Formamidinium (FA)-based perovskite materials show an extended absorption spectrum to 840 nm, which enables high power conversion efficiencies of over 20% compared with normal-structure perovskite solar cells (PSCs).

Eco-friendly Sn-based perovskites show significant potential for high-performance second near-infrared window light-emitting diodes (900 nm – 1700 nm). Nevertheless, achieving efficient and stable Sn-based perovskite second near-infrared window light-emitting diodes remains challenging due to the propensity of Sn²⁺ to oxidize, resulting in detrimental Sn⁴⁺-induced defects and compromised device performance. Here, we present a targeted strategy to eliminate Sn⁴⁺-induced defects through moisture-triggered hydrolysis of tin tetrahalide, without degrading Sn²⁺ in the CsSnI₃ film. During the moisture treatment, tin tetrahalide is selectively hydrolyzed to Sn(OH)₄, which provides sustained protection. As a result, we successfully fabricate second near-infrared window light-emitting diodes emitting at 945 nm, achieving a performance breakthrough with an external quantum efficiency of 7.6% and an operational lifetime reaching 82.6 h.

The tunable photoluminescence (PL) of nitrogen-doped carbon dots (NCDs) has attracted much attention in recent years while the specific mechanism is still in dispute. Herein, NCDs with yellow emission were successfully synthesized via a facile hydrothermal approach. Three kinds of post-treatment routes were investigated to verify the influence of surface states on the PL emission of NCDs including solvent-dependent, reduced-reaction and metal-enhanced effect. The interaction mechanism was studied by absorption spectrum, structural characterizations, steady-state and time-resolved spectroscopy. When dispersed in different solvents, the as-prepared NCDs show tunable emission and PL enhancement attributed to hydrogen bonding between solvents and NCDs. Besides, the addition of NaBH4 can induce the reduction of the C=O bonds existing in original NCDs to C–O bonds and thus result in the enhancement of the intrinsic (n–π*) emission. Moreover, metal-enhanced fluorescence of NCDs can also be observed when adding Ag+ into initial NCD solution, which might be ascribed to aggregation-induced emission enhancement. These results for post-treated NCDs demonstrate that surface functional groups are responsible for PL emission and provide new possibilities like multi-image sensing and lighting application.

All-inorganic CsPbX₃ (X = Cl, Br, and I) perovskite quantum dots (QDs), an emerging type of luminescent materials, have drawn extensive attention in recent years. However, the amelioration of their stability is becoming a critical issue. Herein, we present a facile and efficient approach to prepare novel perovskite QDs/metal–organic frameworks (CsPbX₃/ZIF-8) composites under ambient-atmospheric conditions. The obtained composites exhibit better properties including high photoluminescence (PL) quantum yields (QYs) (41.2% for green and 34.8% for red), narrow-band emission (20 nm for green and 31 nm for red), and enhanced stability in comparison to bare QDs. Furthermore, their application in a remote-type white-light-emitting device was explored and a wide color gamut (~137% of the National Television System Committee standard) was achieved, verifying that these novel luminescent composites have great prospect in backlight display application.