Synergistic Solar-Driven Freshwater Generation and Electricity Output Empowered by Wafer-Scale Nanostructured Silicon.

Electricity generation triggered by the ubiquitous water evaporation process provides an intriguing way to harvest energy from water. Meanwhile, natural water evaporation is also a fundamental way to obtain fresh water for human beings. Here, a wafer-scale nanostructured silicon-based device that takes advantage of its well-aligned configuration that simultaneously realizes solar steam generation (SSG) for freshwater collection and hydrovoltaic effect generation for electricity output is developed. An ingenious porous, black carbon nanotube fabric (CNF) electrode endows the device with sustainable water self-pumping capability, excellent durable conductivity, and intense solar spectrum harvesting. A combined device based on the CNF electrode integrated with nanostructured silicon nanowire arrays (SiNWs) provided an aligned numerous surface-to-volume water evaporation interface that enables a recorded continuous short-circuit current 8.65 mA and a water evaporation rate of 1.31 kg m-2 h-1 under one sun illumination. Such wafer-scale SiNWs-based SSG and hydrovoltaic integration devices would unchain the bottleneck of the weak and discontinuous electrical output of hydrovoltaic devices, which inspires other sorts of semiconductor-based hydrovoltaic device designs to target superior performance.

Synergistic Effect of Dielectric Property and Energy Transfer on Charge Separation in Non-Fullerene-Based Solar Cells.

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.

Mask-Free Patterned Perovskite Microcavity Arrays via Inkjet Printing Targeting Laser Emission.

Perovskite materials are promising candidates for the implementation of electrically pumped lasers considering the enhanced performance of perovskite-based light-emitting diodes. Nonetheless, current methods of fabricating perovskite optical microcavities require complex patterning technologies to build suitable resonant cavities for perovskite laser emission, burdening the device structure design. To address this issue, we applied inkjet printing, a maskless patterning technique, to directly create spontaneous formations of polycrystalline perovskite microcavity arrays to explore their laser-emitting action. The substrate surface tension was tuned to modulate the perovskite crystallization process in combination with optimization of printing ink recipes. As a result, polycrystalline perovskite microcavity arrays were achieved, contributing to the laser emission at 528 nm with a lasing threshold of 1.37 mJ/cm2, while simultaneously achieving high-definition patterning of flexible display. These results clearly illustrate the efficiency of inkjet printing technology in the preparation of polycrystalline perovskite optical microcavities and promote the development of flexible laser arrayed displays, providing a facile process toward the realization of perovskite-cavity laser devices.

All-In-One Evaporators for Efficient Solar-Driven Simultaneous Collection of Water and Electricity.

The shortage of fossil fuels and freshwater resources has become a serious global issue. Using solar energy to extract clean water with a photothermal conversion technology is a green and sustainable desalination method. Integrated electricity generation during the desalination process maximizes energy utilization efficiency. Herein, a solar-driven steam and electricity generation (SSEG) system based on an all-in-one evaporator is prepared via a scalable technology. Carbon black is selected as the absorber for solar energy harvesting as well as the functional substance for simultaneous electricity generation. Fabric substrate with flexible structure, porous channel, and capillary effect is vital for directional brine supply, multiple solar absorption, and thermal management. The high evaporation rate (1.87 kg m-2  h-1 ) and voltage output (324 mV) can be achieved with an all-in-one device. The stable electricity output can be maintained over 40000 s. The SSEG performance remains constant after 15 operation cycles or 20 wash cycles. The integrated device balances excellent effectiveness and practicality, providing a viable path for clean desalination and electricity generation.

A Hygroscopic Janus Heterojunction for Continuous Moisture-Triggered Electricity Generators.

Moisture-triggered electricity generator (MEG) harvesting energy from the ubiquity of atmospheric moisture is one of the promising potential candidates for renewable power demand. However, MEG device performance is strongly dependent on the moisture concentration, which results in its large fluctuation of the electrical output. Here, a Janus heterojunction MEG device consisting of nanostructured silicon and hygroscopic polyelectrolyte incorporating hydrophilic carbon nanotube mesh is proposed to enable ambient moisture harvesting and continuous stable electrical output delivery. The nanostructured silicon with a large surface/volume ratio provides strong coupling interaction with water molecules for charge generation. A polyelectrolyte of polydiallyl dimethylammonium chloride (PDDA) can facilitate charge selective transporting and enhance the effectiveness of moisture-absorbing in an arid environment simultaneously. The conductive, porous, and hydrophilic carbon nanotube mesh allows water to be ripped through as well as the generated charges being collected timely. As such, any generated charge carriers in the Janus heterojunction can be efficiently swept toward their respective electrodes, because of the device asymmetric contact. A MEG device continuously delivers an open-circuit voltage of 1.0 V, short-circuit current density of 8.2 µA/cm2, and output power density of 2.2 µW/cm2 under an ambient environment (60% relative humidity, 25 °C), which is a record value over the previously reported values. Furthermore, the infrared thermal measurements also reveal that the moisture-triggered electricity generation power is likely ascribed to surrounding thermal energy collected by the MEG device. Our results provide an insightful rationale for the design of device structure and understanding of the working mechanism of MEG, which is of great importance to promote the efficient electricity conversion induced by moisture in the atmosphere.

Asymmetric Charged Conductive Porous Films for Electricity Generation from Water Droplets via Capillary Infiltrating.

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 Ti3C2TX 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/cm2 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 high-efficiency hydrovoltaic devices with a large current density.

Bioinspired Hierarchical Nanofabric Electrode for Silicon Hydrovoltaic Device with Record Power Output.

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 (Voc) of 550 mV and a short-current density (Jsc) 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.