We have designed and synthesised two new carbazole based self-assembled molecules as hole-selective layers (HSLs) in p–i–n perovskite solar cells achieving high efficiency and high stability.

Electrochromism/electrofluorochromism is the reversible tuning of the absorption/photoluminescence by redox processes. Dual functional electrochromic/electrofluorochromic materials can be exploited in, for example, smart windows, encryption/anticounterfeiting technologies, displays, and biomedical sensors. While electrofluorochromic materials showing tunable fluorescence intensity are relatively widespread, those with tunable color emission are not. Moreover, electrofluorochromic materials with tunable emission in the near‐infrared (NIR) range are seldom encountered. Here, this work shows a new molecular approach to afford both the above functionalities, in addition to red–NIR electrochromism, by combining the properties of highly stable arylamine radical cation mixed valence species, with those of donor–acceptor systems exhibiting the photoinduced twisted intramolecular charge transfer mechanism.

Metal halide perovskite nanocrystals have demonstrated their potential as light sources when forming part of efficient light emitting diodes (LEDs). However, operational stability and efficiency are compromised primarily because of...