Removal of Codispersible Residual Impurities from CuInS2/ZnS Quantum Dots for Window-Replaceable Luminescent Solar Concentrators

Luminescent solar concentrators (LSCs) are promising for building-integrated photovoltaic windows. CuInS2/ZnS colloidal quantum dots (CQDs) are ideal LSC emitters owing to broad absorption, large Stokes shift, and high photoluminescence quantum yield (PLQY). However, ZnS shell growth with zinc acetate, 1-dodecanethiol, and oleic acid produces codispersible residual impurities (CDRI) via in situ thioesterification. Identified here for the first time, these species mimic CQD dispersion/precipitation, coprecipitating during excess-antisolvent purification, reducing colloidal stability and limiting ink formulation. We introduce polarity-tuned precipitation that precipitates CQDs while retaining CDRI in the supernatant, preserving PLQY, improving colloidal stability, and expanding formulation compatibility. The resulting inks yield impurity-free, low-haze, uniform 10 × 10 cm2 LSC waveguides and LSC-PV windows with acceptable transmittance. Integrated with heterojunction Si cells and a power-management IC, the window reliably powers a Bluetooth low energy sensor under mixed sunlight and indoor light.