Metal halide perovskites, as a new generation of optoelectronic materials, have attracted a great deal of interest due to their
remarkable intrinsic properties. Due to the excellent optoelectronic properties, the perovskite crystals are widely used in lasers,
photodetectors, X-ray detectors and solar cells. Considering the device performance and fabrication requirements, proper thickness
of the crystal is required to avoid carrier loss and simultaneously ensure sufficient light absorption, which can realize the full
potential of its excellent carrier transport property. Thus, the fabrication of perovskite crystal in a thin film with an adjustable thickness
is highly desirable. The space-confined method has been demonstrated to be an effective way of preparing perovskite with controlled
thickness. In this method, the thickness of perovskite can be regulated flexibly in a geometric confined space. Moreover, the size,
quality and architecture of perovskite crystal films are also major concerns for practical photoelectric devices, which can also
be optimized by the space-confined method owing to its good adaptability towards various modified strategies. In a word, the
space-confined method is not only a simple and conventional way to adjust the thickness of perovskite crystal films, but also
provides a platform to optimize their size, quality and architecture through applying appropriate strategies to the confined space.
Herein, we review the space-confined growth of perovskite crystal films. Particularly, various modified strategies based on the
space-confined method applied to the optimization of thickness, size, quality and architecture are highlighted. Then the stability
investigating and component regulating of perovskite crystal films would be also mentioned. Furthermore, the correlation between
the perovskite thickness and the device performance is discussed. Finally, several key challenges and proposed solutions of
perovskite thin films based on the space-confined method are discussed.