CsPbX3 (X = Cl/Br, Br, Br/I, I) quantum dots and copper ions co-doped boro-germanate glasses for long wavelength pass filters

We have investigated CsPbX3 (X = Cl/Br, Br, Br/I, I) quantum dots (QDs) co-doped with various metal ions in boro-germanate glass matrix for long wavelength pass filters. Transmittance, optical density (OD), photoluminescence (PL), PL excitation and PL decay have been evaluated. The working wavelength of filters has been extended to wide range from blue 475 nm to dark red 680 nm. Among these metal ions, only Cu2+ ions have obvious quenching or enhancement effect on the PL intensity and lifetime. Small amount Cu2+ of 0.005-0.3 mol % is used for PL quenching and maintaining excellent transmittance and optical density. Trace amounts of Cu2+ ions (<= 0.01 mol.%) have obvious effect. The ratios of I0/I and tau 0/tau are used to evaluate the quenching type and mechanism. The quenching/enhancement effect is different for different CsPbX3 (X = Cl/Br, Br, Br/I, I) QDs glasses (QDGs), showing strong correlation with the anionic composition (i.e. the bandgap) of CsPbX3 QDs. As Cu2+ concentration increases, the PL intensity is quenched for CsPb(Cl/Br)3 (Cl/Br=4:1, 2:1, 1:1), CsPbBr3 and CsPb(Br/I)3 (Br/I=1:1, 1:2, 1:4) QDGs, whereas it is enhanced for CsPbI3 QDG. The PL lifetime is decreased for CsPb(Cl/Br)3 (Cl/Br=4:1, 2:1, 1:1), CsPbBr3 and CsPb(Br/I)3 (Br/I=1:1) QDGs, whereas it is increased for CsPb (Br/I)3 (Br/I=1:2, 1:4) and CsPbI3 QDGs. An energy-dependent electron transfer (ET) mechanism is proposed to explain the quenching/enhancement. The ET and backward ET result in the quenching/enhancement in PL intensity and lifetime. The optical density (OD), absorption edge, transmittance, and transition wavelength have been evaluated for filter performance. The fabricated CsPbX3 (X = Cl/Br, Br, Br/I, I) QDGs can largely meet requirements for the long wavelength pass filters.