Perovskite light-emitting diodes (PeLEDs), owing to their unique photoelectric performance, show promising prospects in display applications. Red, green, and blue monochromatic PeLEDs have achieved remarkable breakthroughs, but the study of red/green/blue perovskite co-electroluminescence is still delayed. This study proposed a strategy that an intermediate connection layer (ICL) with hole/electron generation and transport capability is introduced between perovskites. On the one hand, introduction of the ICL can inhibit ion exchange and energy transfer. On the other hand, ICL has a charge-generation function that ensures different perovskite centers capture enough carriers. Furthermore, the thickness of the hole transport layer (NPB) is optimized. Furthermore, the thickness of the hole transport layer (NPB) is regulated, the blue/green tandem PeLED achieved relatively balanced luminescence and exhibits the largest EQE of 0.33%. The developed red/green/blue tandem PeLED exhibits the highest EQE of 0.5%, which is the first report in the field of PeLEDs, and exhibits the largest External Quantum Efficiency(EQE) of 0.33%. The developed red/green/blue tandem PeLED exhibits the highest EQE of 0.5%. In conclusion, this work provides a reference strategy for the co-electroluminescence of multicolor perovskites, which is expected to promote the development of perovskite in display applications.

Solar thermal radiant energy is abundant in storage and pollution-free, and is one of the most competitive clean energies in the future. In recent years, halide perovskite quantum dots (PQDs) are widely used in solar cells and luminescent concentrator solar cells due to their excellent photoelectric properties and unique advantages such as quantum confinement effect and solution processing, and possess vast application prospects, but they are still facing many challenges in future commercial applications. In this review, optimization strategies for improving cell performance are emphatically summarized combined with the domestic and foreign research progress in the field of PQD solar cells. The application of PQDs in luminescent concentrator cells is introduced. Finally, the current challenges in this field are elaborated, and its development trends are prospected. This review provides some ideas for the design and development of the photovoltaic technology in the future.

Preparation of silver selenide (Ag₂Se) based thin films is significant to the micro devices. However, most of reported methods for preparing Ag₂Se films have not achieved the accuracy control and flexible pattern design of films. Inkjet printing technology is believed to provide a valid approach to solve this problem by which combination Ag₂Se and inkjet printing technology shows high value and importance. In this work, Ag₂Se nanoparticles were synthesized by solvothermal method and then dispensed into different solvents to obtain the ink with high stability. Jetting parameters were further developed to achieve the jetting of Ag₂Se ink and optimize the morphology of droplets. Ag₂Se thin films were prepared on polyimide substrates via inkjet printing with different printing layers. As-printed films were finally annealed to increase the crystalline and density. The phase and surface morphology of Ag₂Se films were characterized and the electrical conductivity of the films was measured by using four-probe measurement. Ag₂Se films can achieve higher density and crystallinity with ink concentration and printing layers increasing, which leads to higher electrical conductivity. Improvement of structure and performance of Ag₂Se films result from the increasing deposition and stacking density of Ag₂Se nanoparticles. The electrical conductivity of inkjet-printed Ag₂Se film can reach as high as 399 S·cm^-1 at the ink concentration of 5 mg·mL^-1 and the number of printing layers of 40, which provides a new orientation to prepare Ag₂Se based films and devices.

Black phosphorus (BP) with excellent and unique physical and chemical properties has emerged as the most promising semiconductor for energy storage and conversion, micro-nano devices, photo- and electro-catalysis, biomedicine, and so on. It is crucial to synthesize high-quality precursors of orthorhombic BP for realizing the applications of two-dimensional BP and zero-dimensional BP quantum dots. Herein, the effects of mineralizer components and ratios on BP growth were studied by the chemical vapor transport (CVT) method without temperature gradient. The results indicate that orthorhombic BP can be synthesized under some experimental combinations that can be considered viable only when tin (or lead) and iodine coexist together with the appropriate ratio. And the mass ratio ranges of tin and iodine w(Sn/I₂) for BP preparation is wide, and the size of BP crystal obtained at w(Sn/I₂)=0.47 is up to 1.2 cm, of which yield and crystal quality are superior. Combined with the nucleation and growth mechanism of BP, tin and iodine are severely significant for the nucleation and growth of BP, which has been widely accepted. Mineralization effect of iodine is more obvious than that of tin, and sufficient tin contributes to the synthesis of large-size bulk BP crystals without temperature gradient. As a result, w(Sn/I₂)=0.47 is the optimal minera lizer ratia for fabricating orthorhombic BP in this work.

Metal sulfide Ag₂S is an attractive semiconductor due to its excellent physical and chemical property that enable it with wide applications in fields of catalysis, sensing, optoelectronics in past years. In present work, ϕ18 mm× 50 mm Ag₂S ingot was successfully prepared using zone melting method and its thermoelectric (TE) behavior was investigated. Ag₂S has standard monoclinic P2₁/c space group (α-Ag₂S phase) below 450 K and transfer to cubic structure (β-Ag₂S phase) over this temperature. Ag₂S is a n-type semiconductor as the Seebeck coefficient S is always negative due to the Ag interstitial ions in the material that can provide additional electrons. S is about -1200 µV·K^-1near room temperature, declines to -680 µV·K ^-1 at 440 K and finally decreases to ~-100 µV·K ^-1at β-Ag₂S state. The electrical conductivity (σ) of α-Ag₂S is almost zero. However, the value sharply jumps to ~40000.5 S·m ^-1 as the material just changes to β-Ag₂S at 450 K and then gradually deceases to 33256.2 S·m ^-1 at 650 K. Hall measurement demonstrates that carrier concentration n_H of Ag₂S is suddenly increased from the level of ~10 ¹⁷ cm^-3 to ~10¹⁸ cm^-3during phase transition. Total thermal conductivity κ of α-Ag₂S is ~0.20 W·m ^-1·K^-1 but is ~0.45 W·m^-1·K^-1of β-Ag₂S. Ultimately, a maximum ZT=0.57 is achieved around 580 K that means Ag₂S might be a promising middle-temperature TE material.