KCN Chemical Etching of van der Waals SbSe Thin Films Synthesized at Low Temperature Leads to Inverted Surface Polarity and Improved Solar Cell Efficiency.

Recent developments in SbSe van der Waals material as an absorber candidate for thin film photovoltaic applications have demonstrated the importance of surface management for improving the conversion efficiency of this technology. SbSe thin films' versatility in delivering good efficiencies in both superstrate and substrate configurations, coupled with a compatibility with various low-temperature deposition techniques (below 500 °C and often below 350 °C), makes them highly attractive for advanced photovoltaic applications. This study presents a comparative analysis of the most effective chemical etchings developed for related thin film chalcogenide technologies to identify and understand the most appropriate surface chemical treatments for SbSe in substrate configuration, synthesized using a sequential process at very low temperatures (320 °C).

SbSeI and SbSeBr micro-columnar solar cells by a novel high pressure-based synthesis process.

Van der Waals chalcogenides and chalcohalides have the potential to become the next thin film PV breakthrough, owing to the earth-abundancy and non-toxicity of their components, and their stability, high absorption coefficient and quasi-1D structure, which leads to enhanced electrical anisotropic properties when the material is oriented in a specific crystalline direction. However, quasi-1D semiconductors beyond Sb(S,Se), such as SbSeX chalcohalides, have been scarcely investigated for energy generation applications, and rarely synthesised by physical vapor deposition methodologies, despite holding the promise of widening the bandgap range (opening the door to tandem or semi-transparent devices), and showing enticing new properties such as ferroelectric behaviour and defect-tolerant nature. In this work, SbSeI and SbSeBr micro-columnar solar cells have been obtained for the first time by an innovative methodology based on the selective halogenation of SbSe thin films at pressure above 1 atm.

Two-Dimensional Synergistic Interfacial Orientation on Tin Oxide-Reinforced Cobalt Carbonate Hydroxide Heterostructures for High-Performance Energy Storage.

A hierarchical cobalt carbonate hydroxide (CCH) nanostructure with outstanding electrochemical kinetics and structural stability for energy storage is largely unknown. Herein, we report tin oxide-functionalized CCH surface-enabled unique two-dimensional (2D) interlayered heterostructures that promote high conductivity with more electroactive sites to maximize redox reactions. A simple electrodeposition technique was utilized to construct the hierarchical 2D CCH electrode, while a surface-reinforced method was employed to fabricate the 2D interlayered SnO on CCH.

Poly(amidoamine) Dendrimer as an Interfacial Dipole Modification in Crystalline Silicon Solar Cells.

Poly(amidoamine) (PAMAM) dendrimers are used to modify the interface of metal-semiconductor junctions. The large number of protonated amines contributes to the formation of a dipole layer, which finally serves to form electron-selective contacts in silicon heterojunction solar cells. By modification of the work function of the contacts, the addition of the PAMAM dendrimer interlayer quenches Fermi level pinning, thus creating an ohmic contact between the metal and the semiconductor.

Polymeric Interlayer in CdS-Free Electron-Selective Contact for SbSe Thin-Film Solar Cells.

High open-circuit voltage in SbSe thin-film solar cells is a key challenge in the development of earth-abundant photovoltaic devices. CdS selective layers have been used as the standard electron contact in this technology. Long-term scalability issues due to cadmium toxicity and environmental impact are of great concern.

Does SbSe Admit Nonstoichiometric Conditions? How Modifying the Overall Se Content Affects the Structural, Optical, and Optoelectronic Properties of SbSe Thin Films.

SbSe is a quasi-one-dimensional (1D) semiconductor, which has shown great promise in photovoltaics. However, its performance is currently limited by a high deficit. Therefore, it is necessary to explore new strategies to minimize the formation of intrinsic defects and thus unlock the absorber's whole potential.

Atomic layer deposition of vanadium oxide films for crystalline silicon solar cells.

Transition metal oxides (TMOs) are promising materials to develop selective contacts on high-efficiency crystalline silicon solar cells. Nevertheless, the standard deposition technique used for TMOs is thermal evaporation, which could add potential scalability problems to industrial photovoltaic fabrication processes. As an alternative, atomic layer deposition (ALD) is a thin film deposition technique already used for dielectric deposition in the semiconductor device industry that has a straightforward up scalable design.

Towards the Bisbenzothienocarbazole Core: A Route of Sulfurated Carbazole Derivatives with Assorted Optoelectronic Properties and Applications.

Ladder-type molecules, which possess an extended aromatic backbone, are particularly sought within the optoelectronic field. In view of the potential of the 14-bis[1]benzothieno[3,2-:2',3'-]carbazole core as a p-type semiconductor, herein we studied a set of two derivatives featuring a different alkylation patterning. The followed synthetic route, involving various sulfurated carbazole-based molecules, also resulted in a source of fluorophores with different emitting behaviors.

Influence of Co-Sputtered Ag:Al Ultra-Thin Layers in Transparent VO/Ag:Al/AZO Hole-Selective Electrodes for Silicon Solar Cells.

