Component Engineering in Multinary Alloyed I-III-VI Type Semiconductor Nanocrystals for Photoluminescence and Electroluminescence

Display technologies have been developed in an unprecedented way in the past one hundred years. The evolution of display technologies is remarkable, progressing from the initial cathode ray tube and rear projection technology to the second-generation advancements of plasma and liquid crystal displays. Now, with the ongoing development of light-emitting diodes (LEDs) technology, including organic LEDs (OLEDs) and quantum dot LEDs (QD-LEDs), we are looking forward to a transition toward mini-LED, micro-LED, and nano-LED technologies. This evolution is gradually rendering displays thinner, more convenient, high-definition, highly luminous, and cost-effective. At present, commercially available OLEDs technology is afflicted with drawbacks such as intricate solution processing, difficulties in achieving efficient mass production, and suboptimal stability, limiting its widespread adoption. QD-LEDs serve as a perfect complement to the limitations of OLEDs and demonstrate a large potential for application in the next generation of displays. Quantum dots (QDs) are nanocrystals (NCs) with a size of 1–10 nm. Since the 1980s, researchers have studied and developed these magic tiny particles. At present, Cd-based materials have been extensively studied, resulting in red-, green-, and blue-LEDs devices approaching or surpassing theoretical external quantum efficiency limits. And the lifetime of Cd-based LEDs has reached commercial standards expected for blue-LEDs. However, the intrinsic toxicity of Cd element limits their further development. In the past decades, several Cd-free QDs have been developed and extensively researched, including III-V type InP QDs, perovskite QDs, I-III-VI type QDs, II-VI type ZnSe QDs, carbon dots, and so on. Among these Cd-free QDs, I-III-VI type semiconductor nanocrystals demonstrate remarkable potential due to facile synthesis, large tunable luminescence range, and solution processability. Moreover, owing to its distinctive nonstoichiometric composition, the luminescence peak position can be readily tuned from the blue to near-infrared by means of straightforward component engineering. This Account presents an overview of the I-III-VI type NCs, starting with the photoluminescent properties regulated by component engineering. Interestingly, narrow-band emission can also be realized through component engineering. Then the construction of light-emitting diodes based on these materials is discussed, encompassing wide-band and narrow-band emission. Additionally, interface engineering is adopted for balancing carrier injection to enhance electroluminescent properties. Moreover, taking advantage of the wide-band emission characteristics of I-III-VI type NCs, white LEDs with high color rendering index can be fabricated by incorporating other blue-emitting materials. Finally, the present challenges and prospective solutions are proposed to propel the advancement of I-III-VI type NCs with high expectations.