Researchers achieved ultrahigh efficiency of solution-processed simplified small-molecule OLEDs that use novel universal host materials.

Visible-blind ultraviolet (UV) photodetectors have received a great deal of attention for realizing Internet of Things technologies as well as for monitoring the level of UV exposure to humans. Realizing next-generation flexible and visible-blind UV photodetectors requires development of new functional material systems with easy fabrication, selectively strong UV light absorption, environmental friendliness, and high stability regardless of ambient conditions. Herein, flexible visible-blind UV photodetectors are successfully fabricated on the basis of two-dimensional ZnAl-layered double hydroxide (LDH) nanosheets with scroll structures grown on flexible substrates. The ZnAl-LDH nanosheet scrolls exhibit highly resistive semiconducting properties with a band gap of 3.2 eV and work function of 3.64 eV. The photodetector based on the ZnAl-LDH shows photoresponse in the UV spectral range below 420 nm, indicating visible-blind spectral response. In addition, the UV photodetector shows a maximum responsivity of 17 mA/W under illumination with 365 nm light. Moreover, the flexible photodetector shows reproducible photoresponse even after 1000 bending cycles, which indicates the acceptable stability of the ZnAl-LDH nanosheet scrolls.

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A series of small molecules that contained identical π-spacers (ethyne), a central diketopyrrolopyrrole (DPP) unit, and different aromatic electron-donating end-groups were synthesized and used in organic solar cells (OSCs) to study the effect of electron-donating groups on the device performance. The three compounds, DPP-A-Ph, DPP-A-Na, and DPP-A-An, possessed intense absorption bands that covered a wide range, from 350 to 750 nm, and relatively low HOMO energy levels, from -5.50 to -5.55 eV. DPP-A-An, which contained anthracene end-groups, demonstrated a stronger absorbance and a higher hole mobility than DPP-A-Ph, which contained phenyl groups, and DPP-A-Na, which contained naphthalene units. The power-conversion efficiencies (PCEs) of OSCs based on organic:PC71BM blends (1:1, w/w) with a processed DIO additive were 3.93% for DPP-A-An, 3.02% for DPP-Na, and 2.26% for DPP-A-Ph. These findings suggest that a DPP core that is functionalized with electron-donating capping groups constitutes a promising new class of solution-processable small molecules for OSC applications.

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Layered double hydroxide (LDH)‐based materials, which are 2D materials, have received considerable attention because of their structural diversity and electronic functionality. In article number 2001990, Jingon Jang, Gunuk Wang, and co‐workers have reported a new type of transparent and unipolar nonvolatile memory that is developed based on a two‐terminal Pt/ZnAl‐LDH/FTO junction, where its switching filament is formed through the self‐organized vertical stacked ZnAl‐LDH structure.

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