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The formation of nanoscale junctions among nanoparticles in self-assembled nanostructures is crucial for improving both interfacial conductivity and structural integrity. However, the inherent reliance on weak van der Waals forces to hold nanoparticles together poses challenges in developing commercially viable devices due to their inefficient carrier transport characteristics. This study presents the successful integration of carbon nanotubes (CNTs) into highly porous nanomicrocluster arrays of ZnO, resulting in the formation of cohesive and crack-free highly porous ZnO/CNT heterojunction films. This integration marks a significant improvement in UV photodetection performance, demonstrating a record-high photocurrent to dark current ratio of 3.3 × 10 6 and an exceptional responsivity of 18.5 A/W at a low bias of 0.5 V and under an ultra low light density of 25 μW/cm 2 . These findings underscore the efficacy of this high-performance structure as a versatile and scalable platform technology for the rapid, cost-effective fabrication of hybrid photodetectors in wearable and portable devices.

The charge-transfer chemical mechanism is responsible for altering the molecular spectral pattern and providing valuable insights into the properties of adsorbates. The impact of charge transfer becomes more pronounced in SERS spectra when CT states can gain intensity through vibronic coupling with high-intensity excitations. Experimental SERS spectra of diamino molecules, such as 4,4'-diaminostilbene (DAS) and 4,4'-diaminotolane (DAT), featuring bright CT transitions, have been compared to dipyridyl compounds, such as 1,2-bis(4-pyridyl) ethylene (BPE) and 1,2-di(4-pyridyl) acetylene (DPA), characterized by nearly dark CT excitations. This comparison aims to elucidate the effect of CT transitions on the presence of overtones and combination bands. We explain this distinction using Albrecht's formalism for resonance Raman spectroscopy within the framework of path integral time-dependent density functional theory considering the Herzberg-Teller corrections. It is worth noting that the energy gap between the highest occupied metallic orbital and the lowest unoccupied molecular orbital in diamino derivatives is noticeably smaller than in compounds featuring two pyridyl rings. The high-intensity SERS-CT spectra for diamino derivatives, primarily driven by the Albrecht A term, were acquired and used to elucidate the experimental observation of high-order modes with a significant Huang-Rhys factor. Conversely, the absolute intensity of SERS-CT for dipyridyl compounds is at least 10 6 times smaller than that for diamines, and the C term makes a significant contribution, explaining the silent overtones.

In this work, we demonstrate the performance of a silicon-compatible, high-performance, and self-powered photodetector. A wide detection range from visible (405 nm) to near-infrared (1550 nm) light was enabled by the vertical p-n heterojunction between the p-type antimony telluride (Sb 2 Te 3 ) thin film and the n-type silicon (Si) substrates. A Sb 2 Te 3 film with a good crystal quality, low density of extended defects, proper stoichiometry, p-type nature, and excellent uniformity across a 4 in. wafer was achieved by atomic layer deposition at 80 °C using (Et 3 Si) 2 Te and SbCl 3 as precursors. The processed photodetectors have a low dark current (∼20 pA), a high responsivity of (∼4.3 A/W at 405 nm and ∼150 mA/W at 1550 nm), a peak detectivity of ∼1.65 × 10 14 Jones, and a quick rise time of ∼98 μs under zero bias voltage. Density functional theory calculations reveal a narrow, near-direct, type-II band gap at the heterointerface that supports a strong built-in electric field leading to efficient separation of the photogenerated carriers. The devices have long-term air stability and efficient switching behavior even at elevated temperatures. These high-performance and self-powered p-Sb 2 Te 3 /n-Si heterojunction photodetectors have immense potential to become reliable technological building blocks for a plethora of innovative applications in next-generation optoelectronics, silicon-photonics, chip-level sensing, and detection.

