David Avellaneda Avellaneda

Nanoparticles in their pure colloidal form synthesized by laser-assisted processes such as laser ablation/fragmentation/irradiation/melting in liquids have attained much interest from the scientific community because of their specialties like facile synthesis, ultra-high purity, biocompatibility, colloidal stability in addition to other benefits like tunable size and morphology, crystalline phases, new compounds and alloys, and defect engineering. These nanocolloids are useful for fabricating different devices mainly with applications in optoelectronics, catalysis, sensors, photodetectors, surface-enhanced Raman spectroscopy (SERS) substrates, and solar cells. In this review article, we describe different methods of nanocolloidal synthesis using laser-assisted processes and corresponding thin film fabrication methods, particularly those utilized for device fabrication and characterization. The four sections start with an introduction to the common laser-assisted synthesis for nanocolloids and different methods of thin film fabrication using these nanocolloids followed by devices fabricated and characterized for applications including photovoltaics, photodetectors, catalysis, photocatalysis, electrochemical/photoelectrochemical sensors, hydrogen/oxygen evolution, SERS sensors and other types of devices reported so far. The last section explains the challenges and further scope of these devices from laser-generated nanocolloids.

In this work, we report the fabrication of CuI@g-C₃N₄/MoS₂ thin films by the thermal evaporation of Cu films and their conversion into hybrid films by a simple wet chemical method. Compared to pure CuI, CuI@g-C₃N₄/MoS₂ shows enhanced absorption near the UV region, which improves its DC photoconductivity. The conductivity of the films is enhanced by the addition of g-C₃N₄/MoS₂, which is distributed on the surface of the CuI film. The band gap of the films red-shifts upon adding g-C₃N₄/MoS₂. We evaluate this material’s potential application as a photodetector and in photocatalysis by evaluating its photoelectrochemical properties using impedance spectroscopy measurements, cyclic voltammetry, and DC photoresponse measurements. We find that upon the addition of g-C₃N₄/MoS₂, the conductivity of the films is increased, as evidenced by the time-dependent photo amperometry measurements. Also, a higher DC photoresponse is observed upon increasing the concentration of MoS₂. This work marks the first time a hybrid CuI@g-C₃N₄/MoS₂ film and its photoelectrochemical characteristics have ever been reported.

Photodetectors are indispensable components of many modern light sensing and imaging devices, converting photon energy into processable electrical signal through absorption, carrier generation and extraction using semiconducting thin films with appropriate optoelectronic properties. Recently, metal halide perovskites have demonstrated groundbreaking photodetector performance due to their exceptional properties originating from their perovskite structure. However, toxicity and stability remain challenges for their large-scale applications. Inspired by the perovskite structure, intense investigation in search of highly stable, non-toxic and earth abundant materials with superior optoelectronic features has led to the discovery of chalcogenide perovskites (CPs). These are unconventional semiconductors with the formula ABX₃, where A and B are cations and X is a chalcogen, which covers the compounds with the corner sharing perovskite structures of type II-IV- VI₃ compounds (II = Ba, Sr, Ca, Eu; IV = Zr, Hf; VI = S, Se) and III₁-III₂-VI₃ compounds (III₁ and III₂ = Lanthanides, Y, Sc; VI = S, Se). The increased coordination and ionicity in these compounds contribute to their excellent charge transport properties and exceptionally high optical absorption coefficient (> 10⁵ cm⁻¹). The present review encompasses theoretical analysis that provides electronic band structures and the orbital contributions that support the excellent optoelectronic properties. Furthermore, the challenging thin film deposition, characterizations, and their application in photodetection focusing on BaZrS₃-which is the most studied one, are ascribed. Additionally, we suggest prospects that can bring out the true potential of these materials in photodetection and photovoltaics.

En entrevista para la UANL, el Dr. David Avellaneda Avellaneda describe la síntesis de semiconductores para el desarrollo de dispositivos fotovoltaicos y celdas solares como su principal línea de investigación dentro del Programa Doctoral en Ingeniería de