Hybrid organic–inorganic perovskites have shown exceptional semiconducting properties and microstructural versatility for inexpensive, solution‐processable photovoltaic and optoelectronic devices. In this work, an all‐solution‐based technique in ambient environment for highly sensitive and high‐speed flexible photodetectors using high crystal quality perovskite nanowires grown on Kapton substrate is presented. At 10 V, the optimized photodetector exhibits a responsivity as high as 0.62 A W−1, a maximum specific detectivity of 7.3 × 1012 cm Hz1/2 W−1, and a rise time of 227.2 µs. It also shows remarkable photocurrent stability even beyond 5000 bending cycles. Moreover, a deposition of poly(methyl methacrylate) (PMMA) as a protective layer on the perovskite yields significantly better stability under ambient air operation: the PMMA‐protected devices are stable for over 30 days. This work demonstrates a cost‐effective fabrication technique for high‐performance flexible photodetectors and opens opportunities for research advancements in broadband and large‐scale flexible perovskite‐based optoelectronic devices.

Colloidal perovskite nanocrystals (PNCs) combine the outstanding optoelectronic properties of bulk perovskites with strong quantum confinement effects at the nanoscale. Their facile and low‐cost synthesis, together with superior photoluminescence quantum yields and exceptional optical versatility, make PNCs promising candidates for next‐generation optoelectronics. However, this field is still in its early infancy and not yet ready for commercialization due to several open challenges to be addressed, such as toxicity and stability. Here, the key synthesis strategies and the tunable optical properties of PNCs are discussed. The photophysical underpinnings of PNCs, in correlation with recent developments of PNC‐based optoelectronic devices, are especially highlighted. The final goal is to outline a theoretical scaffold for the design of high‐performance devices that can at the same time address the commercialization challenges of PNC‐based technology.

Ferroelectric materials may be used as effective photoelectrocatalysts for water splitting due to enhanced charge carrier separation driven by their spontaneous polarization induced internal electric field. Compared to other ferroelectric materials, BiFeO3 exhibits a high catalytic efficiency due to its comparatively smaller bandgap, which enables light absorption from a large part of the solar spectrum and its higher bulk ferroelectric polarization. Here, we compare the photoelectrochemical properties of three different BiFeO3 morphologies, namely, nanofibers, nanowebs, and thin films synthesized via electrospinning, directly on fluorine-doped tin oxide (FTO) coated glass substrates. A significant photocathodic current in the range from −86.2 to −56.5 μA cm−2 at −0.4 V bias (vs Ag/AgCl) has been recorded for all three morphologies in 0.1M Na2SO4 aqueous solution (pH = 6.8). Among these morphologies, BiFeO3 nanofibers exhibit higher efficiency because of their larger surface area and improved charge separation resulting from rapid diffusion of photoinduced charge carriers along the axis of the nanofiber. In the case of BiFeO3 nanofibers, we obtained the highest photocurrent density of −86.2 µA/cm2 at −0.4 V bias (vs Ag/AgCl electrode) and an onset potential of 0.22 V. We also observed that the onset potential of the photocathodic current can be increased by applying a positive polarization voltage, which leads to favorable bending of band edges at the electrode/electrolyte interface resulting in increased charge carrier separation.

We report on electrospinning-assisted fabrication of highly efficient and reusable BiFeO 3 nanofiber-based membranes for photo-activated organic pollutant removal with negligible colloidal release. For validation purposes, we exploit a fluorescent rhodamine B (RhB)-doped solution photo-degraded using visible and infrared illumination (λ ≥ 400 nm) from a solar simulator. As such, pollutant degradation can be directly monitored in real time. Fabrication yields an outstanding control of the fibers' morphology, and metal-enhanced photocatalytic properties are achieved by coating the nanofiber membranes with few nanometers of platinum using sputtering technique. This chemical-free functionalization of the nanofibers allows rapid and efficient RhB degradation. After optimization, 2.4 mg of photocatalyst achieves 93% removal after 150 min under solar illumination, which is impressively more efficient compared with previous reports. Most importantly, the colloidal release-free photocatalysis activity coupled to a manufacturing-ready fabrication process makes it ideal for large-scale deployment using industrial grade equipment.

In this study, serigraphic-grade BiFeO3-based ink formulations are produced and then mixed with graphene to enhance the performances of screen-printed thermistor devices. The devices are printed atop a standard thermally boosted glass-reinforced epoxy (FR-4) substrate coated with interdigitated gold electrodes. The broader operating temperature range of these thermistors makes them compatible with standard printed circuit board (PCB) manufacturing and operating conditions. Thus, we achieve highly sensitive devices with a temperature coefficient of resistance (TCR) of −0.96%/°C, which is the highest sensitivity reported yet for any graphene-based thermistor operating from 25 to 170 °C. The best-performing devices are loaded with 3.5 wt % graphene. These low-hysteresis and stable thermistors boast a thermal index (β-coefficient) of 864 K. This optimal graphene loading occurs just above the percolation threshold.