Blue-luminescence materials are needed in urgency. Recently, zero-dimensional (0D) organic metal halides have attractive much attention due to unique structure and excellent optical properties. However, realizing blue emission with near-UV-visible light excitation in 0D organic metal halides is still a great challenge due to their generally large Stokes shifts. Here, we reported a new (0D) organic metal halides (TPA)₂PbBr₄ single crystal (TPA⁺ = tetrapropylammonium cation), in which the isolated [PbBr₄]²⁻ tetrahedral clusters are surrounded by organic ligand of TPA⁺, forming a 0D framework. Upon photoexcitation, (TPA)₂PbBr₄ exhibits a blue emission peaking at 437 nm with a full width at half-maximum (FWHM) of 50 nm and a relatively small Stokes shift of 53 nm. Combined with density functional theory (DFT) calculations and spectral analysis, it is found that the observed blue emission in (TPA)₂PbBr₄ comes from the combination of free excitons (FEs) and self-trapped exciton (STE), and a small Stokes shift of this compound are caused by the small structure distortion of [PbBr₄]²⁻ cluster in the excited state confined by TPA molecules, in which the multi-phonon effect take action. Our results not only clarify the important role of excited state structure distortion in regulating the STEs formation and emission, but also focus on 0D metal halides with bright blue emission under the near-UV-visible light excitation.

In this work, we performed a systematic comparison of different duration of solvent vapor annealing (SVA) treatment upon state-of-the-art PM6:SY1 blend film, which is to say for the first time, the insufficient, appropriate, and over-treatment’s effect on the active layer is investigated. The power conversion efficiency (PCE) of corresponding organic solar cell (OSC) devices is up to 17.57% for the optimized system, surpassing the two counterparts. The properly tuned phase separation and formed interpenetrating network plays an important role in achieving high efficiency, which is also well-discussed by the morphological characterizations and understanding of device physics. Specifically, these improvements result in enhanced charge generation, transport, and collection. This work is of importance due to correlating post-treatment delicacy, thin-film morphology, and device performance in a decent way.

Multicomponent organic solar cells (OSCs), such as the ternary and quaternary OSCs, not only inherit the simplicity of binary OSCs but further promote light harvesting and power conversion efficiency (PCE). Here, we propose a new type of multicomponent solar cells with non-fullerene acceptor isomers. Specifically, we fabricate OSCs with the polymer donor J71 and a mixture of isomers, ITCF, as the acceptors. In comparison, the ternary OSC devices with J71 and two structurally similar (not isomeric) NFAs (IT-DM and IT-4F) are made as control. The morphology experiments reveal that the isomers-containing blend film demonstrates increased crystallinity, more ideal domain size, and a more favorable packing orientation compared with the IT-DM/IT-4F ternary blend. The favorable orientation is correlated with the balanced charge transport, increased exciton dissociation and decreased bimolecular recombination in the ITCF-isomer-based blend film, which contributes to the high fill factor (FF), and thus the high PCE. Additionally, to evaluate the generality of this method, we examine other acceptor isomers including IT-M, IXIC-2Cl and SY1, which show same trend as the ITCF isomers. These results demonstrate that using isomeric blends as the acceptor can be a promising approach to promote the performance of multicomponent non-fullerene OSCs.

Multicolor emission and dynamic color tuning with large spectral range are challenging to realize but critically important in many areas of technology and daily life, such as general lighting, display, multicolor detection and multi-band communication. Herein, we report an excitation-power-dependent color-tuning emission from an individual Sn-doped CdS nanowire with a large spectral range and continuous color tuning. Its photoluminescence (PL) spectrum shows a broad trap-state emission band out of Sn dopants, which is superposed by whispering-gallery (WG) microcavity due to the nanostructure size and its structure, besides the CdS band-edge emission. By simply changing the excitation power from 0.25 to 1.36 mW, we demonstrate that the typical Sn-doped CdS nanowire with the weight ratio of 10:1 of CdS and SnO₂, the emission color can change from red to orange to yellow to green. In view of the stable properties and large spectral range, the Sn-doped CdS nanowires are very promising potential candidates in nanoscale optoelectronic devices.