Bandgap Engineering of Sr2+/Cl– Co-Doped CsPbBr3 Quantum Dot-Based Glass with Narrow Stokes Shift for Blue-Violet-Excited Color-Conversion Displays

Abstract

CsPbX3 (X = I, Br, Cl) perovskite quantum dots (PQDs) are promising for optoelectronic applications owing to their tunable bandgap, high photoluminescence (PL) quantum yield, and narrow emission bandwidth. However, CsPbBr3 PQDs exhibit a large Stokes shift (>155 nm) and are mainly excited by near-ultraviolet light (∼365 nm), resulting in substantial energy loss and limiting their compatibility with blue light-emitting diodes (LEDs) excitation. Herein, Sr2+/Cl– codoped CsPbBr3 PQDs embedded in zinc borosilicate (ZBS) glass powders were developed to regulate the band structure. Sr2+ incorporation significantly enhances PL performance. Notably, CsPb0.5Sr0.5Br3 PQDs exhibit ∼1.6 times higher PL intensity than undoped samples with a slight red-shift (∼5 nm). Meanwhile, the bandgap of CsPb0.1Sr0.9Br3 PQDs is widened to 3.12 eV compared to 2.36 eV for CsPbBr3. Totally different with undoped PQDs, the excitation peak of CsPb0.1Sr0.9Br3 PQDs covers the desired blue-violet region in the range of 400–480 nm and the maximum peak is located at 414 nm, which displays a narrow Stokes shift of 106 nm. Further, Cl– ions substitution in Sr-doped host materials enables the blueshift of the PL emission from 521 nm (green light) to 448 nm (blue light) via bandgap engineering accompanied by ultranarrow Stokes shift of ∼34 nm for CsPb0.1Sr0.9BrCl2 sample. The Sr-doped PQDs embedded in ZBS glass also demonstrate excellent water resistance, retaining ∼96% of their initial PL intensity after immersion in deionized water for more than 60 days. Thus, the ultrastable PQDs glass powders can be effectively excited by the blue-violet light chip (410 nm-460 nm) via bandgap engineering possess and demonstrate promising application potential in color-conversion display devices, wide-color-gamut backlight systems and screen-printable emissive display films.