Dinuclear Pt­(III) complexes were commonly reported to have short-lived lowest-lying triplet states, resulting in extremely weak or no photo­lumin­escence. To overcome this obstacle, a new series of dinuclear Pt­(III) complexes, named Pt2a-Pt2c, were strategically designed and synthesized using donor (D)–acceptor (A)-type oxadiazole-thiol chelates as bridging ligands. These dinuclear Pt­(III) complexes possess a d7–d7 electronic configuration and exhibit intense phosphorescence under ambient conditions. Among them, Pt2a exhibits orange phosphorescence maximized at 618 nm in degassed dichloromethane solution (Φp ≈ 8.2%, τp ≈ 0.10 μs) and near-infrared (NIR) emission at 749 nm (Φp ≈ 10.1% τp ≈ 0.66 μs) in the crystalline powder and at 704 nm (Φp ≈ 33.1%, τp ≈ 0.34 μs) in the spin-coated neat film. An emission blue-shifted by more than 3343 cm–1 is observed under mechanically ground crystalline Pt2a, affirming intermolecular interactions in the solid states. Time-dependent density functional theory (TD-DFT) discloses the lowest-lying electronic transition of Pt2a-Pt2c complexes to be a bridging ligand–metal–metal charge transfer (LMMCT) transition. The long-lived triplet states of these dinuclear platinum­(III) complexes may find potential use in lighting. Employing Pt2a as an emitter, high-performance organic light-emitting diodes (OLEDs) were fabricated with NIR emission at 716 nm (η = 5.1%), red emission at 614 nm (η = 8.7%), and white-light emission (η = 11.6%) in nondoped, doped (in mCP), and hybrid (in CzACSF) devices, respectively.

The industrialization of quantum dot light-emitting diodes (QLEDs) requires the use of less hazardous cadmium-free quantum dots, among which ZnSe-based blue and InP-based green and red quantum dots have received considerable attention. In comparison, the development of InP-based green QLEDs is lagging behind. Here, we prepare green InP/ZnSe/ZnS quantum dots with a diameter of 8.6 nm. We then modify the InP quantum dot emitting layer by passivation with various alkyl diamines and zinc halides, which decreases electron mobility and enhances hole transport. This, together with optimizing the electron transport layer, leads to green 545 nm InP QLEDs with a maximum quantum efficiency (EQE) of 16.3% and a current efficiency 57.5 cd/A. EQE approaches the theoretical limit of InP quantum dots, with an emission quantum yield of 86%.

The weak fluorescence( quantum yield < 1% in cyclohexane)o fp henothiazine (PTZ)i mpedes its further application. In addition, the nitro group (NO 2 )i sawell-known fluorescence quencher.I nterestingly,w eo btained ah ighly fluorescent chromophore by combining these two moieties, forming 3-nitrophenothiazine (PTZ-NO 2 ). For comparison, a series of PTZ derivatives bearing electron-withdrawing groups (EWGs;C Na nd CHO) or electron-donating groups (EDGs;O Me) at the 3-position have been designed and synthesized. The phenothiazines bearing EWGs exhibited enhanced emission compared with the parent PTZ or EDGd e-rivatives. Computational approaches unveiled thatf or PTZ and PTZ-OMe,t he transitions are from HOMOs dominated by p orbitals to LUMOso fm ixed sulfur nonbonding-p*o rbitals, and hence are partially forbidden. In contrast, the EWGs lower the energy level of the lone-pair electrons on the sulfur atom, thereby suppressing the mixingo ft he nonbondingo rbital with the p*o rbital in the LUMO, such that the allowed pp*t ransition becomes dominant. This work thus demonstrates aj udiciousc hemical design to fine-tune the transition character in PTZ analogues,w ith PTZ-NO 2 attaining 100 %e mission quantumy ields in nonpolar solvent.

Two-dimensional (2D) Dion−Jacobson (DJ) perovskite solar cells (PSCs), despite their advantage in versatility of n-layer variation, are subject to poor photovoltaic efficiency, particularly in the fill factor (FF), compared to their three-dimensional counterparts. To enhance the performance of DJ PSCs, the process of growing crystals and hence the corresponding morphology of DJ perovskites are of prime importance. Herein, we report the fast nonisothermal (NIT) crystallization protocol that is previously unrecognized for 2D perovskites to significantly improve the morphology, orientation, and charge transport of the DJ perovskite films. Comprehensive mechanistic studies reveal that the NIT effect leads to the secondary crystallization stage, forming network-like channels that play a vital role in the FF's leap-forward improvement and hence the DJ PSC's performance. As a whole, the NIT crystallized PSCs demonstrate a high power conversion efficiency and an FF of up to 19.87 and 86.16%, respectively. This research thus provides new perspectives to achieve highly efficient DJ PSCs.

Tin perovskite solar cells (PSCs) have been attracting attention in photovoltaic application, while the performance of Sn PSCs, especially for hole-transporting materials (HTMs)-free configuration, is relatively poor because of short mean-free-path for photogenerated charge carriers. We report a p–n junction with spatially appropriate architecture and energetic alignment in perovskite light-absorbing layer, resulting in an excellent performance of HTM-free Sn PSCs with a power conversion efficiency (PCE) of 5.17%, the highest value reported in HTM-free Sn PSCs. The p–n junction configuration plays a key role in achieving high efficiency and realizing excellent stability for more than 200 h operation.