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The search for lead-free alternatives to Pb(Zr,Ti)O3 (PZT) piezoelectric ceramics has become a major topic in functional materials research due to legislation in many countries that restricts the use of lead alloys and compounds in commercial products. This article examines both the necessity for regulation and the impacts those regulations have created in the context of piezoelectric materials. It reviews the toxicity of lead, describes current legislation to control the spread of lead in the environment, and attempts to define the risks associated with the manufacture, use, and disposal of lead-based piezoelectric materials. The consequences of current legislation, both intended and unintended, are examined.

HighlightsUltrahigh energy storage density of ~ 13.8 J cm−3 and large efficiency of ~ 82.4% are achieved in high-entropy lead-free relaxor ferroelectrics via high-entropy strategy, realizing nearly ten times growth.Outstanding energy storage properties are attributed to the enhanced random field and breakdown field, decreased nanodomain sizes, strong multiple local distortions coexisting in-phase and anti-phase oxygen octahedron tilts.Evolution of energy storage performance and domain structure with the increase in configuration entropy is systematically revealed for the first time.Advanced lead-free energy storage ceramics play an indispensable role in next-generation pulse power capacitors market. Here, an ultrahigh energy storage density of ~ 13.8 J cm−3 and a large efficiency of ~ 82.4% are achieved in high-entropy lead-free relaxor ferroelectrics by increasing configuration entropy, named high-entropy strategy, realizing nearly ten times growth of energy storage density compared with low-entropy material. Evolution of energy storage performance and domain structure with increasing configuration entropy is systematically revealed for the first time. The achievement of excellent energy storage properties should be attributed to the enhanced random field, decreased nanodomain size, strong multiple local distortions, and improved breakdown field. Furthermore, the excellent frequency and fatigue stability as well as charge/discharge properties with superior thermal stability are also realized. The significantly enhanced comprehensive energy storage performance by increasing configuration entropy demonstrates that high entropy is an effective but convenient strategy to design new high-performance dielectrics, promoting the development of advanced capacitors .

HighlightsThe toxicity issue of lead-based halide perovskites hinders theirs large-scale commercial applications in solar cells.A variety of non- or low-toxic perovskite materials have been used for development of environmentally friendly lead-free perovskite solar cells, some of which show excellent optoelectronic properties and device performances.At present, more new lead-free perovskite materials with tunable optical and electrical properties are urgently required to design highly efficient and stable lead-free perovskite solar cells.The toxicity issue of lead hinders large-scale commercial production and photovoltaic field application of lead halide perovskites. Some novel non- or low-toxic perovskite materials have been explored for development of environmentally friendly lead-free perovskite solar cells (PSCs). This review studies the substitution of equivalent/heterovalent metals for Pb based on first-principles calculation, summarizes the theoretical basis of lead-free perovskites, and screens out some promising lead-free candidates with suitable bandgap, optical, and electrical properties. Then, it reports notable achievements for the experimental studies of lead-free perovskites to date, including the crystal structure and material bandgap for all of lead-free materials and photovoltaic performance and stability for corresponding devices. The review finally discusses challenges facing the successful development and commercialization of lead-free PSCs and predicts the prospect of lead-free PSCs in the future.

The field of lead-free piezoceramics, which aims to replace lead zirconate titanate (PZT) and related perovskite materials, has been vibrant for almost 15 years. Once the science in this field attained a certain stage of maturity, materials with properties better than PZT have appeared, and the first products are about to reach the marketplace. This article describes the three most promising lead-free piezoceramics currently under discussion to replace PZT. Each has a pronounced property profile geared for specific applications. Guidelines for directions for fundamental future research on as well as technology transfer to industry of lead-free piezoceramics are provided.

Lead‐based halide perovskites have received great attention in light‐emitting applications due to their excellent properties, including high photoluminescence quantum yield (PLQY), tunable emission wavelength, and facile solution preparation. In spite of excellent characteristics, the presence of toxic element lead directly obstructs their further commercial development. Hence, exploiting lead‐free halide perovskite materials with superior properties is urgent and necessary. In this review, the deep‐seated reasons that benefit light emission for halide perovskites, which help to develop lead‐free halide perovskites with excellent performance, are first emphasized. Recent advances in lead‐free halide perovskite materials (single crystals, thin films, and nanocrystals with different dimensionalities) from synthesis, crystal structures, optical and optoelectronic properties to applications are then systematically summarized. In particular, phosphor‐converted LEDs and electroluminescent LEDs using lead‐free halide perovskites are fully examined. Ultimately, based on current development of lead‐free halide perovskites, the future directions of lead‐free halide perovskites in terms of materials and light‐emitting devices are discussed. The fundamental reasons for efficient emission of halide perovskites are investigated, which is helpful to get efficient light emission of lead‐free halide perovskites. The synthesis, crystal structure, optical and optoelectronic properties of different molecular dimensional lead‐free halide perovskites with different forms are then systematically reviewed. Finally, the applications of light‐emitting devices (phosphor‐converted LEDs and electroluminescent LEDs) are discussed.

