Direct
electricity generation from water flow/evaporation, coined
hydrovoltaic effect, has recently attracted intense interest as a
facile approach to harvest green energy from ubiquitous capillary
water flow or evaporation. However, the current hydrovoltaic device
is inferior in output power efficiency compared to other renewable
energy devices. Slow water evaporation rate and inefficient charge
collection at device electrodes are two fundamental drawbacks limiting
energy output efficiency. Here, we report a bioinspired hierarchical
porous fabric electrode that enables high water evaporation rate,
efficient charge collection, and rapid charge transport in nanostructured
silicon-based hydrovoltaic devices. Such an electrode can efficiently
collect charges generated in nanostructured silicon as well as induce
a prompt water evaporation rate. At room temperature, the device can
generate an open-circuit voltage (V
oc)
of 550 mV and a short-current density (J
sc) of 22 μA·cm–2. It can output a power
density over 10 μW·cm–2, which is 3 orders
of magnitude larger than all those reported for analogous hydrovoltaic
devices. Our results could supply an effective strategy for the development
of high-performance hydrovoltaic devices through optimizing electrode
structures.
Inkjet printing is a powerful technology for realizing high‐density pixelated perovskite light‐emitting diodes (PeLEDs). However, the coffee‐stain effect in the inkjet printing process often leads to uneven thickness and poor crystallization of printed perovskite features, which deteriorates the performance of PeLEDs. Here, a strategy is developed to suppress the coffee‐stain effect via enhancing Marangoni flow strength. An interfacial poly(vinylpyrrolidone) (PVP) layer is incorporated to tune the surface tension of the underlying hole transport layer (HTL) and enhance the perovskite crystallization. The substrate temperature is also carefully controlled to tune the printing solvent evaporation rate rationally. By optimizing the thickness of the PVP layer and the temperature of the printing stage, the coffee‐stain effect is dramatically restrained. In addition, the interfacial insulating PVP layers play a positive role in suppressing leakage current level of PeLEDs by avoiding any direct electrical contact between HTL and electron transporting layer. Finally, an inkjet‐printed PeLED with a brightness of 3640 cd m–2 and external quantum efficiency of 9.0% is achieved. This work highlights the availability of inkjet‐printing technology for fabricating patterned PeLEDs in information display applications.
Hydrovoltaic devices are proposed as an alternative way to directly generate electricity due to the ubiquity of water and its interaction with specific porous structures. At present, the output power density of the reported device is limited by its low current density arising from the low surface charge density and inferior charge transport capability of the active materials. In this work, an asymmetric structure consisting of positively charged conductive polyaniline (PANI) and negatively charged Ti 3 C 2 T X MXene is proposed to build a hydrovoltaic device to achieve high conductivity and surface charge density simultaneously. An extra polyvinyl alcohol layer is utilized between PANI and MXene to reserve the asymmetric structure and maintain a constant voltage output. As a result, a peak current density of 1.8 mA/cm 2 is achieved, which is 18 times higher than the previous peak current density of the device with an inert electrode. Our work of incorporating an asymmetric structure provides an alternative way to target highefficiency hydrovoltaic devices with a large current density.
In non‐fullerene‐based photovoltaic devices, it is unclear how excitons efficiently dissociate into charge carriers under small driving force. Here, we developed a modified method to estimate dielectric constants of PM6 donor and non‐fullerene acceptors. Surprisingly, most non‐fullerene acceptors and blend films showed higher dielectric constants. Moreover, they exhibited larger dielectric constants differences at the optical frequency. These results are likely bound to reduced exciton binding energy and bimolecular recombination. Besides, the overlap between the emission spectrum of donor and absorption spectra of non‐fullerene acceptors allowed the energy transfer from donor to acceptors. Hence, based on the synergistic effect of dielectric property and energy transfer resulting in efficient charge separation, our finding paves an alternative path to elucidate the physical working mechanism in non‐fullerene‐based photovoltaic devices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.