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Transparent electrodes based on emerging nanomaterials like silver nanowire (AgNW) networks have been extensively investigated in the past few years. Thanks to their superior flexibility and versatility in terms of fabrication and device integration, they present an excellent alternative to indium tin oxide. However, the lack of thermal, electrical, and chemical stability requires the encapsulation of the AgNW. This has been performed using thin metal oxide films, graphene, or organic protective coatings. Despite the very promising properties of such nanocomposite approaches and the performance enhancement, more investigation is needed to minimize the loss of optical transmittance upon coating and achieve superior electrical, thermal, and mechanical stability. In the present work, the encapsulation of AgNW networks with aluminum nitride (AlN) coatings is reported for the first time, and it is compared to AgNW/Al2O3 nanocomposites. Thanks to the low thicknesses (<20 nm) and the wide band gap of AlN, the optical transparency is not impacted. Furthermore, the nanocomposite networks demonstrate no failure under electrical and thermal stress conditions (up to 21 V and 400 °C respectively), in contrast to the AgNW/Al2O3 nanocomposites, which fail after 15 V and 350 °C. In addition, microscratch tests reveal the remarkable mechanical robustness of the nanocomposites, and the electrical stability is further confirmed under accelerated environmental tests, coupled with ex situ characterization by SEM and XPS. The results reported in the present work show that AgNW/AlN electrodes are outstanding candidates for high-performance transparent electrodes. [ABSTRACT FROM AUTHOR]

In situ biological observations require stable, accurate, and local temperature control of specimen. Several heating elements are coupled with microfluidic systems, but few of them are transparent to visible light and therefore compatible with microscopic observation. Traditional transparent electrodes, such as indium tin oxide, still suffer from high fabrication cost and brittleness, which is not fully compatible to emerging microfluidic devices. Here, a lightweight, low‐cost, flexible transparent heater based on percolating silver nanowire networks, protected with a transparent zinc oxide film, for the in situ monitoring of biological experiments is proposed. Using the fluorescence of dyes bound to double‐stranded DNA to monitor its temperature in situ, it is demonstrated that such nanocomposites allow rapid and reproducible heating under low applied voltage. Furthermore, selective heating is achieved in different zones of the same microchannel or for adjacent microchannels of the chip heating at different temperatures, with a single transparent heater and bias. [ABSTRACT FROM AUTHOR]

Cuprous oxide (Cu2O) is a promising p-type semiconductor material for many applications. So far, the lowest resistivity values are obtained for films deposited by physical methods and/or at high temperatures (~1000 °C), limiting their mass integration. Here, Cu2O thin films with ultra-low resistivity values of 0.4 Ω.cm were deposited at only 260 °C by atmospheric pressure spatial atomic layer deposition, a scalable chemical approach. The carrier concentration (7.1014−2.1018 cm−3), mobility (1–86 cm2/V.s), and optical bandgap (2.2–2.48 eV) are easily tuned by adjusting the fraction of oxygen used during deposition. The properties of the films are correlated to the defect landscape, as revealed by a combination of techniques (positron annihilation spectroscopy (PAS), Raman spectroscopy and photoluminescence). Our results reveal the existence of large complex defects and the decrease of the overall defect concentration in the films with increasing oxygen fraction used during deposition. Cu2O offers a lot of potential for several optoelectronic applications. Here, the authors present a low temperature, fast and scalable approach to deposit Cu2O films with low resistivity, which is correlated to the defect landscape in the material. [ABSTRACT FROM AUTHOR]

