Filterless Visible‐Range Color Sensing and Wavelength‐Selective Photodetection Based on Barium/Nickel Codoped Bandgap‐Engineered Potassium Sodium Niobate Ferroelectric Ceramics

Abstract

Photosensors, photodetectors, or color sensors are key components for various optical and optoelectronic applications. Semiconductor‐based photodetection has been a dominator which is excellent at measuring the photon intensity of incident light. However, the wavelength of the incident light to be measured must be known beforehand and it mostly depends on auxiliary methods to filter unknown wavelengths. Herein, an alternative but simple mechanism that is using a monolithic, bandgap‐engineered photoferroelectric ceramic to blindly determine the wavelength and intensity of incident light at the same time is demonstrated. The photoferroelectric compound is Ba‐ and Ni‐codoped (K,Na)NbO3 exhibiting a direct bandgap of ≈2 eV and a spontaneous polarization of ≈0.25 C m−2. The band–band charge carrier transition is confirmed by multiple characterization methods of photoluminescence, photodielectric spectroscopy, and photoconductivity. The existent optoelectrical cumulative effect enabled by the simultaneous narrow bandgap and strong ferroelectricity allows to reliably distinguish the wavelengths of 405, 552, and 660 nm as well as the power density ranging from ≈0.1 to 10 W cm−2, with the photoresponsivity of up to 60 μA W−1. Consequently, this work proposes an alternative to semiconductor‐based counterparts for filterless, wavelength‐selective photodetection and color sensing.

Ultrahigh Bulk Photovoltaic Effect Responsivity in Thin Films: Unexpected Behavior in a Classic Ferroelectric Material

“…Furthermore, our results suggest that a film with a polarization gradient through the entire film thickness may exhibit a high PCE. In such a film, deviation from periodicity is obtained throughout the film rather than only in the vicinity of the FEelectrode interface, so that the ultrahigh-BPE hot-carrier scattering effect will enable photocurrent generation even in the region far from the film-electrode interface, allowing the use of thick films, which can achieve higher-than-bandgap V OC simply by increasing the film thickness due to the linear dependence of V OC on d. Aditionally, even with a V OC under the E g , PV devices based on BPE can be used for wavelength-sensitive photodetection [44] and for low-intensity light harvesting, due to the lack of dependence of PCE on light intensity. In theoretical research, further efforts are necessary to develop a microscopic, first-principles-based description of the strong BPE effect in thin films that incorporates the effect of the interface and enables first-principles calculations to provide guidance for further BPE device design efforts.…”

Development status of optical-electrical-magnetic high-flux coupling materials

“…This is the first device of its kind in the field of energy harvesting research that collects energy simultaneously from thermal, solar, and kinetic energy sources utilizing a single energy conversion material or component [63]. The device may be able to perform a variety of functions, such as multi-stimuli sensing, multi-source energy harvesting, and harvesting-sensing integration using just one material or component [64]. In applicable smart electronic devices and wireless sensor networks, such a single-material characteristic may render the usually recognized tradeoff of employing multifunctionality to design downsizing unnecessary.…”

Robust and Tunable Ferroelectricity in Ba/Co Codoped (K0.5Na0.5)NbO3 Ceramics

“…Their outstanding electrical properties make them promising for significant applications in energy harvesting, energy storage, information storage, and photoelectric detection, etc. [1][2][3][4][5][6] The electrical properties of KNN-based ceramic could be modulated by different methods such as texture sintering, chemical doping, domain engineering and compositing. [7,8] For example, Satio et al prepared KNNbased textured ceramics using the reactive template grain growth method and achieved excellent piezoelectric properties.…”