Transparent conductive oxides (TCOs) are highly desirable for numerous applications ranging from photovoltaics to light-emitting diodes and photoelectrochemical devices. Despite progress, it remains challenging to fabricate porous TCOs (pTCOs) that may provide, for instance, a hierarchical nanostructured morphology for the separation of photoexcited hole/electron couples. Here, we present a facile process for the fabrication of porous architectures of aluminum-doped zinc oxide (AZO), a low-cost and earth-abundant transparent conductive oxide. Three-dimensional nanostructured films of AZO with tunable porosities from 10 to 98% were rapidly self-assembled from flame-made nanoparticle aerosols. Successful Al doping was confirmed by X-ray photoemission spectroscopy, high-resolution transmission electron microscopy, elemental mapping, X-ray diffraction, and Fourier transform infrared spectroscopy. An optimal Al-doping level of 1% was found to induce the highest material conductivity, while a higher amount led to partial segregation and formation of aluminum oxide domains. A controllable semiconducting to conducting behavior with a resistivity change of more than 4 orders of magnitudes from about 3 × 10 2 to 9.4 × 10 6 Ω cm was observed by increasing the AZO film porosity from 10 to 98%. While the denser AZO morphologies may find immediate application as transparent electrodes, we demonstrate that the ultraporous semiconducting layers have potential as a light-driven gas sensor, showing a high response of 1.92-1 ppm of ethanol at room temperature. We believe that these tunable porous transparent conductive oxides and their scalable fabrication method may provide a highly performing material for future optoelectronic devices.

Bone osteogenesis is a complex phenomenon dependent on numerous microenvironmental cues, with their synchrony regulating cellular functions, such as mechanical signaling, survival, proliferation, and differentiation, as well as controlled regional specification of skeletal progenitor cell fate. Therefore, obtaining a mechanistic understanding of cellular response to a microenvironment is now coming into intense focus, which will facilitate the design of programmable biomaterials for regenerative medicine. State-of-the-art nanomaterial synthesis and self-assembly processes yield complex structures that mimic surface properties, composition, and partially the morphology of the extracellular matrix. However, determining key structural properties that control cell attachment has been challenging and contradictory results are reported regarding the mechanisms and roll of nanostructured materials. Here, we significantly improve osteogenesis on bioinert substrates, demonstrating an exemplary organic-inorganic interface for superior prosthesis biointegration. We identify critical microscale hierarchical features that drastically enhance the cellular response to the same nanoscale architecture. It was observed that hierarchical morphologies, with a porosity above 80%, promote early-stage osteoinduction, as indicated by extensive coating ingrowth and nanofilopodia formation. We determined that cellular integration was mediated by two-way recognition of specific nano- and microtopographical cues between the host tissue and cellular microenvironment. This has allowed us to detail a set of determinant features for the nanofabrication of advanced prosthesis coatings that may ultimately improve implant longevity.

Accurate detection of UV light by wearable low-power devices has many important applications including environmental monitoring, space to space communication, and defense. Here, we report the structural engineering of ultraporous ZnO nanoparticle networks for fabrication of very low-voltage high-performance UV photodetectors. A record high photo- to dark-current ratio of 3.3 × 10 5 and detectivity of 3.2 × 10 12 Jones at an ultralow operation bias of 2 mV and low UV-light intensity of 86 μW·cm -2 are achieved by controlling the interplay between grain boundaries and surface depletion depth of ZnO nanoscale semiconductors. An optimal window of structural properties is determined by varying the particle size of ultraporous nanoparticle networks from 10 to 42 nm. We find that small electron-depleted nanoparticles (≤40 nm) are necessary to minimize the dark-current; however, the rise in photocurrent is tampered with decreasing particle size due to the increasing density of grain boundaries. These findings reveal that nanoparticles with a size close to twice their Debye length are required for high photo- to dark-current ratio and detectivity, while further decreasing their size decreases the photodetector performance.

Engineering surface textures that are highly transparent and repel water, oil, and other low surface energy fluids can transform our interaction with wet environments. Despite extensive progress, current top-down methods are based on directional line-of-sight fabrication mechanisms that are limited by scale and cannot be applied to highly uneven, curved, and enclosed surfaces, while bottom-up techniques often suffer from poor optical transparency. Here, we present an approach that enables the rapid, omnidirectional synthesis of flexible and up to 99.97% transparent superhydrophobic and -oleophobic textures on many variable surface types. These features are obtained by the spontaneous formation of a multi re-entrant morphology during the controlled self-assembly of nanoparticle aerosols. We also develop a mathematical model to explain and control the self-assembly dynamics, providing important insights for the rational engineering of functional materials. We envision that our findings represent a significant advance in imparting superoleophobicity and superamphiphobicity to a so-far inapplicable family of materials and geometries for multifunctional applications.