Recent progress in liquid crystal devices and materials of TFT-LCDs

Figures & data

Table 1. Physical properties of LC mixtures for TV applications.

Application	HB-FFS	UBplus	UBplus	UBplus
Mixture	A	B	C	D
Clp./°C	80.0	99.0	98.0	95.5
Δn (@589 nm)	0.100	0.093	0.091	0.087
Δε (@1 kHz)	2.7	−3.9	−4.0	−4.0
γ/mPas	65	134	147	149
K11/pN	13.1	18.5	20.8	20.3
K33/pN	14.9	19.3	20.4	20.9
*Kavg/pN	11.5	15.7	17.2	17.1
γ/K11/mPas/pN	5.0	7.2	7.1	7.3

*K_avg = (K₁₁ + K₃₃ + K₁₁/2)/3.

Table 2. Physical properties of LC mixtures for fast response time.

Application	UBplus	UBplus
Mixture	I	J
Clp./°C	99	84
Δn (@589 nm)	0.093	0.093
Δε (@1 kHz)	−3.9	−3.1
γ/mPas	134	81
K11/pN	18.5	15.8
K33/pN	19.3	16.4
γ/K11/mPas/pN	7.2	5.1

Figure 1. Structures of high-end TFT-LCDs with local dimming mini-LEDs and QD films. (a) a homogeneously aligned FFS LC cell with no compensation film, and (b) a thin film containing dichroic dyes on top of a conventional polarizer. Macroscopic photographs comparing dark states surrounding a bright circle image when the dichroic film formed between two glass substrates exists above an uncompensated TV panel for (c) 1 wt% and (d) 2 wt% dye-doped films. Case (d) demonstrates excellent dark states surrounding the bright circle image in all viewing directions [30].

Figure 2. LC molecular responses under different field frequencies (e.g. 60 Hz [left] and 1 Hz [right]). At 1 Hz, geometrical deformation can occur having flexoelectric polarization.

Figure 3. Brightness difference between frames based on flexoelectric effect in an FFS electrode structure [42].

Figure 4. Structural difference and comparison between FFS and IPS modes in which flexoelectric effect exists at low-frequency driving [42].

Figure 5. Flexoelectric polarization of pear and banana-shaped molecules and the contribution of dipoles of -LC (bend) and quadrupoles (splay) to flexoelectric coefficients.

Figure 6. Schematic comparison of pixel structures and simulated transmittance between AFFS and HFFS modes [47].

Figure 7. Comparison of voltage-dependent transmittance curves in high-resolution mobile TFT-LCDs. The HFFS mode shows much-improved transmittance, as also shown in the microscopic image of a pixel [47].

Figure 8. Comparison of pixel structures between (a) IPS-Pro pixel and (b) IPS-Pro Next pixel [48,49].

Figure 9. Comparison of pixels of 47′′ IPS-LCDs [48].

Figure 10. Cross-sectional view of a pixel structure of BOE’s high transmittance ADS mode along data and gate line. The thickness of an organic (ORG) layer is controlled by a full-tone (FT) and half-tone (HT) mask [50].

Figure 11. Evolution of process routes from ADS to i-ADS and high transmittance ADS (HADS) utilizing ORG layer. ADS requires two ITO layers and 1ITO and 2ITO represent first and second layers, respectively [12].

Figure 12. Typical structure of SA-VA additive (e.g. Compound 5) and SA-VA process. After LC filling, the polar (blackhead groups) interact with the substrates and give a vertical orientation. Under the application of a voltage and irradiation by UV light, the tilt is formed and fixed. The RMs polymerize to form a film at the substrate surfaces [57].

Figure 13. Schematic illustration of the fabrication process for the self-alignment FFS-mode LC cell (Self-FFS cell): (a) before preparing the SAL and (b) after preparing the SAL and obtaining the homogeneous alignment, (c) the material design concept of the additive agents, and (d) the monomer-carrying chalcone unit used in this study [59,60].

Figure 14. Simulated transmittance in a pixel of PS-VA mode: (a) Fishbone electrode (pixel) and plane electrode (common), (b) Transmittance profile in different resolution, and comparison of transmittance with LC orientation profile in (c) PS-VA and (d) C-PS-VA mode [65].

Figure 15. (a) Structure of wide-viewing-angle film with representative three optical rays and (b) Comparison of iso-luminance contours [68]. AG indicates anti-glare film.

Figure 16. Structure of blue phase I [72].

Figure 17. Structure of blue phase III [72]

Table 3. Normal mode and blue phase mode [72–74].

Phase	Conventional nematic phase	Polymer-stabilized blue phase
Electro-optic switching	anisotropy to anisotropy	isotropy to anisotropy
Response time	a few ms	tens of µs to sub-ms
Surface treatment	required	free

Figure 18. Polymer-stabilized blue phase I and its world’s prototype were made by Samsung Electronics in the exhibition of the SID 2008 [75,76].

Figure 19. Comparison of polymer-stabilized BPI, isotropic phase, and BPI and the switching property of BPIII [72,73].

Figure 20. BP color tuneable Photonic soft crystals [84].

Figure 21. Molecular structures and modification of ferroelectric LCs in nematic phase [87,103].

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