Low-temperature synthesis of Bi₂Se₃ thin film semiconductor thermoelectric materials is prepared by the plasma-enhanced chemical vapor deposition method. The Bi₂Se₃ film demonstrated excellent crystallinity due to the Se-rich environment. Experimental results show that the prepared Bi₂Se₃ film exhibited 90% higher transparency in the mid-IR region, demonstrating its potential as a functional material in the atmospheric window. Excellent mobility of 2094 cm²/V·s at room temperature is attributed to the n-type conductive properties of the film. Thermoelectrical properties indicate that with the increase in Se vapor, a slight decrease in conductivity of the film is observed at room temperature with an obvious increase in the Seebeck coefficient. In addition, Bi₂Se₃ thin film showed an enhanced power factor of as high as 3.41 μW/cmK². Therefore, plasma-enhanced chemical vapor deposition (PECVD)-grown Bi₂Se₃ films on Al₂O₃ (001) substrates demonstrated promising thermoelectric properties.

Epitaxial n-type infrared transparent conductive Bi₂Se₃ thin film was cultivated by molecular beam epitaxy (MBE) method on Al₂O₃ (001) substrate. The orientation between Bi₂Se₃ and the substrate is Bi₂Se₃(001)//Al₂O₃(1 2¯ 10). Conducting mechanism ensued the small-polaron hopping mechanism, with an activation energy of 34 meV. The film demonstrates conductivity of n-type, and the resistivity is 7 × 10⁻⁴ Ωcm at room temperature. The Film exhibits an excellent carrier mobility of 1,015 cm²/Vs at room temperature and retains optical transparency in the near-infrared (>70%) and far-infrared (>85%) ranges. To the best of our knowledge, the Bi₂Se₃ film yields the best result in the realm of n-type Infrared transparent conductive thin films generated through either physical or chemical methods. To demonstrate the application of such films, we produced N-Bi₂Se₃/P-CuScO₂ heterojunction diode device, the ∼3.3 V threshold voltage of which conformed fairly well with the CuScO₂ bandgap value. The high optical transparency and conductivity of Bi₂Se₃ film make it very promising for optoelectronic applications, where a wide wavelength range from near-infrared to far-infrared is required.

Photons trapped in the form of waveguide (WG) modes associated with the organic–organic interface and in the form of surface plasmon polariton (SPP) modes associated with the metallic electrode–organic interface result in a large energy loss in organic light-emitting devices (OLEDs). Introducing gratings onto the metallic electrode is especially crucial for recovering the power lost to the associated SPP modes. In our research, we demonstrate the efficient outcoupling of SPP modes in TE mode by two-dimensional (2D) grating, which cannot excited in one-dimensional (1D) grating OLED. This causes a 62.5% increase in efficiency from 2D grating OLED than 1D grating OLED. The efficient outcoupling of the WG and SPP modes is verified by the numerical simulation of both the emission spectra and the field distribution.

We demonstrate highly flexible and efficient organic light-emitting devices (OLEDs) using an ultra-smooth NAN anode. A template-stripping process was employed to create an ultra-smooth NAN anode on a photopolymer substrate. The flexible OLEDs obtained by this method maintained good electroluminescent properties and mechanical stability after bending. The efficiency of the flexible OLEDs was improved by 30.6% compared with conventional OLEDs deposited on PET/ITO substrate due to the enhanced hole injection from the ultra-smooth anode.

A substrate with microstructure can increase the light extraction efficiency of OLEDs. However, the present preparation methods for micro- and nanostructures are not suited for broad-area manufacturing. In this research, we suggested an electrochemical etching approach to patterning Si substrates and effectively generated a vast area of micro-/nanostructures on the surface of Si. We created OLEDs using this patterned substrate. It was discovered through this study that when the current density is 100 mA/cm², the brightness increases by 1.67 times and the efficiency increases by 1.43 times, over a planar equivalent. In the future, this electrochemical etching process for patterned silicon substrates might give rise to a new approach to the large-scale manufacture of microstructured silicon substrates.