access icon openaccess GaN phosphors converted white light-emitting diodes for high luminous efficacy and improved thermal stability

This study analysed GaN nanophosphors based white light-emitting diodes (WLEDs) with ultraviolet (UV) excitation. Graphene quantum dots (GQDs) used as a charge transfer medium to enhance the performance in terms of luminous efficacy and colour quality. The improvement in colour rendering and colour temperature has been observed with the increase in injection current. The luminous efficacy of radiation also gets improved with injection current and maximises up to 255 lm/W at 260 mA along with 90 colour rendering index and 7100 K correlated colour temperature. Mapping of higher surface temperature for GQD-based devices shows a better thermal stability, indicating the good heat dissipation capability of GQDs because of excellent thermal conductivity. Therefore, proposed WLEDs were found more competent with improved thermal quenching of phosphors for rare-earth-free solid-state lighting as compared to the blue chip-excited yellow phosphors.

Inspec keywords: gallium compounds; III-V semiconductors; lighting; graphene devices; graphene; wide band gap semiconductors; light emitting diodes; phosphors; thermal stability; thermal conductivity; quantum dots; quenching (thermal)

Other keywords: colour rendering index; thermal stability; colour quality; temperature 7100.0 K; graphene quantum dots; thermal quenching; correlated colour temperature; injection current; heat dissipation capability; GQD-based devices; blue chip-excited yellow phosphors; white light-emitting diodes; current 260.0 mA; rare-earth-free solid-state lighting; ultraviolet excitation; GaN; GaN nanophosphors; surface temperature; thermal conductivity; luminous efficacy; charge transfer medium

Subjects: Light emitting diodes; Fullerene, nanotube and related devices; Phosphors

References

    1. 1)
      • 13. Lin, T.N., Santiago, S.R.M., Yuan, C.T., et al: ‘Enhanced performance of GaN based ultraviolet light emitting diodes by photon recycling using graphene quantum dots’, Sci. Rep., 2017, 7, pp. 7108-17108-9.
    2. 2)
      • 12. Tang, L., Ji, R., Li, X., et al: ‘Deep ultraviolet to near-infrared emission and photoresponse in layered N-doped graphene quantum dots’, ACS Nano, 2014, 8, (6), pp. 63126320.
    3. 3)
      • 4. Kumar, M., Dubey, S., Rajendar, V., et al: ‘Fabrication of ZnO thin films by sol–gel spin coating and their UV and white-light emission properties’, J. Electron. Mater., 2017, 46, (10), pp. 60296037.
    4. 4)
      • 1. Chiang, C.-H., Gong, S.-J., Zhan, T.-S., et al: ‘White light-emitting diodes with high color rendering index and tunable color temperature fabricated using separated phosphor layer structure’, IEEE Electron Device Lett., 2016, 37, (7), pp. 898901.
    5. 5)
      • 9. Kumar, M., Kumar, A., Sunny, , et al: ‘Single-crystalline ZnO/graphene quantum dots phosphors-converted white light-emitting diodes’, IEEE Photonics Technol. Lett., 2019, 31, (3), pp. 203205.
    6. 6)
      • 8. Shi, H., Zhu, C., Huang, J., et al: ‘Luminescence properties of YAG:Ce,Gd phosphors synthesized under vacuum condition and their white LED performances’, Opt. Mater. Express, 2014, 4, (4), pp. 649655.
    7. 7)
      • 2. Dai, W., Lei, Y., Xu, M., et al: ‘Rare-earth free self-activated graphene quantum dots and copper-cysteamine phosphors for enhanced white light-emitting-diodes under single excitation’, Sci. Rep., 2017, 7, pp. 12872-112872-11.
    8. 8)
      • 7. Kumar, M., Kumar, A., Makki, A. H., et al: ‘Quantum dot scaffold phosphors: maximizing luminescence quantum yield via different stock environments’, Mater. Lett., 2020, 259, pp. 126846-1126846-4.
    9. 9)
      • 3. Kumar, M., Singh, V.P., Dubey, S., et al: ‘GAN nanophosphors for white-light applications’, Opt. Mater., 2018, 75, pp. 6167.
    10. 10)
      • 11. Damilano, B., Grandjean, N., Semond, F., et al: ‘From visible to white light emission by GaN quantum dots on Si(111) substrate’, Appl. Phys. Lett., 1999, 75, pp. 962964.
    11. 11)
      • 14. Song, Y. H., Han, G. S., Ji, E. K., et al: ‘The novel design of a remote phosphor ceramic plate for white light generation in high power LEDs’, J. Mater. Chem. C, 2015, 3, pp. 61486152.
    12. 12)
      • 10. Nyk, M., Kudrawiec, R., Strek, W., et al: ‘Synthesis and optical properties of Eu3+ and Tb3+ doped GaN nanocrystallite powders’, Opt. Mater., 2006, 28, pp. 767770.
    13. 13)
      • 6. Talele, K., Patil, D. S.: ‘Computation of optical field intensity in nitride based superlattice nanostructures for temperature range (300–370 K)’, Optoelectron. Adv. Mater. Rapid Commun., 2008, 2, (7), pp. 418423.
    14. 14)
      • 5. Sonawane, U. S., Samuel, E.P., Kasar, C. K., et al: ‘Nanosimulation of electron confinement in cerium dopedzinc oxide nanowire structure for light emitting devices’, Optik, 2016, 127, pp. 49374940.
http://iet.metastore.ingenta.com/content/journals/10.1049/iet-opt.2019.0084
Loading

Related content

content/journals/10.1049/iet-opt.2019.0084
pub_keyword,iet_inspecKeyword,pub_concept
6
6
Loading