Nat. Commun.: Two color orthogonal polarized organic light-emitting diode

In recent years, linearly polarized organic light-emitting diodes have greatly enriched the application scenarios of polarization optics and optoelectronics industries. The low-cost and large-area preparation of linearly polarized organic light-emitting diodes with high polarization, strong directional emission, narrow bandwidth, and multi-color adjustability is an important challenge in the current field, targeting 3D display, augmented reality/virtual reality, high-density data storage, and optical encryption.

Recently, a team led by Professor Liang Ningning and Professor Zhai Tianrui from Beijing Institute of Technology proposed a high-performance dual color orthogonal polarized organic light-emitting diode based on laser dual beam interference lithography and vacuum thermal evaporation method. This method successfully obtained a large-area dielectric/metal nano one-dimensional grating of 3 × 3 cm2. Through precise theoretical simulation and device design optimization, the orthogonal emission of high-intensity sky blue light transverse electric mode waveguide mode and green transverse magnetic mode waveguide mode of organic light-emitting diodes was achieved. Its excellent polarization extinction ratio has met commercial requirements; An organic light-emitting diode with dual color orthogonal polarization emission that combines high polarization extinction ratio, high external quantum efficiency, and directional emission has been achieved. The related achievements were published in the journal Nature Communications under the title "Dual color emissive OLED with orthogonal polarization modes".

To ensure the conductivity and transparency of the metal electrodes, researchers effectively determined the types and thicknesses of dielectrics and metal electrodes using the finite difference time domain method. A 100 nm MgF2 (100 nm)/25-nm Ag one-dimensional grating electrode with a period of 300 nm, a groove depth of 80 nm, and a size of 3 × 3cm2 was successfully prepared using laser dual beam interference lithography and vacuum thermal evaporation method, as shown in Figure 1. This work abandons the weak microcavity effect caused by the traditional OLED using transparent ITO as the anode, and forms a Fabry Perot microcavity by introducing a bimetallic electrode with high reflectivity; Combining the finite difference time domain method to achieve the maximum localization of the transverse polarization waveguide mode at a wavelength of 470 nm, as shown in Figures 2a-h. By introducing a one-dimensional grating, the Fabry Perot microcavity is effectively coupled with the grating microcavity to form different responses to transverse electric and transverse magnetic polarization waveguide modes, achieving strong 470 nm wavelength TE light and suppressed 500 nm wavelength TM light orthogonally polarized light emission, as shown in Figure 2i-o. The coupling theory of the coupling cavity is determined.

Figure 1. Design concept and specific preparation process diagram of dielectric/metal nanograting structure.

Figure 2. Simulation results of optical properties of planar OLED and corrugated OLED.

This work achieved the emission of horizontally polarized sky blue light with vertical emission, which has a polarization extinction ratio of 15.8 dB, a suppressed full width at half height of 28 nm, and a small angle emission of ± 30 °. At the same time, it achieved the emission of horizontally polarized green light; The proposed design concept can be extended to full color gamut linear polarization modulation with high extinction ratio and excellent external quantum efficiency, providing a powerful platform for manufacturing low-cost, large-area, and multi polarization multi-color luminescent LP-OLED for 3D display, augmented reality/virtual reality, high-density data storage, and optical encryption. Beijing University of Technology is the sole author of this paper, with Chen Ruixiang, a doctoral student from the School of Physics and Optoelectronic Engineering, as the first author, and Professor Liang Ningning and Professor Zhai Tianrui as co corresponding authors. This study was supported by the National Natural Science Foundation of China.

Figure 3. Performance results of planar OLED and corrugated OLED devices.

Figure 4. Spatial pattern display and development status of corrugated OLED.

Figure 5. Color image encryption application with coordinated control of polarization and color.

Source: Sohu