As optoelectronic devices continue to improve, control over film thickness has become crucial, especially in applications that require ultra-thin films. A variety of undesired effects may arise depending on the specific growth mechanism of each material, for instance a percolation threshold thickness is present in Volmer-Webber growth of materials such as silver. In this paper, we explore the introduction of aluminum in silver films as a mechanism to grow ultrathin metallic films of high transparency and low sheet resistance, suitable for many optoelectronic applications.

Transition-Metal Oxides for Kesterite Solar Cells Developed on Transparent Substrates.

Fabrication on transparent soda-lime glass/fluorine-doped tin oxide (FTO) substrates opens the way to advanced applications for kesterite solar cells such as semitransparent, bifacial, and tandem devices, which are key to the future of the PV market. However, the complex behavior of the p-kesterite/n-FTO back-interface potentially limits the power conversion efficiency of such devices. Overcoming this issue requires careful interface engineering.

Enhanced Chiral Sensing with Dielectric Nanoresonators.

Chiro-sensitive molecular detection is highly relevant as many biochemical compounds, the building blocks of life, are chiral. Optical chirality is conventionally detected through circular dichroism (CD) in the UV range, where molecules naturally absorb. Recently, plasmonics has been proposed as a way to boost the otherwise very weak CD signal and translate it to the visible/NIR range, where technology is friendlier.

Interface engineering and solid-state organization for triindole-based p-type organic thin-film transistors.

Inspired by the excellent device performance of triindole-based semiconductors in electronic and optoelectronic devices, the relationship between the solid-state organization and the charge-transporting properties of an easily accessible series of triindole derivatives is reported herein. The vacuum-evaporated organic thin-film transistors (OTFTs) exhibited a non ideal behaviour with a double slope in the saturation curves. Moreover, the treatment of the gate insulator of the OTFT device with either a self-assembled monolayer (SAM) or a polymer controls the molecular growth and the film morphology of the semiconducting layer, as shown by X-ray diffraction (XRD) analyses, atomic force microscopy (AFM) and theoretical calculations.

Reduction of Charge Traps and Stability Enhancement in Solution-Processed Organic Field-Effect Transistors Based on a Blended n-Type Semiconductor.

Solution-processed n-type organic field-effect transistors (OFETs) are essential elements for developing large-area, low-cost, and all organic logic/complementary circuits. Nonetheless, the development of air-stable n-type organic semiconductors (OSCs) lags behind their p-type counterparts. The trapping of electrons at the semiconductor-dielectric interface leads to a lower performance and operational stability.

Solid-state organization of n-type carbazole-based semiconductors for organic thin-film transistors.

The development of new organic semiconductors has been mainly led by the search for new π-conjugated cores, but recently the use of flexible side chains is attracting more and more attention to control the molecular packing and order in the solid state to improve the charge-transporting properties. In this work, the charge transport properties of a series of tricyanovinyl-substituted carbazole-based materials with different alkyl chain lengths have been investigated and correlated with the respective intermolecular interactions and molecular packings via X-ray diffraction (XRD) studies.

Intermittent chaos for ergodic light trapping in a photonic fiber plate.

Extracting the light trapped in a waveguide, or the opposite effect of trapping light in a thin region and guiding it perpendicular to its incident propagation direction, is essential for optimal energetic performance in illumination, display or light harvesting devices. Here we demonstrate that the paradoxical goal of letting as much light in or out while maintaining the wave effectively trapped can be achieved with a periodic array of interpenetrated fibers forming a photonic fiber plate. Photons entering perpendicular to that plate may be trapped in an intermittent chaotic trajectory, leading to an optically ergodic system.

HOMO stabilisation in π-extended dibenzotetrathiafulvalene derivatives for their application in organic field-effect transistors.

Three new organic semiconductors, in which either two methoxy units are directly linked to a dibenzotetrathiafulvalene (DB-TTF) central core and a 2,1,3-chalcogendiazole is fused on the one side, or four methoxy groups are linked to the DB-TTF, have been synthesised as active materials for organic field-effect transistors (OFETs). Their electrochemical behaviour, electronic absorption and fluorescence emission as well as photoinduced intramolecular charge transfer were studied. The electron-withdrawing 2,1,3-chalcogendiazole unit significantly affects the electronic properties of these semiconductors, lowering both the HOMO and LUMO energy levels and hence increasing the stability of the semiconducting material.

A compact tetrathiafulvalene-benzothiadiazole dyad and its highly symmetrical charge-transfer salt: ordered donor π-stacks closely bound to their acceptors.

A compact and planar donor-acceptor molecule 1 comprising tetrathiafulvalene (TTF) and benzothiadiazole (BTD) units has been synthesised and experimentally characterised by structural, optical, and electrochemical methods. Solution-processed and thermally evaporated thin films of 1 have also been explored as active materials in organic field-effect transistors (OFETs). For these devices, hole field-effect mobilities of μFE = (1.