Publication date: 22nd July 2026
Perovskite-based full-colour display technologies remain challenging due to the slower development of stable and efficient blue-emitting perovskites compared to their red and green counterparts. While compositional engineering can induce blue shifts, it often compromises stability, promotes ion migration, and increases defect sensitivity [1]. Multiple quantum wells (MQWs) offer an alternative design strategy in which emission can be tuned through structural confinement and interfacial electronic effects rather than relying solely on chemical modification [2].
In this work, we combine density functional theory (DFT) calculations with experimental characterization to investigate the effects of Rb+ substitution and quantum confinement in CsPbBr3/TPBi MQW heterostructures. Experimental results show that reducing the well thickness and increasing the Rb content progressively widen the bandgap, shifting the emission from the green region near 520 nm in bulk CsPbBr3 to the blue region near 490 nm in 3 nm Rb0.37Cs0.63PbBr3 wells, in agreement with the DFT calculations. DFT further reveals that Rb substitution has only a minor influence on the TPBi interface, with interfacial charge transfer remaining on the order of 10-2 e and band bending limited to the meV scale, while also preserving the type-I band alignment favourable for radiative recombination. At the same time, Rb incorporation induces local lattice distortions and electronic perturbations that reduce the transition dipole strength, consistent with the observed suppression of photoluminescence. These adverse effects can be mitigated within the MQW architecture, where stronger confinement and increased well-barrier periodicity help recover emission intensity.
Overall, this combined experimental and DFT study establishes cation-doped MQW heterostructures as a promising platform for blue emission in halide perovskites. By enabling tunability via well thickness, layer number, and composition, these findings provide design principles for developing stable and efficient blue perovskite light emitters for future optoelectronic applications.
This work is supported by the the National Research Foundation (NRF) Singapore under its Competitive Research Programme. The computational part of this work was fully performed on resources of the National Supercomputing Centre, Singapore (https://www.nscc.sg).
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