In an effort to reduce the size of optical spectrometers, researchers have been working on developing miniature on-chip spectrometers that could be integrated into small handheld devices or even smartphones. Now, reducing the size down to the micrometer scale, researchers have developed a single-dot spectrometer based on an in situ modulated perovskite photodetector. The device is enabled by photogain manipulation controlled by ion redistribution in the perovskite film under an externally ...