Cuihong Li

The thermochromic and mechanochromic fluorescence of diphenyldibenzofulvenes is investigated. Emission is boosted and blue-shifted upon crystallization. Yellow emissive crystals of the material transform to green fluorescent crystals upon heating before melting. Reversible switching of the emission color and efficiency are achieved by repeated amorphization and crystallization of dye molecules by a pure thermal process or grinding–heating cycles.

An alternating copolymer, poly(2-(5-(5,6-bis(octyloxy)-4-(thiophen-2-yl)benzo[c][1,2,5]thiadiazol-7-yl)thiophen-2-yl)-9-octyl-9H-carbazole) (HXS-1), was designed, synthesized, and used as the donor material for high efficiency polymer solar cells. The close packing of the polymer chains in the solid state was confirmed by XRD. A J(sc) of 9.6 mA/cm(2), a V(oc) of 0.81 V, an FF of 0.69, and a PCE of 5.4% were achieved with HXS-1 and [6,6]-phenyl C(71)-butyric acid methyl ester (PC(71)BM) as a bulk heterojunction active layer spin-coated from a solvent mixture of 1,2-dichlorobenzene and 1,8-diodooctane (97.5:2.5) under air mass 1.5 global (AM 1.5 G) irradiation of 100 mW/cm(2).

Non-fullerene fused-ring electron acceptors boost the power conversion efficiency of organic solar cells, but they suffer from high synthetic cost and low yield. Here, we show a series of low-cost noncovalently fused-ring electron acceptors, which consist of a ladder-like core locked by noncovalent sulfur-oxygen interactions and flanked by two dicyanoindanone electron-withdrawing groups. Compared with that of similar but unfused acceptor, the presence of ladder-like structure markedly broadens the absorption to the near-infrared region. In addition, the use of intramolecular noncovalent interactions avoids the tedious synthesis of covalently fused-ring structures and markedly lowers the synthetic cost. The optimized solar cells displayed an outstanding efficiency of 13.24%. More importantly, solar cells based on these acceptors demonstrate very low non-radiative energy losses. This research demonstrates that low-cost noncovalently fused-ring electron acceptors are promising to achieve high-efficiency organic solar cells.

Stepwise locking of phenyl rings of tetraphenylethene increases the emission efficiency of luminogen solutions gradually, thus verifying the restriction of intramolecular rotation (RIR) mechanism of the aggregation induced emission phenomenon. The emission of the luminogen with one "O" bridge could be tuned reversibly in solid state through repeated heating and grinding.

On–off-switchable, persistent, room-temperature phosphorescence (373 ms) is realized in organic solids based on bis(4-(9H-carbazol-9-yl)phenyl)methanone. The reversible on–off RTP switching can be controlled by repeatedly chloroform fuming and heating (or grinding). Multi­ple-color fluorescence is also feasible, and they reversibly convert to each other under the stimuli of heating, shearing, and fuming with varied solvents. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.