Since the absorption spectra of carbon quantum dots are mainly concentrated in the ultraviolet region and nearly transparent to visible light, a new concept of ultraviolet photovoltaic window is proposed using carbon quantum dots as a light absorber. The photovoltaic window can generate electricity without affecting indoor lighting and effectively block the entry of ultraviolet light. Cotton fiber as carbon precursor and urea as dopant are used to prepare green N-doped carbon quantum dots with blue fluorescence. Moreover, the amount of dopant and thickness of TiO2 film have a great influence on the power conversion efficiency and transmittance of the photovoltaic window. The best efficiency of the photovoltaic window obtained is 0.614% and its average visible transmittance is also the best (37.2%) among the prepared photovoltaic windows. The construction of ultraviolet photovoltaic window successfully opens up a new application of carbon quantum dots in building-integrated photovoltaics.