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- 저자 : Vivek Vishal Sharma (검색결과 2 건)
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M. Manhas,Vinay Kumar,Vivek K. Singh,J. Sharma,Ram Prakash,Vishal Sharma,A.K. Bedyal,H.C. Swart 한국물리학회 2017 Current Applied Physics Vol.17 No.11
The present paper reports on the structural and luminescent properties of un-doped and Sm3þ doped Ba2Ca(BO3)2 phosphors synthesized by the conventional solid state method. For structural characterizations, the X-ray diffraction, FTIR spectroscopy and Rietveld refinement method were used. The FTIR spectrum was composed of basic BO3 and BO4 structural units of borates. The Sm3þ doped phosphors under 402 nm (6H5/2/4L13/2) excitation, showed an orange red emission corresponding to the 601 nm (4G5/2 / 6H7/2) transition of the Sm3þ ion. An increase in the PL emission intensity was observed up to 2 mol % with the increase in Sm3þ ions concentration. The critical distance between the Sm3þ e Sm3þ ions were found to be 24.36 Å. Moreover, the phosphors decaytime and optical bandgap at different concentration of Sm3þ ion also have been discussed in details. All the results show that Ba2Ca(BO3)2:Sm3þ phosphor may be used with a near ultraviolet (n-UV) chip to fill the amber gap in light emitting diodes (LEDs).
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신광용,윤동환,하영우,정윤혜,조영채,백승민,신혜선,Vivek Vishal Sharma,김기환 한국전기전자재료학회 2024 Transactions on Electrical and Electronic Material Vol.25 No.1
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) stands as a prominent hole transport layer (HTL) in perovskite light-emitting diodes (LEDs), known for its remarkable electrical conductivity and light transmittance. However, its electron-blocking properties have shown limitations in achieving optimal charge balance by allowing excessive electron transport. To overcome this challenge, we introduce poly(triarylamine) (PTAA) as an intermediate HTL material between the PEDOT:PSS layer and the perovskite emission layer. By leveraging PTAA's higher lowest unoccupied molecular orbital (LUMO) level of 1.8 eV compared to PEDOT:PSS, a substantial energy barrier is established. This energy barrier effectively traps electrons within the emission layer, elevating radiative recombination rates and consequently enhancing overall efficiency. The notable LUMO energy gap of approximately 1.7 eV between PTAA and CsPbBr 3 further contributes to efficient electron confinement. To optimize hole injection and promote charge balance, we address the highest occupied molecular orbital (HOMO) level mismatch between PEDOT:PSS and PTAA. This is achieved by incorporating perfluorinated ionomer (PFI) into PEDOT:PSS, inducing a band bending effect. The resulting energy level alignment leads to improved device performance. Experimental validation of this energy level engineering strategy in light-emitting diodes (LEDs) demonstrates substantial enhancements. The external quantum efficiency (EQE) achieves a remarkable 2.8-fold increase, advancing from 1.07% to 2.81%, when compared to devices employing PEDOT:PSS alone. Moreover, the current effi ciency (CE) experiences a 2.5-fold augmentation, surging from 3.74 cd/A to 9.35 cd/A. The luminance levels soar by an impressive 11.3-fold, ascending from 1,745 cd/m2 to an impressive 19,780 cd/m2 .
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