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Organic light‐emitting transistors (OLET) evolved from the fusion of the switching functionality of field‐effect transistors (FET) with the light‐emitting characteristics of organic light‐emitting diode (OLED) that can simplify the active‐matrix pixel device architecture and hence offer a promising pathway for future flat panel and flexible display technology. This review systematically analyzes the key device/molecular engineering tactics that assist in improving the electrode edge narrow emission to wide‐area emission for display applications via three different topics, that is, narrow to wide‐area emission, vertical architecture, and impact of high‐κ dielectric on the device performance. Source–drain electrode engineering such as symmetric/asymmetric, planar/non‐planar arrangement, semitransparent nature, multilayer approach comprising charge transport, and work function modification layers enable widening the emission zone. Vertical OLET architecture offers short channel lengths with a high aperture ratio, pixel type area emission, and stable light‐emitting area. Transistors utilizing high‐κ dielectric materials have assisted in lowering the operating voltage, enhancing luminance and air stability. The promising development in achieving wide‐area emission provides a solid basis for constructing OLET research toward display applications; however, it relies on developing highly luminescent and fast charge transporting materials, suitable semitransparent source/drain electrodes, high‐κ ‐dielectrics, and device architectural engineering. [ABSTRACT FROM AUTHOR]

Transparent single Dy3+, Sm3+, and Dy3+/Sm3+ co-activated tungstate-tellurite (TWKZBi) glass matrices were synthesized via melt-quenching process. The optical features of the prepared glass matrices were examined with the aid of the absorption spectra. Under various excitation wavelengths (366, 388 and 454 nm), Dy3+ doped TWKZBi (TWKZBiDy) glasses revealed a prevailing emission peak ⁓575 nm related to the yellow band (4F 9/2 → 6H 13/2) transition, while Sm3+ doped TWKZBi (TWKZBiSm) glass matrices reveal strong intense emission peak at ∼600 nm associated with the orange-red band (4G 5/2 → 6H 7/2) transition. The emission intensity progressively surges with an increment in Sm3+ ion content (up to 1.5 mol%), confirming the ET mechanism between Dy3+ and Sm3+ ions. Application of Dexter's ET formulation with the Reisfeld's approximation revealed that the ET mechanism involves a non-radiative dipole-dipole (d-d) interaction between Dy3+ and Sm3+ ions. The average lifetime (τ a v g) values for the 4F 9/2 state of Dy3+ ions in the TWKZBiDySm glass sample was measured and found that these values decreased with increasing Sm3+ ion content. In addition, the ET efficiencies (η D y → S m) of the TWKZBiDySm glass matrices were evaluated using the lifetime curves. The color coordinates (x , y) and the correlated color temperature (CCT) values of the co-activated glass samples were estimated. Based on the chromaticity coordinates and CCT values, it was found that the desired color of the TWKZBiDySm glass samples can be modulated from warm white light to orange-red light via precisely adjusting the concentration of Sm3+ ions and at selected excitation wavelengths. Furthermore, the emission intensity observed at 373 K was 83.83 % compared to the emission intensity at ambient temperature, indicating the excellent thermal stability of the TWKZBiDySm glasses prepared. The above results confirm that the prepared Dy3+/Sm3+ co-activated TWKZBi glass matrix can be a promising candidate for white light and other photonic devices. Transparent single Dy3+, Sm3+, and Dy3+/Sm3+ co-activated tungstate-tellurite (TWKZBi) glass matrices were synthesized via the melt-quenching process. The PL spectra were studied at selected excitation wavelengths to examine the energy transfer process in the present Dy3+/Sm3+ co-activated TWKZBi glass via altering the concentration of Sm3+ ions. The emission profiles with varying temperatures from RT to 448 K indicate the good thermal stability of the prepared TWKZBiDySm glasses. Therefore, the prominent results confirm that the prepared TWKZBiDySm glasses will be beneficial for white light and other fascinating photonic applications. [Display omitted] • Dy3+/Sm3+ co-activated tungstate-tellurite (TWKZBiDySm) glasses synthesized. • Emitting color can be tuned from warm white to orange-red with dopant concentration. • Energy transfer from Dy3+ to Sm3+ ions confirmed via theoretical models. • TWKZBiDySm glasses exhibit excellent thermal stability with high activation energy. • Optimized glass could be a potential candidate for w-LEDs and photonic devices. [ABSTRACT FROM AUTHOR]