Perovskite colloidal quantum dots (Pe-CQDs) are highly promising nanocrystals for optoelectronic applications. However, the size of the crystals should ideally be equal to ensure a consistent energy landscape. In a recent study, scientists clarified the relationship between differences in particle size -- polydispersity -- and the optoelectronic characteristics of Pe-CQDs. They showed that using equally sized, or 'monodisperse,' quantum dots results in markedly better performance in Pe-CQD solar cells, paving the way for future optoelectronic devices.