Ultrathin Monolayer Mn2+‐Alloyed 2D Perovskite Colloidal Quantum Wells.

Atomically thin monolayer Mn2+‐alloyed 2D Ruddlesden–Popper (RP) perovskite colloidal quantum wells (CQWs) are demonstrated as efficiently tunable emitter with wide color gamut. Ultrathin character evidenced by the well‐controlled thickness of ≈1.8 nm, leads to alloying rather than doping mechanism reported previously, which facilitates uniform and large‐ratio substitution of Pb2+ by Mn2+ within the metal‐halide octahedra layer. Photoluminescence spectra reveal dual color emissions constituted by blue‐greenish intrinsic excitonic emission and reddish Mn2+ emission with a high photoluminescence quantum yield (PLQY) up to 32%. Two individual channels are created for precisely targeting the emission color in a wide gamut by finely controlling the excitonic emission via the chemical compositions of Br/I and the Mn2+ emission via the chemical compositions of Mn/Pb, respectively. Experimentally, high quality single‐component white emitter ultrathin CQWs are achieved with CIE coordinate value of (0.33, 0.32), 21% PLQY, and good film processibility. The results reveal great potential as applicant for next generation lighting and display technologies. [ABSTRACT FROM AUTHOR]