CsPb(Br/Cl)3 Perovskite Nanocrystals with Bright Blue Emission Synergistically Modified by Calcium Halide and Ammonium Ion

Abstract

Colloidal cesium lead halide (CsPbX3, X = Cl, Br, and I) perovskite nanocrystals (NCs) demonstrate supreme optical properties in the spectra region of infrared, red, and green. High-performance blue-emitting counterparts are still eagerly required for next-generation full-color displays. However, it is challenging to obtain efficient blue perovskite NCs, especially in a deep blue region with an emission wavelength of around 460 nm or shorter. Herein, calcium halide and ammonium ions are applied simultaneously to modify the CsPb(Br/Cl)3 NCs in situ to reduce surface defects, finally remarkably enhancing the photoluminescence quantum yield (PLQY) from 13% to 93% with an emission peak at 455 nm and the Commission Internationale de l’Eclairage (CIE) coordinates at (0.147, 0.030), which is close to the requirement of the Rec.2020 standard and also meets the requirement of blue emission in DCI-P3. Bright white emission and a wide color gamut are also achieved by combining the commercial red-emitting and green-emitting phosphors. The combination of time-resolved PL spectra and femtosecond transient absorption results discloses the reason for PLQY improvement as suppressing the nonradiative recombination.

Enhancing Photoluminescence of CsPb(ClxBr1−x)3 Perovskite Nanocrystals by Fe2+ Doping

“…The incorporation of appropriate impurity ions into host lattices has been exploited as a promising method to stabilize the crystallographic phases while modulating the optical, electronic, and magnetic properties of diverse semiconductors [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Regarding the halide perovskites, the partial substitution of Pb 2+ by divalent metal ions, such as Cu 2+ , Mg 2+ , Fe 2+ , Co 2+ , Ni 2+ , and Mn 2+ at the B sites of the perovskite lattice have been demonstrated [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Klug et al revealed that the perovskite films retain an excellent photovoltaic performance if less than 3% Pb 2+ ions are substituted by homovalent metal species due to the high tolerance of the perovskite lattices [ 31 ].…”

Suppressing Growth Strategy on Synthesizing Stable and High-Quality Blue-Emitting CsPbBr3 Quantum Dots

“…12,13 Among them, the efficiency improvement of blue perovskite LEDs (PeLEDs) based on CsPbBr 3 is still inferior to that of their green and red counterparts. 14 The current approaches to achieve deep-blue emission are doping 15 and the Br/Cl mixed anion replacement 16,17 strategy. However, the devices usually have low device efficiency, short lifetime, and instability due to phase separation and ion migration.…”

“…Therefore, the CsPbBr 3 nanostructures are extensively applied in solar cells, light-emitting diodes (LEDs), photodetectors, and other photovoltaic fields. , Among them, the efficiency improvement of blue perovskite LEDs (PeLEDs) based on CsPbBr 3 is still inferior to that of their green and red counterparts . The current approaches to achieve deep-blue emission are doping and the Br/Cl mixed anion replacement , strategy. However, the devices usually have low device efficiency, short lifetime, and instability due to phase separation and ion migration. − In addition, ultra-small CsPbBr 3 quantum dots (QDs) with strong confinement can also achieve blue PeLEDs. , …”

Optimizing the Synthetic Conditions of “Green” Colloidal AgBiS2 Nanocrystals Using a Low-Cost Sulfur Source

“…Colloidal AgBiS 2 nanocrystal (NC), a member of the I–V–VI 2 ternary semiconductor materials [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], is a promising eco–friendly material for solar cells owing to colloidal AgBiS 2 NC having a wide absorption spectrum in the visible to near–infrared region (300–1600 nm) [ 8 , 9 , 10 ], high absorption coefficient (~10 5 cm −1 ) [ 1 , 11 , 12 , 13 ], and good air stability [ 8 ]. The hot injection method is widely used to prepare high quality NCs such as PbS [ 14 ], PbSe [ 15 , 16 ], and halide perovskite NCs [ 17 , 18 , 19 , 20 , 21 , 22 ]. In 2016, Bernechea et al synthesized colloidal AgBiS 2 NCs by the hot injection method using hexamethyldisilathiane (TMS) as the sulfur source and first reported colloidal AgBiS 2 NC–based solar cells with a certified power conversion efficiency (PCE) of 6.3% [ 1 ].…”