Using a color-tunable organic light-emitting diode (CT-OLED) can accord with the circadian cycle of humans and realize healthy lighting. The variation range of the correlated color temperature (CCT) is an important parameter to measure the performance of CT-OLEDs. In this paper, the effect of changing the utilization of phosphorescent materials and the position of the recombination zone (RZ) in the device are investigated by changing the thickness of the emissive layer (EML) and the doping ratio of the host and guest materials. The results show that reducing the red phosphorescent material and improving the blue phosphorescent material can affect the change direction of CCT, but it is not enough to expand the span of CCT (ΔCCT). It is more conducive to improving ΔCCT by more reasonable regulation of the position of the main RZ in EML and the energy transfer from the blue sub-EML to the red sub-EML. Device D obtains the best electro-optic and spectral characteristics, in which the maximum ΔCCT is 5746 K (2661 - 8407 K) as the voltage changes from 3.75 V to 9.75 V, the maximum current efficiency and luminance reach 18.34 cd·A-1 and 12,100 cd·m-2, respectively.
References
[1]
Jeong, C., Park, Y.B. and Guo, L.J. (2021) Tackling Light Trapping in Organic Light-Emitting Diodes by Complete Elimination of Waveguide Modes. Science Advances, 7, eabg0355. https://doi.org/10.1126/sciadv.abg0355
Solanki, A., Awasthi, A., Unni, K.N.N., et al. (2021) An Efficient and Facile Method to Develop Defect-Free OLED Displays. Semiconductor Science and Technology, 36, Article ID: 065005. https://doi.org/10.1088/1361-6641/abf3a8
[4]
Wang, D.X., Hauptmann, J., May, C., et al. (2021) Roll-to-Roll Fabrication of Highly Transparent Ca:Ag Top-Electrode towards Flexible Large-Area OLED Lighting Application. Flexible and Printed Electronics, 6, Article ID: 035001. https://doi.org/10.1088/2058-8585/abf159
[5]
Jung, S.W., Kim, K.S., Park, H.U., et al. (2021) Patternable Semi-Transparent Cathode Using Thermal Evaporation for OLED Display Applications. Advanced Electronic Materials, 7, Article ID: 2001101. https://doi.org/10.1002/aelm.202001101
[6]
Jou, J.H., Shen, S.M., Wu, M.H., et al. (2011) Sunlight-Style Organic Light-Emitting Diodes. Journal of Photonics for Energy, 1, Article ID: 011021. https://doi.org/10.1117/1.3583640
[7]
Mao, M., Lam, T.L., To, W.P., et al. (2021) Stable, High-Efficiency Voltage-Dependent Color-Tunable Organic Light-Emitting Diodes with a Single Tetradentate Platinum(II) Emitter Having Long Operational Lifetime. Advanced Materials, 33, Article ID: 2004873. https://doi.org/10.1002/adma.202004873
[8]
Brainard, G.C., Hanifin, J.P., Warfield, B., et al. (2015) Short-Wavelength Enrichment of Polychromatic Light Enhances Human Melatonin Suppression Potency. Journal of Pineal Research, 58, 352-361. https://doi.org/10.1111/jpi.12221
[9]
Arthur, J.N., Forrestal, D.P., Woodruff, M.A., et al. (2018) Facile and Dynamic Color-Tuning Approach for Organic Light-Emitting Diodes Using Anisotropic Filters. ACS Photonics, 5, 2760-2766. https://doi.org/10.1021/acsphotonics.8b00527
[10]
Yu, J.S. and Zhong, J. (2018) Introduction to OLED Display Technology. Science Press, Beijing, 181-185.
Lee, J., Koh, T.W., Cho, H., et al. (2015) Color Temperature Tuning of White Organic Light-Emitting Diodes via Spatial Control of Micro-Cavity Effects Based on Thin Metal Strips. Organic Electronics, 26, 334-339. https://doi.org/10.1016/j.orgel.2015.08.002
[13]
Zhang, J.H., Song, J.T., Zhang, H., et al. (2016) Sunlight-Like White Organic Light-Emitting Diodes with Inorganic/Organic Nanolaminate Distributed Bragg Reflector (DBR) Anode Microcavity by Using Atomic Layer Deposition. Organic Electronics, 33, 88-94. https://doi.org/10.1016/j.orgel.2016.03.010
[14]
Jiang, J.X., Zheng, W.Y., Chen, J.F., et al. (2020) Color-Tunable Organic Light Emitting Diodes for Deep Blue Emission by Regulating the Optical Micro-Cavity. Molecules, 25, Article 2867. https://doi.org/10.3390/molecules25122867
[15]
Frobel, M., Schwab, T., Kliem, M., et al. (2015) Get It White: Color-Tunable AC/DC OLEDs. Light-Science & Applications, 4, e247. https://doi.org/10.1038/lsa.2015.20
[16]
Joo, C.W., Moon, J., Han, J.H., et al. (2014) Color Temperature Tunable White Organic Light-Emitting Diodes. Organic Electronics, 15, 189-195. https://doi.org/10.1016/j.orgel.2013.10.005
[17]
Lee, H., Cho, H., Byun, C.W., et al. (2018) Color-Tunable Organic Light-Emitting Diodes with Vertically Stacked Blue, Green, and Red Colors for Lighting and Display Applications. Optics Express, 26, 18351-18361. https://doi.org/10.1364/OE.26.018351
[18]
Jeon, Y., Noh, I., Seo, Y.C., et al. (2020) Parallel-Stacked Flexible Organic Light-Emitting Diodes for Wearable Photodynamic Therapeutics and Color-Tunable Optoelectronics. ACS Nano, 14, 15688-15699. https://doi.org/10.1021/acsnano.0c06649
Ying, S., Wu, Y.B., Sun, Q., et al. (2019) High Efficiency Color-Tunable Organic Light-Emitting Diodes with Ultra-Thin Emissive Layers in Blue Phosphor Doped Exciplex. Applied Physics Letters, 114, Article ID: 033501. https://doi.org/10.1063/1.5082011
[23]
Hung, W.Y., Fang, G.C., Lin, S.W., et al. (2014) The First Tandem, All-Exciplex-Based WOLED. Scientific Reports, 4, Article No. 5161. https://doi.org/10.1038/srep05161
[24]
Lee, J.H., Cheng, S.H., Yoo, S.J., et al. (2015) An Exciplex Forming Host for Highly Efficient Blue Organic Light Emitting Diodes with Low Driving Voltage. Advanced Functional Materials, 25, 361-366. https://doi.org/10.1002/adfm.201402707
[25]
Tsuboi, T., Liu, S.W., Wu, M.F., et al. (2009) Spectroscopic and Electrical Characteristics of Highly Efficient Tetraphenylsilane-Carbazole Organic Compound as Host Material for Blue Organic Light Emitting Diodes. Organic Electronics, 10, 1372-1377. https://doi.org/10.1016/j.orgel.2009.07.020
