the present invention discloses a method for preparing heteroatom doped carbon quantum dot , and application thereof in fields of biomedicine , catalysts , photoelectric devices , etc . the various kinds of heteroatom doped carbon quantum dots are obtained by using a conjugated polymer as a precursor and through a process of high temperature carbonization . these carbon quantum dots contain one or more heteroatoms selected from the group consisting of n , s , si , se , p , as , ge , gd , b , sb and te , the absorption spectrum of which ranges from 300 to 850 nm , and the fluorescence emission wavelength of which is within a range of 350 to 1000 nm . the carbon quantum dot has a broad application prospect in serving as a new type photosensitizer , preparing drugs for photodynamic therapy of cancer and sterilization , photocatalytic degradation of organic pollutants , photocatalytic water - splitting for hydrogen generation , organic polymer solar cell and quantum dot - sensitized solar cell .