No abstract

Elaborate engineering of emitting wavelength of green down‐converter in the spectral range of ≈525–535 nm with narrow full‐width at half‐maximum (fwhm < 25 nm) is an essential prerequisite for faithfully reproducing colors in the quantum dot (QD)‐based backlit display. Herein, different from the previous complex synthesis for green films, FAPbBr3 perovskite QDs films are fabricated by a dual‐additive assisted in situ growth strategy. Both C6H5CH2CH2NH3+ and 1,4,7,10,13,16‐hexaoxacyclooctadecane additives are introduced to synergistically tune green emitting (≈525–535 nm) with the narrowest fwhm down to 21 nm and the highest photoluminescence quantum yield (PLQY) up to 99%. Improved nanocomposite film with excellent long‐term stability is used to construct a prototype liquid crystal display (LCD) with a wide color gamut (118% National Television System Committee and 88% Recommendation BT 2020), a high saturation, and a remarkable color rendition. The performance is superior to that of the commercial white‐LED‐based LCD, showing a great potential of the present green film for high‐definition display application in the future.

No abstract

Perovskite nanocrystals (NCs) with intentionally introduced Mn2+/Yb3+ activators enable tunable emissions covering UV‐orange‐NIR spectral range. However, the exact microscopic energy transfer mechanisms in this system remain unknown. Herein, Mn/Yb codoped CsPbCl3 perovskite NCs with triple emissions originated from exciton recombination of host, 3d–3d transition of Mn2+ and 4f–4f transition of Yb3+ are prepared. Femtosecond resolution transient absorption spectra performed on the pristine CsPbCl3, Mn‐doped, Yb‐doped and Mn/Yb codoped samples clarify efficient and simultaneous energy transfer (ET) from excitons to Mn2+ and Yb3+ dopants. It is testified the sensitizations of dopants mainly result from the trapped hole, taking 285 ps for Mn2+ and 17 ps for Yb3+ respectively, which make less trapped hole recombine with de‐localized carriers. Importantly, energy transfer processes from host to Mn2+ and Yb3+ activators emerge as competition, and the ET probability of exciton‐to‐Mn2+ is higher than that of exciton‐to‐Yb3+. Finally, control experiments further prove that tunable Mn2+ orange emission and Yb3+ NIR emission are achievable via elaborate adjustment of the dopant concentrations.