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Artificial retinas require materials and devices that can interface with the nervous system. Here, aluminum antimonide colloidal nanocrystals are used as the interfacing layer with a biological medium, showing a fast photoresponse of 55 µs and a suggested operational lifetime of 36 months.

Light-emitting diodes (LEDs) based on CsPbBr3 nanocrystals (NCs) show excellent performance in terms of external quantum efficiency (EQE) and brightness. Removal of impurities after NC synthesis is a necessary and critical step to achieve such high performance. In fact, the optical and electronics properties of CsPbBr3 NCs are greatly affected by how the NCs are purified from the synthetic by-products, unreacted reagents, and organic ligand excess. Perovskite NC purification protocols must consider the ionic nature of the inorganic core, the labile nature of the ligand to surface bond, and the dynamic equilibrium between the surface-interacting and free form organic ligands to prevent NC damaging with subsequent loss of photoluminescence. Nowadays, the most employed purification protocol involves NC precipitation based on a diminished non-polar environment achieved by adding a low-dielectric constant miscible solvent to the NC solution (i.e., ethyl acetate to toluene), followed by redispersion of the precipitate in a storage solvent. Here, we explored the possibility to precipitate impurities left in the NC solution exploiting variations in solubility at decreasing temperature: by taking NC solutions at −20 °C overnight and by collecting the respective supernatant we obtain CsPbBr3 NC solutions which leads to LEDs with improved EQE. The freezing process at −20 °C gives rise to NC solutions that retain the pristine optical and electronic properties while the LED performances display a 3 times increase in terms of EQE (EQEmax = 8.9%) with respect to NCs treated with anti-solvent only. Finally, we show that our purification protocol can be applied to CsPbBr3 NCs obtained via different synthetic methods, thus demonstrating the versatility of our facile purification protocol.

Light-activated biointerfaces provide a non-genetic route for effective control of neural activity. InP quantum dots (QDs) have a high potential for such biomedical applications due to their uniquely tunable electronic properties, photostability, toxic-heavy-metal-free content, heterostructuring, and solution-processing ability. However, the effect of QD nanostructure and biointerface architecture on the photoelectrical cellular interfacing remained unexplored. Here, we unravel the control of the photoelectrical response of InP QD-based biointerfaces via nanoengineering from QD to device-level. At QD level, thin ZnS shell growth (∼0.65 nm) enhances the current level of biointerfaces over an order of magnitude with respect to only InP core QDs. At device-level, band alignment engineering allows for the bidirectional photoelectrochemical current generation, which enables light-induced temporally precise and rapidly reversible action potential generation and hyperpolarization on primary hippocampal neurons. Our findings show that nanoengineering QD-based biointerfaces hold great promise for next-generation neurostimulation devices.

Summary: Colloidal quantum dots (QDs) are promising building blocks for luminescent solar concentrators (LSCs). For their widespread use, they need to simultaneously satisfy non-toxic material content, low reabsorption, high photoluminescence quantum yield, and large-scale production. Here, copper doping of zinc carboxylate-passivated InP core and nano-engineering of ZnSe shell facilitated high in-device quantum efficiency of QDs over 80%, having well-matched spectral emission profile with the photo-response of silicon solar cells. The optimized QD-LSCs showed an optical quantum efficiency of 37% and an internal concentration factor of 4.7 for a 10 × 10-cm2 device area under solar illumination, which is comparable with the state-of-the-art LSCs based on cadmium-containing QDs and lead-containing perovskites. Synthesis of the copper-doped InP/ZnSe QDs in gram-scale and large-area deposition (3,000 cm2) onto commercial window glasses via doctor-blade technique showed their scalability for mass production. These results position InP-based QDs as a promising alternative for efficient solar energy harvesting.

Herein, we demonstrate that the structural and optical control of InP-based quantum dots (QDs) can lead to high-performance light-emitting diodes (LEDs). Zinc sulphide (ZnS) shells passivate the InP QD core and increase the quantum yield in green-emitting QDs by 13-fold and red-emitting QDs by 8-fold. The optimised QDs are integrated in the liquid state to eliminate aggregation-induced emission quenching and we fabricated white LEDs with a warm, neutral and cool-white appearance by the down-conversion mechanism. The QD-functionalized white LEDs achieve luminous efficiency (LE) up to 14.7 lm W−1 and colour-rendering index up to 80. The structural and optical control of InP/ZnS core/shell QDs enable 23-fold enhancement in LE of white LEDs compared to ones containing only QDs of InP core. [ABSTRACT FROM AUTHOR]