Opportunities and Challenges of Lead-Free Perovskite Optoelectronic Devices

The most efficient perovskite solar cells contain toxic lead (Pb), so it is critical to find a substitution for Pb. Recent potential candidates include Sn, Ge, and Bi. Recent optoelectronic applications of lead-free perovskites are discussed, including solar cells, light-emitting diodes, and photodetectors. Understanding the origin of the instability of lead-free perovskite solar cells and developing suitable mitigation strategies are critical challenges that must be addressed. Organic–inorganic hybrid halide lead-based perovskites have attracted tremendous attention as novel active materials in solar cells due to their superior optical and electrical properties, with power conversion efficiencies (PCEs) reaching 23.7%. However, the toxicity of Pb-based perovskite materials still hinders their commercialization. Therefore, finding alternative ions to lead in perovskite materials to form environmentally friendly materials is highly desirable. In this review, promising candidates as lead substitutes are presented and discussed as applied to perovskite solar cells (PSCs), light-emitting diodes (LEDs), and photodetectors. The fabrication processes and methods that could improve the stability of lead-free perovskite materials are also included. Our findings reveal the spectacular performance of lead-free perovskites. Moreover, the present status and future perspectives are also discussed. Organic–inorganic hybrid halide lead-based perovskites have attracted tremendous attention as novel active materials in solar cells due to their superior optical and electrical properties, with power conversion efficiencies (PCEs) reaching 23.7%. However, the toxicity of Pb-based perovskite materials still hinders their commercialization. Therefore, finding alternative ions to lead in perovskite materials to form environmentally friendly materials is highly desirable. In this review, promising candidates as lead substitutes are presented and discussed as applied to perovskite solar cells (PSCs), light-emitting diodes (LEDs), and photodetectors. The fabrication processes and methods that could improve the stability of lead-free perovskite materials are also included. Our findings reveal the spectacular performance of lead-free perovskites. Moreover, the present status and future perspectives are also discussed. in graphs of the electronic band structure of solids, the band gap generally refers to the energy difference (in electron volts) between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. It is the energy required to promote a valence electron bound to an atom to become a conduction electron, which is free to move within the crystal lattice and serve as a charge carrier to conduct electric current. In PSCs, the optical band gap determines what portion of the solar spectrum a photovoltaic cell absorbs. a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with holes, releasing energy in the form of photons. This effect is called electroluminescence. The color of the light is determined by the energy required for electrons to cross the band gap of the semiconductor. the electrical potential difference between two terminals of a device when disconnected from any circuit [1.Yin W.J. et al.Unique properties of halide perovskites as possible origins of the superior solar cell performance.Adv. Mater. 2014; 26: 4653-4658Crossref PubMed Scopus (1475) Google Scholar]. There is no external load connected and no external electric current flows between the terminals. Alternatively, the open-circuit voltage may be thought of as the voltage that must be applied to a solar cell or a battery to stop the current. a type of solar cell where the photovoltaic active layer is a perovskite-structured compound, most commonly a hybrid organic–inorganic lead or tin halide-based material. a sensor of light or other electromagnetic radiation. A photodetector has a p–n junction that converts light photons into current. The absorbed photons make electron–hole pairs in the depletion region. A solar cell is an example of a photodetector that converts some of the light energy absorbed into electrical energy. refers to the portion of energy in the form of sunlight that can be converted into electricity via photovoltaics. an indicator of the stability and distortion of crystal structures. It is usually used to describe the perovskite structure, whereby the tolerance factor can be used to calculate the compatibility of an ion with a crystal structure.