Recently, lead‐free double perovskites have emerged as a promising environmentally friendly photovoltaic material for their intrinsic thermodynamic stability, appropriate bandgaps, small carrier effective masses, and low exciton binding energies. However, currently no solar cell based on these double perovskites has been reported, due to the challenge in film processing. Herein, a first lead‐free double perovskite planar heterojunction solar cell with a high quality Cs2AgBiBr6 film, fabricated by low‐pressure assisted solution processing under ambient conditions, is reported. The device presents a best power conversion efficiency of 1.44%. The preliminary efficiency and the high stability under ambient condition without encapsulation, together with the high film quality with simple processing, demonstrate promise for lead‐free perovskite solar cells. A high‐quality double perovskite Cs2AgBiBr6 film is successfully demonstrated using a low‐pressure assisted solution method. A planar heterojunction solar cell based on this Cs2AgBiBr6 film shows high stability with an optimal power conversion efficiency of 1.44%. The preliminary results are promising for the development lead‐free perovskite solar cells.

HighlightsRecent progress of efficiency and long-term stability for perovskite solar cells, and the development of perovskite-based tandem solar cells are described.The progress of lead-free perovskite solar cells and their potential for industrial production are discussed in detail.The current status, ongoing challenges, and the future outlooks of perovskite solar cells are highlighted.Perovskite solar cells (PSCs) emerging as a promising photovoltaic technology with high efficiency and low manufacturing cost have attracted the attention from all over the world. Both the efficiency and stability of PSCs have increased steadily in recent years, and the research on reducing lead leakage and developing eco-friendly lead-free perovskites pushes forward the commercialization of PSCs step by step. This review summarizes the main progress of PSCs in 2020 and 2021 from the aspects of efficiency, stability, perovskite-based tandem devices, and lead-free PSCs. Moreover, a brief discussion on the development of PSC modules and its challenges toward practical application is provided.

Methylammonium bismuth (III) iodide single crystals and films have been developed and investigated. We have further presented the first demonstration of using this organic–inorganic bismuth-based material to replace lead/tin-based perovskite materials in solution-processable solar cells. The organic–inorganic bismuth-based material has advantages of non-toxicity, ambient stability, and low-temperature solution-processability, which provides a promising solution to address the toxicity and stability challenges in organolead- and organotin-based perovskite solar cells. We also demonstrated that trivalent metal cation-based organic–inorganic hybrid materials can exhibit photovoltaic effect, which may inspire more research work on developing and applying organic-inorganic hybrid materials beyond divalent metal cations (Pb (II) and Sn (II)) for solar energy applications.

The growing demand for high-power-density electric and electronic systems has encouraged the development of energy-storage capacitors with attributes such as high energy density, high capacitance density, high voltage and frequency, low weight, high-temperature operability, and environmental friendliness. Compared with their electrolytic and film counterparts, energy-storage multilayer ceramic capacitors (MLCCs) stand out for their extremely low equivalent series resistance and equivalent series inductance, high current handling capability, and high-temperature stability. These characteristics are important for applications including fast-switching third-generation wide-bandgap semiconductors in electric vehicles, 5G base stations, clean energy generation, and smart grids. There have been numerous reports on state-of-the-art MLCC energy-storage solutions. However, lead-free capacitors generally have a low-energy density, and high-energy density capacitors frequently contain lead, which is a key issue that hinders their broad application. In this review, we present perspectives and challenges for lead-free energy-storage MLCCs. Initially, the energy-storage mechanism and device characterization are introduced; then, dielectric ceramics for energy-storage applications with aspects of composition and structural optimization are summarized. Progress on state-of-the-art energy-storage MLCCs is discussed after elaboration of the fabrication process and structural design of the electrode. Emerging applications of energy-storage MLCCs are then discussed in terms of advanced pulsed power sources and high-density power converters from a theoretical and technological point of view. Finally, the challenges and future prospects for industrialization of lab-scale lead-free energy-storage MLCCs are discussed.

Electronic products are evolving towards miniaturization, high integration, and multi-function, which undoubtedly puts forward higher requirements for the reliability of solder joints in electronic packaging. Approximately 70% of failure in electronic devices originates during the packaging process, mostly due to the failure of solder joints. With the improvement of environmental protection awareness, lead-free solder joints have become a hot issue in recent years. This paper reviews the research progress on the reliability of lead-free solder joints and discusses the influence of temperature, vibration, tin whisker and electromigration on the reliability of solder joints. In addition, the measures to improve the reliability of solder joints are analyzed according to the problems of solder joints themselves, which provides a further theoretical basis for the study of the reliability of solder joints of electronic products in service.