Search

Coupling together the ferroelectric, pyroelectric, and photovoltaic characteristics within a single material is a novel way to improve the performance of photodetectors. In this work, we take advantage of the triple multifunctionality shown by 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 (BCZT), as demonstrated in an Al/Si/SiOx/BCZT/ITO thin‐film device. The Si/SiOx acts as an n‐type layer to form a metal–ferroelectric–insulator–semiconductor heterostructure with the BCZT, and with Al and ITO as electrodes. The photo‐response of the device, with excitation from a violet laser (405 nm wavelength), is carefully investigated, and it is shown that the photodetector performance is invariant with the chopper frequency owing to the pyro‐phototronic effect, which corresponds to the coupling together of the pyroelectric and photovoltaic responses. However, the photodetector performance was significantly better than that of the devices operating based only on the pyro‐phototronic effect by a factor of 4, due to the presence of ferroelectricity in the system. Thus, after a poling voltage of −15 V, for a laser power density of 230 mW/cm2 and at a chopper frequency of 400 Hz, optimized responsivity, detectivity, and sensitivity values of 13.1 mA/W, 1.7 × 1010 Jones, and 26.9, respectively, are achieved. Furthermore, ultrafast rise and fall times of 2.4 and 1.5 µs, respectively, are obtained, which are 35,000 and 36,000 times faster rise and fall responses, respectively, than previous reports of devices with the ferro–pyro–phototronic effect. This is understood based on the much faster ferroelectric switching in ferroelectric thin films owing to the predominant 180° domains in a single direction out of plane. [ABSTRACT FROM AUTHOR]

Nanogels, due to their unique properties, have potential for promising applications in several fields. There is a growing interest in understanding which are the mechanisms controlling their properties, as those depend not only on composition but also on internal structure. In this work, dissipative particle dynamics simulations were applied to simulate the formation of nanogels from monodisperse end-functionalised polymer chains, with the cross-linking reaction modelled using a distance-based algorithm, including a reversible intermediate step. Nanogel properties are studied by calculating their swelling transition curves and structure properties, such as network defects and entanglement state. Various chain lengths, reaction schemes, nanogel in silico synthesis methods and solvent ratios are compared and discussed, showing how these factors influence the nanogel swelling behaviour and structure. Our results show that, in order to be compared with experiments, nanogel simulations should carefully consider processing parameters. [ABSTRACT FROM AUTHOR]