Mechanofluorochromic molecular materials display a change in fluorescence color through mechanical stress. Complex structure–property relationships in both the crystalline and amorphous phases of these materials govern both the presence and strength of this behavior, which is usually deemed the result of a mechanically induced phase transition. However, the precise nature of the emitting species in each phase is often a matter of speculation, resulting from experimental data that are difficult to interpret, and a lack of an acceptable theoretical model capable of capturing complex environmental effects. With a combined strategy using sophisticated experimental techniques and a new theoretical approach, here the varied mechanofluorochromic behavior of a series of difluoroboron diketonates is shown to be driven by the formation of low‐energy exciton traps in the amorphous phase, with a limited number of traps giving rise to the full chang...
Designing organic molecules efficient for charge extraction and transport when integrated in optoelectronic
devices remains a great challenge for many advanced applications. In perovskite solar cells (PSCs), the hole
extraction/transport and the device stability are strongly dependent on the molecular structure of the hole
transporting material (HTM). Herein we have engineered a dendritic core carbazole
based HTM (named B186),
which combines the advantages of both small molecules and polymeric materials. The material can be easily
prepared in a short synthetic procedure from largely available commercial products. We have investigated indepth
the relationship between the chemical structure of the HTM and both the photovoltaic efficiency and the
device stability. It has been shown that the dendritic core is a promising approach leading to both enhanced
device performance and stability. The new HTM has been proved to act as a good...