Inorganic perovskite quantum dots (QDs) have natural advantages in the field of light-emitting diodes (LEDs) because of their high color purity and tunability in a wide range. However, when manufacturing efficiently mixedanion perovskite QDs (CsPbBr x I 3−x ) to meet the requirements of the pure red color standard in the display field (≈630 nm), results are difficult to control accurately due to the lack of exploration of its microscopic mechanism. Here, a microdynamics model is constructed for anion exchange dominated by vacancies which revealed the key role of polar solvent in reducing the surface energy barrier of anions through first-principle calculations. Besides, a polar solvent construct in situ anion exchange channels method is proposed. Then, the precise control of anion exchange is demonstrated, and the precise regulation spectrum of the whole red-light range (600-680 nm) is achieved. Finally, various QD LEDs (QLEDs) based on these tunable QDs are fabricated and exhibit excellent photoelectric performance in the main red range (620-680 nm). Among them, the champion QLEDs, have peak external quantum efficiency (EQE) of 16.3% at 633 nm and peak EQE of 18.2% at 646 nm, showing potential in meeting the requirements of display standard.

Recently, double perovskite A2B(I)B′(III)X6 has attracted a huge amount of interest due to its wide application in the field of light detection. However, the biggest limitation in the pursuit of further developments in this area is the narrow detection range and the low carrier mobility. It is well known that the effective mean to overcome the above shortcomings is changing the B site ions of A2B(I)B′(III)X6 concentration for the double perovskite. In this study, we study the photoelectronic properties included atomic structure, electronic properties and optical properties of Cs2AgxCu1-xInyTb1-yCl6 (x = 0, 0.25, 0.5, 0.75, 1; y = 0, 0.25, 0.5, 0.75, 1) using first-principles methods. Besides, we systematically investigate carrier mobility of Cs2Ag0.75Cu0.25In0.75Tb0.25Cl6. The results demonstrate Cs2Ag0.75Cu0.25In0.75Tb0.25Cl6 is the most excellent photoelectronic performance with the narrow band gap reduced of 0.56 eV, compared with Cs2AgInCl6, broadening the light detection range. Moreover, the hole mobility is increased from 0.001 to 2.81 cm2 v−1 s−1, which promotes the separation of photogenerated carriers and enhance the photoelectron conversion efficiency. Our works demonstrate that the modification of metal concentration will modulate the optoelectronic performance properties of double perovskites, which provides a theoretical basis for the other double perovskites in potential infrared detection application.

Recently, the effect of dimensional control on the optoelectronic performance of two-dimensional (2D)/three-dimensional (3D) single perovskites has been confirmed. However, how the dimensional change affects the photoelectric properties of 2D/3D all-inorganic double perovskites remains unclear. In this study, we present a detailed theoretical research on a comparison between the optoelectronic properties of 3D all-inorganic double perovskite Cs2AgBiBr6 and recently reported 2D all-inorganic double perovskite Cs4AgBiBr8 with Ruddlesden–Popper (RP) structure based on density functional theory calculations. The results demonstrate the charge carrier mobility and absorption coefficients in the visible spectrum of Cs4AgBiBr8 (2D) is poorer than Cs2AgBiBr6 (3D). Moreover, the value of exciton-binding energy for 2D RP all-inorganic double perovskite Cs4AgBiBr8 (720 meV) is 3 times larger than that of 3D all-inorganic double perovskite Cs2AgBiBr6 (240 meV). Our works indicate that Cs4AgBiBr8 (2D) is a promising material for luminescent device, while Cs2AgBiBr6 (3D) may be suitable for photovoltaic applications. This study provides a theoretical guidance for the understanding of 2D RP all-inorganic double perovskite with potential applications in photo-luminescent devices.