Here, the authors report the growth of millimetre-scale 2D PbI2 single crystals via the spontaneous accumulation and in-plane arrangement of iodide ions at the water-air interface. The metal iodide crystals could be thinned down to a single monolayer via water etching, and subsequently converted into perovskite optoelectronic devices.
- Jingxian Zhong
- Dawei Zhou
- Lin Wang
