的n  = 4 RPP晶体制造了高效的光电探测器，其光增益为10 ⁵，内部量子效率为〜34 ％。我们的结果表明，由于其动态结构，原子薄的钙钛矿为这些材料的带隙工程提供了更高程度的控制