Due to its unique optical, electrical, and chemical properties, tin dioxide (SnO2) thin films attract enormous attention as a potential material for gas sensors, catalysis, low-emissivity coatings for smart windows, transparent electrodes for low-cost solar cells, etc. However, the low-cost and high-throughput fabrication of SnO2 thin films without producing corrosive or toxic by-products remains challenging. One appealing deposition technique, particularly well-adapted to films presenting nanometric thickness is atomic layer deposition (ALD). In this work, several metalorganic tin-based complexes, namely, tin(IV) tert-butoxide, bis[bis(trimethylsilyl)amino] tin(II), dibutyltin diacetate, tin(II) acetylacetonate, tetrakis(dimethylamino) tin(IV), and dibutyltin bis(acetylacetonate), were explored thanks to DFT calculations. Our theoretical calculations suggest that the three last precursors are very appealing for ALD of SnO2 thin films. The potential use of these precursors for atmospheric-pressure spatial atomic layer deposition (AP-SALD) is also discussed. For the first time, we experimentally demonstrate the AP-SALD growth of SnO2 thin films using tin(II) acetylacetonate (Sn(acac)2) and water. We observe that Sn(acac)2 exhibits efficient ALD activity with a relatively large ALD temperature window (140–200 °C), resulting in a growth rate of 0.85 ± 0.03 Å per cyc. XPS analyses show a single Sn 3d5/2 characteristic peak for Sn4+ at 486.8 ± 0.3 eV, indicating that a pure SnO2 phase is obtained within the ALD temperature window. The as-deposited SnO2 thin films are in all cases amorphous, and film conductivity increases with the deposition temperature. Hall effect measurements confirm the n-type nature of SnO2 with a free electron density of about 8 × 1019 cm−3, electron mobility up to 11.2 cm2 V−1 s−1, and resistivity of 7 × 10−3 Ω cm for samples deposited at 270 °C. [ABSTRACT FROM AUTHOR]

Recent research focuses on finding alternative materials and fabrication techniques to replace traditional (p) and (n) doped hydrogenated amorphous silicon (a-Si:H) to reduce cost and boost the efficiency of silicon heterojunction (SHJ) solar cells. In this work, low-cost p-type Cu2O thin films have been investigated and integrated as a hole-transporting layer (HTL) in SHJ solar cells, using atmospheric-pressure spatial atomic layer deposition (AP-SALD), an open-air, scalable ALD approach. Phase pure Cu2O thin films have been deposited at temperatures below the degradation limit of the SHJ, thus maintaining the passivation effect of the a-Si:H layer. The effect of deposition temperatures and HTL thicknesses on the performance of the devices has been evaluated. The fabricated Cu2O HTL-based SHJ cells, having an area of 9 cm2, reach a power conversion efficiency (PCE) of 13.7%, which is the highest reported efficiency for silicon-based solar cells incorporating a Cu2O HTL. [ABSTRACT FROM AUTHOR]

Due to its unique optical, electrical, and chemical properties, tin dioxide (SnO 2 ) thin films attract enormous attention as a potential material for gas sensors, catalysis, low-emissivity coatings for smart windows, transparent electrodes for low-cost solar cells, etc . However, the low-cost and high-throughput fabrication of SnO 2 thin films without producing corrosive or toxic by-products remains challenging. One appealing deposition technique, particularly well-adapted to films presenting nanometric thickness is atomic layer deposition (ALD). In this work, several metalorganic tin-based complexes, namely, tin(IV) tert -butoxide, bis[bis(trimethylsilyl)amino] tin(II), dibutyltin diacetate, tin(II) acetylacetonate, tetrakis(dimethylamino) tin(IV), and dibutyltin bis(acetylacetonate), were explored thanks to DFT calculations. Our theoretical calculations suggest that the three last precursors are very appealing for ALD of SnO 2 thin films. The potential use of these precursors for atmospheric-pressure spatial atomic layer deposition (AP-SALD) is also discussed. For the first time, we experimentally demonstrate the AP-SALD growth of SnO 2 thin films using tin(II) acetylacetonate (Sn(acac) 2 ) and water. We observe that Sn(acac) 2 exhibits efficient ALD activity with a relatively large ALD temperature window (140-200 °C), resulting in a growth rate of 0.85 ± 0.03 Å per cyc. XPS analyses show a single Sn 3d 5/2 characteristic peak for Sn 4+ at 486.8 ± 0.3 eV, indicating that a pure SnO 2 phase is obtained within the ALD temperature window. The as-deposited SnO 2 thin films are in all cases amorphous, and film conductivity increases with the deposition temperature. Hall effect measurements confirm the n-type nature of SnO 2 with a free electron density of about 8 × 10 19 cm -3 , electron mobility up to 11.2 cm 2 V -1 s -1 , and resistivity of 7 × 10 -3 Ω cm for samples deposited at 270 °C.