Coatings

Optoelectronic memristors show significant potential for neuromorphic computing but are often limited by high operating voltages. Here, we constructed a low-voltage Ag/CsPbBr₃/CDs/FTO photonic memristor by incorporating carbon dots (CDs) as a regulatory medium within the CsPbBr₃ perovskite layer. The CDs significantly enhanced memristive performance: their surface defect states and localized electric field regulation enabled stable conductive filament formation and rupture at low voltages. This yielded favorable operational characteristics, including low set/reset voltages (0.72 V/−0.60 V) and preliminary cycling endurance with state retention. Leveraging the device’s continuously tunable conductance, we successfully emulated key synaptic learning behaviors such as paired-pulse facilitation (PPF) and long-term potentiation/depression (LTP/LTD). Implementing its weight-updating characteristics in an artificial neural network (ANN) achieved 92.17% accuracy in handwritten digit classification. This work demonstrates the effective role of CDs in enabling low-voltage, high-performance perovskite photonic memristors, providing a viable strategy for developing low-power neuromorphic hardware.

The ecological-driven sustainability of plastic materials encounters a major challenge in eco-efficient mechanical recycling falling short of meeting the required quality and quantities of post-consumer recyclates (PCRs) in sensitive application areas demanded by regulatory authorities. Those toxicological residues of contaminants that remain after mechanical recycling restrict PCRs use in sensitive application areas. Addressing the integration of PCR into high-demand applications such as food contact materials, this work investigates a novel technology for PCR product use by an innovative migration barrier development pathway of Si-based plasma-enhanced chemical vapor deposition (PECVD) coatings on pre-contaminated polypropylene (PP) model PCR cups, developed with consideration of applicable regulatory frameworks, including European Food Safety Authority (EFSA) requirements for food contact materials. As a starting point for migration barrier development, suitable oxygen transmission rate (OTR) barrier coatings for PCR cups were reproduced and transferred on virgin and model PCR PP cups. The coating procedure consisted of a pretreatment, an applied organic adhesion interlayer SiOCH and an inorganic functional barrier layer SiO_x, where the functionality was related to the applied SiO_x layer based on the barrier efficiency. Therefore, SiO_x was varied in the migration barrier development to find a suitable process window and efficiently correlate the effects of process parameters on OTR before and after migration testing, mass loss of simulant and the reduction in migration of eight introduced contaminants in the model PCR cup using GC/MS. This work advanced the understanding of PECVD for migration barriers under regulatory frameworks and reduced PCR matrix complexity in the analysis during development using model PCR cups.

The durability of coatings is often evaluated by the impact of standardized weathering cycles. While such tests may yield well-differentiated damage patterns, they do not reveal which specific weathering parameters—particularly temperature, moisture, or radiation exposure—contributed to the formation of each observed damage type or to what extent. Consequently, it remains unclear (i) how exactly each individual formulation should be modified in order to optimize coating durability, and (ii) which of the tested coatings are particularly (or less) suitable for specific climatic conditions. In the present study, a testing concept is introduced that is primarily based on conducting single-parameter variants of the fluorescent weathering cycle according to DIN EN ISO 16474-3:A (P1). These variants were designed in such a way that, by comparing the weathering results obtained from sets of three color-identical topcoat systems, conclusions could be drawn regarding the aforementioned aspects (i) and (ii). Indeed, it was demonstrated that formulation modifications derived from the observed results led to a markedly improved weathering stability of the topcoat systems, particularly with respect to their previously identified weaknesses.