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Abstract

Lightweight and flexible self-charging power systems with synchronous energy harvesting and energy storage abilities are highly desired in the era of the internet of things and artificial intelligences, which can provide stable, sustainable, and autonomous power sources for ubiquitous, distributed, and low-power wearable electronics. However, there is a lack of comprehensive review and challenging discussion on the state-of-the-art of the triboelectric nanogenetor (TENG)-based self-charging power textiles, which have a great possibility to become the future energy autonomy power sources. Herein, the recent progress of the self-charging power textiles hybridizing fiber/fabric based TENGs and fiber/fabric shaped batteries/supercapacitors is comprehensively summarized from the aspect of textile structural designs. Based on the current research status, the key bottlenecks and brighter prospects of self-charging power textiles are also discussed in the end. It is hoped that the summary and prospect of the latest research of self-charging power textiles can help relevant researchers accurately grasp the research progress, focus on the key scientific and technological issues, and promote further research and practical application process.

With the growing market of wearable devices for smart sensing and personalized healthcare applications, energy storage devices that ensure stable power supply and can be constructed in flexible platforms have attracted tremendous research interests. A variety of active materials and fabrication strategies of flexible energy storage devices have been intensively studied in recent years, especially for integrated self-powered systems and biosensing. A series of materials and applications for flexible energy storage devices have been studied in recent years. In this review, the commonly adopted fabrication methods of flexible energy storage devices are introduced. Besides, recent advances in integrating these energy devices into flexible self-powered systems are presented. Furthermore, the applications of flexible energy storage devices for biosensing are summarized. Finally, the prospects and challenges of the self-powered sensing system for wearable electronics are discussed.

Flexible batteries are key component of wearable electronic devices. Based on the requirements of medical and primary safety of wearable energy storage devices, rechargeable aqueous zinc ion batteries (ZIBs) are promising portable candidates in virtue of its intrinsic safety, abundant storage and low cost. However, many inherent challenges have greatly hindered the development in flexible Zn-based energy storage devices, such as rigid current collector and/or metal anode, easily detached cathode materials and a relatively narrow voltage window of flexible electrolyte. Thus, overcoming these challenges and further developing flexible ZIBs are inevitable and imperative. This review summarizes the most advanced progress in designs and discusses of flexible electrode, electrolyte and the practical application of flexible ZIBs in different environments. We also exhibit the heart of the matter that current flexible ZIBs faces. Finally, some prospective approaches are proposed to address these key issues and point out the direction for the future development of flexible ZIBs.

Flexible solar cells are important photovoltaics (PV) technologies due to the reduced processing temperature, less material consumption and mechanical flexibility, thus they have promising applications for portable devices and building-integrated applications. However, the efficient harvesting of photons is the core hindrance towards efficient, flexible PV. Light management by nanostructures and nanomaterials has opened new pathways for sufficient solar energy harvesting. Nanostructures on top surfaces provide an efficient pathway for the propagation of light. Aside from suppressing incident light reflection, micro-structured back-reflectors reduce transmission via multiple reflections. Nanostructures themselves can be the absorber layer. Photovoltaics based on high-crystallinity nanostructured light absorbers demonstrate enhanced power conversion efficiency (PCE) and excellent mechanical flexibility. To acquire a deep understanding of the impacts of nanostructures, herein, a concise overview of the recent development in the design and application of nanostructures and nanomaterials for photovoltaics is summarized.

Perovskite solar cell has emerged as a promising candidate in flexible electronics due to its high mechanical flexibility, excellent optoelectronic properties, light weight and low cost. With the rapid development of the device structure and materials processing, the flexible perovskite solar cells (FPSCs) deliver 21.1% power conversion efficiency. This review introduces the latest developments in the efficiency and stability of FPSCs, including flexible substrates, carrier transport layers, perovskite films and electrodes. Some suggestions on how to further improve the efficiency, environmental and mechanical stability of FPSCs are provided. Specifically, we considered that to elevate the performance of FPSCs, it is crucial to substantially improve film quality of each functional layer, develop more boost encapsulation approach and explore flexible transparent electrodes with high conductivity, transmittance, low cost and expandable processability.

Flexible perovskite solar cells (FPSCs) are supposed to play an important role in the commercialization of perovskite solar cells due to their unique properties, such as high efficiency, thin thickness and being compatible with roll to roll (R2R) process for mass production. At present, deformable and lightweight FPSCs have been successfully prepared and applied as power supply by integrating with different wearable and portable electronics, which opens a niche market for photovoltaics. In this mini review, we will introduce the recent progress of FPSCs from the aspect of small-area flexible devices, R2R processed devices with large scale and emerging flexible cells with deformability and stretchability. Finally, conclusion and outlook are provided.

Recently, polymer solar cells developed very fast due to the application of non-fullerence acceptors. Substituting asymmetric small molecules for symmetric small molecule acceptors in the photoactive layer is a strategy to improve the performance of polymer solar cells. The asymmetric design of the molecule is very beneficial for exciton dissociation and charge transport and will also fine-tune the molecular energy level to adjust the open-circuit voltage (Voc) further. The influence on the absorption range and absorption intensity will cause the short-circuit current density (Jsc) to change, resulting in higher device performance. The effect on molecular aggregation and molecular stacking of asymmetric structures can directly change the microscopic morphology, phase separation size, and the active layer's crystallinity. Very recently, thanks to the ingenious design of active layer materials and the optimization of devices, asymmetric non-fullerene polymer solar cells (A-NF-PSCs) have achieved remarkable development. In this review, we have summarized the latest developments in asymmetric small molecule acceptors (A-NF-SMAs) with the acceptor–donor–acceptor (A–D–A) and/or acceptor–donor–acceptor–donor–acceptor (A–D–A–D–A) structures, and the advantages of asymmetric small molecules are explored from the aspects of charge transport, molecular energy level and active layer accumulation morphology.

The halide perovskite blue light emitting diodes (PeLEDs) attracted many researchers because of its fascinating optoelectrical properties. This review introduces the recent progress of blue PeLEDs which focuses on emissive layers and interlayers. The emissive layer covers three types of perovskite structures: perovskite nanocrystals (PeNCs), 2-dimensional (2D) and quasi-2D perovskites, and bulk (3D) perovskites. We will discuss about the remaining challenges of blue PeLEDs, such as limited performances, device instability issues, which should be solved for blue PeLEDs to realize next generation displays.

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