Ferroelectric materials use both the pyroelectric effect and piezoelectric effect for energy conversion. A ferroelectric BaTiO3‐based pyro‐piezoelectric sensor system is demonstrated to detect temperature and pressure simultaneously. The voltage signal of the device is found to enhance with increasing temperature difference with a sensitivity of about 0.048 V °C−1 and with applied pressure with a sensitivity of about 0.044 V kPa−1. Moreover, no interference appears in the output voltage signals when piezoelectricity and pyroelectricity are conjuncted in the device. A novel 4 × 4 array sensor system is developed to sense real‐time temperature and pressure variations induced by a finger. This system has potential applications in machine intelligence and man–machine interaction.

BiFeO 3 (BFO) is a potentially important Pb-free ferroelectric with a narrow bandgap and is expected to become a novel photodetector. The photocurrent in BFO 3 strongly depends on the temperature but only a few studies have investigated in detail the relationships between photocurrent and temperature. Here, the temperature-dependent photocurrent and the corresponding photosensing properties of a Ag/BFO/indiumtin oxide (ITO) photodetector based on an optimized planar-structured electrode configuration are investigated. The photocurrent and responsivity of the BFO 3 -based photodetector can first be increased and then be decreased with increasing temperature. The largest photocurrent and responsivity can reach 51.5 µA and 6.56 × 10 −4 A W −1 at 66.1 °C, which is enhanced 126.3% as compared with that at room temperature. This may be caused by the temperature-modulated bandgap and barrier height in Ag/BFO/ITO device. This study clarifies the relationship between photosensing performance and the operating temperature of BFO-based photodetector and will push forward the application of ferroelectric materials in photoelectric field.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201906232. above mentioned solar cells, ferroelectric materials, which can exhibit abnormal photovoltaic effect evidencing by above bandgap photovoltage, have attracted much attention. [6][7][8][9][10] By contrast with traditional solar cells, the mechanism of the photovoltaic effect in ferroelectric materials is totally different. Moreover, the particular photovoltaic effect with ferroelectrics may have more chances to break the energy conversion limit in conventional solar cells. [11] Among the traditional ferroelectric materials, the photovoltaic properties of BiFeO 3 (BFO) films and single crystals are extensive studied because of its narrow bandgap near 2.7 eV. [12][13][14] Early investigations have been focused on the fundamental science attempting to explain the origins and working principles of ferroelectric photovoltaic effect as well as adoption of practical methods to improve the photovoltaic performances. Due to the appearance of different abnormal photovoltaic properties on BFO devices, four theories are proposed involving bulk photovoltaic effect, [15,16] domain wall theory, [17] Schottky-junction effect [18,19] and depolarization field effect. [20,21] In recent years, The largely reduced bandgap can cover the entire visible range, resulting in that a high power conversion efficiency of 8.1% has been achieved on Bi 2 FeCrO 6 thin film. [22] However, such a power conversion efficiency is still far below the commercialized Si-based solar cells (22%).Moreover, without being used as a solar cell aiming to generate large-scale electricity, ferroelectric devices with small-scale electricity generation can simultaneously be a photodetector to detect incident light. [23][24][25][26] As compared with the conventional battery-powered counterparts, the self-powered photodete...

Ferroelectric materials hold great promise toward next generation of optoelectronic devices because of their unique characteristics such as above‐bandgap photovoltage and polarization‐dependent photocurrent. But the relative low photocurrent value limits their potential applications in real devices. In order to improve the photovoltaic performance and detailed and systematic investigations about the role of temperature gradient on the photocurrent in indium tin oxide (ITO)/BiFeO3 (BFO)/ITO device under various temperature gradients across both sides are carried out. The observed results reveal an enhancement in photocurrent under applying different temperature gradients, which is mainly associated with light intensity. The applied temperature gradients induce interesting mechanisms under weak and strong lights. Due to the temperature gradient controlled photocurrent, the photosensing performance of ITO/BFO/ITO photodetector device with respect to 365 nm light can be strongly modulated. This presented strategy offers a feasible route for enhancing the photovoltaic performances of the BFO material based device, which offers the capability to push forward the practical applications of ferroelectric photovoltaic devices.