© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Gold quantum dots (AuQDs) are employed as photosensitizers in organic thin-film solar cells (OSCs) to improve their photoelectric conversion properties. Three types of AuQDs with different fluorescence emission wavelengths are used: blue (B-AuQDs), green (G-AuQDs), and red (R-AuQDs). AuQDs are loaded into the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) thin-film layer of OSCs. UV–vis spectra, atomic force microscope images, current density–voltage characteristics, and impedance spectra of the fabricated devices are measured for the three aforementioned types of AuQDs. All types of AuQDs improve the photoelectric conversion properties, and the G-AuQD-loaded OSCs exhibit the best improvement, exhibiting an efficiency increase of 10% compared with OSCs without the AuQDs. The fluorescence/photosensitization of the AuQDs plays an important role in the enhancement of the OSCs. Finite-difference time-domain simulations indicate increased electric field intensity due to a small degree of AuQDs aggregation.