Changing the color of light hitting a crystal can actually decide whether it stays solid or starts to 'flow' like a slow-moving liquid.
April 17, 2026
Original Paper
Wavelength-dependent photo-creep in halide perovskite single crystals
arXiv · 2604.11848
The Takeaway
We usually think of light as just heat or energy, but in halide perovskite crystals, light wavelengths act like a physical remote control for the material's rigidity. Scientists found that certain colors of light accelerate 'creep'—the permanent deformation of a solid—while others can suppress it entirely. It’s a 'photomechanical' effect where photons are physically rearranging the structure of the crystal on the fly. This means we could build structural components that 'heal' themselves or change their shape just by being under a specific lamp. For the solar cell industry, where these materials are used, this explains why some panels fail and how we can use light to make them last much longer.
From the abstract
Halide perovskites are promising optoelectronic materials, but their time-dependent permanent deformation under illumination (i.e., photo-creep) is poorly understood, limiting their mechanical stability. Here we report wavelength-dependent photo-creep phenomena in CsPbBr3 and FAPbBr3 single crystals, studied by constant-load nanoindentation under controlled light with various wavelengths. Compared with creep in dark, continuous green light (near-bandgap) suppresses creep by 19% in CsPbBr3 and 10