Stable two-dimensional tin-based perovskites for warm-white light emitters

Two-dimensional (2D) Sn-based organic-inorganic hybrid perovskites are useful materials for white light emitters due to their super high fluorescence efficiency and higher stability when compared to their three-dimensional (3D) counterparts. Herein, 2D Ruddlesden-Popper (RP) perovskites (BA)2Sn(Br1-x Ix)4 (BA = n-butylammonium, x: 0–1) were prepared and regulated using halogen doping. As iodine content increased, the band gap of (BA)2Sn(Br1-xIx)4 was finely regulated from 2.35 eV to 2.0 eV, thereby tuning the photoluminescence from yellow to red with relatively high PLQY exceeding 40 %. The use of small amounts of Pb2+ to stabilize Sn2+ through the addition of PbO in the precursor solution resulted in high air- and photo stable (BA)2Pb0.1Sn0.9(Br–I)4 phosphors with bright yellow to red light. The mixture with (BA)2PbBr4 (blue light phosphor) followed by excitement by UV LED chips (285 nm) resulted in cold and warm white Sn–Br–I perovskite LEDs. The CIE coordinates and correlated color temperature (CCT) indicated Br0.4I0.6 LED as an ideal warm-white emitter with suitable CIE (0.352, 0.330) and CCT (4376.3 K). The prepared white LEDs showed high photo and air stability without significant luminescence decay (<5 % relative) under continuous UV light excitation over 200 min and exposure to air for 3 months.