A novel breakthrough in making nontoxic halide perovskites as solar cell materials were considered in the journal ACS Omega. Since the introduction of organic–inorganic perovskites with ABX3 stoichiometry in 2009, there has been tremendous progress in imagining effective solar cell materials around the world, both theoretically and experimentally.
Study: Recent Advancements in Nontoxic Halide Perovskites: Beyond Divalent Composition Space.Image Credit: Iaremenko Sergii/Shutterstock.com
Despite achieving 25.5 percent efficiency, hybrid halide perovskites still face two major challenges: lead toxic effects and device instability.
Stoichiometries have arisen to overcome these two major issues that have hampered solar energy collecting progress. Several experiments, both practical and theoretical, are being done to discover the holy-grail materials that might be ideal for PV technology that is not only effective but also stable and nontoxic.
However, with such solar energy materials, the trade-off between stability, efficiency, and toxicity has yet to be fully resolved, necessitating a thorough review of A3B2X9- and A2MM′X6-based photovoltaic materials.
Solar Energy as the Answer to Worldwide Energy Needs
The development of a country is closely related to energy generation, management, and intelligent utilization. Most nations now rely on traditional energy sources, which will run out very soon, resulting in an energy shortage. Overconsumption, overcrowding, bad management, and a lack of knowledge have all contributed to the current energy crisis.
The greatest problem facing the science community is solving the energy crisis. To solve the current energy predicament, focused development on nonconventional, affordable, and, most critically, renewable energy sources are required. Among all emerging renewable energy, photovoltaic is the most attractive. Solar energy has numerous advantages over some other types of renewable energy, including ease of gathering, relative cleanliness, little maintenance, and cost-effectiveness.
Perovskite as an Attractive Photovoltaic Source
The mineral composition of perovskite is really great for solar cells. Perovskite mineral does have the capability of absorbing light and uses less than 1 m of material to capture the same amount of sunlight as other solar panels. Perovskite is a semiconductor that is utilized to carry electric charges when light strikes it.
Perovskite solar cells operate in the same way as regular solar panels: a semiconductor captures solar energy and generates a flow of electrons, which is caught by wire and transformed into useful electricity.
PSCs have stability problems when presented to ambient weather systems, despite their high conversion efficiency. Since perovskites collapse readily, they have such a shorter lifetime than silicon solar cells. The existence of oxygen and moisture in the environment causes structural instability.
The molecule of water becomes entrapped in the perovskite and serves as a catalyst for structural deterioration. Perovskites are also extremely susceptible to high temperatures; once the temperature above 100 °C, deterioration ensues. Temperatures exceeding 85 °C should be tolerated by a stable perovskite.
Perovskites Synthesis to be Nontoxic
These perovskites polymers have shown excellent resistivities. Various synthesis approaches, such as single-step spin-coating, layered-solution crystallization, two-step soaking-assisted method, and so on. Perovskite materials' space groups and direct or indirect band gaps are important deciding criteria.
Considering the Chemical Evolution of Perovskite Inks
Researchers also talked about some of the constraints (toxicity, large bandgap, instability, and so on) and how to overcome them. The search for a more stable and less hazardous alternative has paved the way for trivalent and tetravalent metal substitutions. Perovskites based on Sb and Bi can be used to create them.
In the field of solar technology, antimony (Sb)-based perovskite materials with strong optoelectronic capabilities, exceptional stability, and low toxicity have a bright future. Along with positive characteristics, there are also drawbacks, such as a large bandgap, uncontrolled crystallization, poor structural properties, and a water-sensitive character. They have an unfavorable exciton binding energy and a short exciton diffusion length.
The Benefit of Using Perovskites Photovoltaic
Sb-based perovskites have a bandgap ranging from 1.95 to 2.43 eV, that can be adjusted by including a less-toxic element into the perovskite structure. The inclusion of novel antisolvents has the potential to influence the crystallization process and, as a result, the structural characteristics.
The incorporation of hydrophobic cations into the perovskite structure may aid in the improvement of the water sensitivities of Sn-based perovskites. Perovskites based on Ag–Bi materials have a wide indirect bandgap, which limits the photovoltaic effectiveness.
Band-gap engineering, such as alloying or doping, can be used to reduce the optical band gap; for example, the bandgap of Cs2TiBr6 can be adjusted by replacing different materials; to decrease the bandgap, Cu, Sb, and Tl can be doped; to increase the bandgap, In can be used as a dopant.
New Research in this Field
FA4GeSbCl12 is a novel double perovskite with a bandgap of 1.3 eV. Using compositional engineering, distinct perovskite characteristics can be maximized, breaking free from stereotypes. The field of double perovskites is both demanding and exciting. The majority of the features remain unexplored and must be thoroughly investigated in order to propel the research age into a new era.
Kumar, D., et al. (2021). Recent Advancements in Nontoxic Halide Perovskites: Beyond Divalent Composition Space. ACS Omega. Publication Date: November 29, 2021 https://pubs.acs.org/doi/10.1021/acsomega.1c05333