MMCT-induced high-bright yellow light-emitting phosphor Bi3+-activated Ba2YGaO5 used for WLED

Metal To Metal Charge Transfer Induced Efficient Yellow/Far‐Red Luminescence in Na2Ca3(Nb, Ta)2O9:Bi3+ toward the Applications of White‐LEDs and Plant Growth Light

“…They were determined to be 12 533 and 11 792 cm −1 for Nb and Ta analogues, respectively, which is comparable to some well-known MMCT-based phosphors, such as CaTiO 3 :Bi 3+ (11 784 cm −1 ) and Ba 2 YGaO 5 :Bi 3+ (11 535 cm −1 ). [11,15] The low emission energy with respect to the UV excitation together with the large bandwidth of Bi 3+ emission reveal that the luminescence in Na 2 Ca 3 (Nb, Ta) 2 O 9 :Bi 3+ is assigned to the MMCT process. Boutinaud www.advopticalmat.de proposed a semi-empirical model in 2013 to predict the energy position of MMCT states in Bi 3+ -doped oxide compounds.…”

“…[8] However, the broad excitation band of Eu 2+ -doped phosphor lying in blue and green spectral regions causes a serious reabsorption problem between phosphors, subsequently decreasing the luminous efficacy of w-LEDs. [9][10][11] At present, the researches on far-red phosphors for plant cultivation light mainly focus on the Mn 4+ -and Cr 3+ -doped oxides and fluorides; as their typical absorption bands locate in blue spectral region, matching well with the commercial blue LED chips, simultaneously their emission wavelength can be tuned by varying crystal field strength (D q /B). [12] Nevertheless, the use of Mn 4+ and Cr 3+ activated far-red phosphors is still limited by the low absorption efficiency due to the parity forbidden…”

“…[15,16] The luminescent transition from D state to the ground state of Bi 3+ has the charge transfer character, such as large Stokes shift and broad full width at half maximum (FWHM), which has been demonstrated in many materials, such as CaTiO 3 :Bi 3+ (λ em = 540 nm), GdVO 4 :Bi 3+ (λ em = 555 nm), YVO 4 :Bi 3+ (λ em = 566 nm), and Ba 2 YGaO 5 :Bi 3+ (λ em = 587 nm). [11,15,17] Therefore, benefited from the character of large Stokes shift, the MMCT process could be an approach to realize red/far-red luminescence in Bi 3+ related phosphors by selecting appropriate host materials.…”

Enabling narrowband cyan photoluminescence and long-lasting ultraviolet-A persistent luminescence in Bi3+ single-doped Sr3Sc2Ge3O12 phosphors by selective site occupation

“…17,18 The avoidance of spectral overlap between their excitation and emission bands can reduce the efficiency loss and greatly increase the luminous efficiency. 19,20 Moreover, tunable emission wavelength can be precisely realized by varying the host composition and crystal structure. Based on these attributes, Bi 3+ -doped light-emitting materials are considered as the next generation phosphors for white LED applications.…”

Effects of activated Sr 2+ ion content on strong blue‐emitting Ca 2 Sb 2 O 7 materials for high‐quality WLED devices

“…The phosphor‐convert white light‐emitting diodes (pc‐WLEDs) based on rare‐earth (RE)‐activated materials (eg, Y 3 Al 5 O 12 :Ce 3+ , 1 BaMgAl 10 O 17 :Eu 2+ , 2 (Sr,Ba) 3 SiO 5 :Eu 2+ , CaAlSiN 3 :Eu 2+ , 3 Y 2 O 3 :Eu 3+ , 4 and (Ba,Sr) 2 SiO 4 :Eu 2+ commercial phosphors) have been widely used in lighting displays and decoration fields as the fourth‐generation lighting sources in our daily life. The pc‐WLEDs have outstanding characteristics of energy saving, 5 fast response, 6 high luminous efficiency, 7 stable output, 8 long service time, 9 etc with respect to conventional incandescent lamps.…”