Molecular Design of Lead-Free Perovskite Solar Cells

Organolead-based perovskite solar cells promise to revolutionise low-cost solar energy production due to their high efficiency and ease of manufacture. Yet, the toxicity of Pb impedes its large-scale applications. Thus, it is urgent to explore environment-friendly substitutions for Pb while retaining the primary excellent performance. However, a lack of fundamental understanding of the issues regarding the stability, safety and solar conversion efficiency of lead-free light absorbers impedes their development. This project aims to advance the design of lead-free light absorbers for solar cells by using state-of-the-art computer modelling and innovative theoretical techniques to address these issues. The theoretical discoveries will be used to engineer key materials within perovskite solar cells at the atomic level to get desired functions. These developments will, in turn, enhance device design and facilitate the progress of new cost-effective solar-energy technology.

Principal investigator

Yun Wang
Magnifying glass

Area of science

Chemistry, Computational Materials Science

Systems used


Applications used

Partner Institution: Griffith University | Project Code: pawsey0259

The Challenge

In response to long-term environmental and energy-related crises driven by population growth, limited fossil resources, and climate change, scientists are currently looking for sustainable ways to produce renewable energies. Solar energy as an alternative energy source to fossil-fuel-based energy system has attracted great interest due to its renewability and environmental cleanliness. Recently, perovskite-based solar cells (PSCs), a type of DSCs utilizing organic/inorganic hybrid perovskites as light harvesters, have been demonstrated with a conversion efficiency approaching 22.1%, showing that low-cost and yet efficient PSCs could be a promising low-cost alternative to costly Si-based solar cells.
The key breakthrough in the PSCs concept lies in the use of organolead as light harvesters to generate exciton pairs under solar irradiation. However, lead compounds are very toxic and harmful to the environment. It has been reported that CH3NH3PbI3 in contact with polar solvents such as water can convert to PbI2, a carcinogen that is moderately water-soluble and whose use is banned in many countries. PbI2 is also employed during the synthesis of CH3NH3PbI3, which may cause safety concern during the process. Resolution of this issue determines whether PSCs can meet the stringent international norms for outdoor photovoltaic applications. So far, limited studies have been conducted to efficiently improve the efficiencies of Pb-free perovskite materials for PSCs. Therefore, a systematic theoretical analysis of the operating principles, impacts of working environments on the stability and performance of PSCs, and screening of possible non-toxic materials are scientifically interesting and practically important.

The Solution

To speed up the search on the functionalised high-production perovskite light harvesters, the in-depth understanding of the properties of light absorbers and the mechanism of charge transfer processes at the atomic level, will be required. The electronic structure of materials and the mechanisms of the charge transfer process can be fully recognized through state-of-the-art computational techniques, or ab initio methods. Since most of the computations with DFT, hybrid DFT and ab initio molecular dynamics (AIMD) methods with the consideration of spin-orbital coupling (SOC) are very time-consuming, the supercomputers with parallel capacities are required. Furthermore, the calculation with hybrid DFT and AIMD method to get correct electronic and dynamic information of systems are more time-consuming.

The Outcome

The DFT and AIMD calculations will be performed by using the Vienna ab initio Simulation Program (VASP), Car-Parrinello Molecular Dynamics (CPMD) and QUANTUM ESPRESSO (opEn-Source Package for Research in Electronic Structure, Simulation, and Optimization) programs; The hybrid DFT method has been included in VASP and QUANTUM ESPRESSO; and the TDDFT techniques will be employed by using CPMD. Since most of the above-mentioned computations are very time-consuming, the supercomputers with parallel capacities with large memory are required. And the Magnus supercomputer system is one of the biggest and best-maintained ones in Australia, and all the software have been installed in this supercomputer. Thus, access to the Magnus system can greatly help the success of this project.

List of Publications

Jessica Jein White, Junxian Liu, Yun Wang, “High-symmetry tin(II) iodides as promising light absorbers for solar cells: A theoretical prediction”, Computational Materials Science, 2019, 156, 246-251 (IF=2.3, the first author is an undergraduate student)

Hong Wei Qiao, Shuang Yang, Yun Wang, Xiao Chen, Tian Yu Wen, Li Juan Tang, Qilin Cheng, Yu Hou, Huijun Zhao, Hua Gui Yang, “A Gradient Heterostructure Based on Tolerance Factor in High‐Performance Perovskite Solar Cells with 0.84 Fill Factor” Advanced Materials 2019, 31 (5), 1804217 (IF=19.8)

Bin Liu, Yun Wang, HQ Peng, R Yang, Z Jiang, X Zhou, CS Lee, Huijun Zhao, Wenjun Zhang, “Iron Vacancies Induced Bifunctionality in Ultrathin Feroxyhyte Nanosheets for Overall Water Splitting” Advanced Materials, 2018, 1803144 (IF=19.8, co-first author)

Zhuangchai Lai, Apoorva Chaturvedi, Yun Wang, Thu Ha Tran, Xiaozhi Liu, Chaoliang Tan, Zhimin Luo, Bo Chen, Ying Huang, Gwang-Hyeon Nam, Zhicheng Zhang, Ye Chen, Zhaoning Hu, Bing Li, Shibo Xi, Qinghua Zhang, Yun Zong, Lin Gu, Christian Kloc, Yonghua Du, Hua Zhang, “Preparation of 1T’-Phase ReS2xSe2 (1-x)(x= 0-1) Nanodots for Highly Efficient Electrocatalytic Hydrogen Evolution Reaction”, Journal of the American Chemical Society, 2018, 140(27), 8563-8568 (IF=13.9, co-first author)

Qizhong Xiong, Yun Wang, Peng‐Fei Liu, Li‐Rong Zheng, Guozhong Wang, Hua‐Gui Yang, Po‐Keung Wong, Haimin Zhang, Huijun Zhao, “Cobalt Covalent Doping in MoS2 to Induce Bifunctionality of Overall Water Splitting”, Advanced Materials, 2018, 1801450 (IF=19.8)

Changhong Wang, Yun Wang, Hongchao Yang, Yejun Zhang, Huijun Zhao, Qiangbin Wang, “Revealing the Role of Electrocatalyst Crystal Structure on Oxygen Evolution Reaction with Nickel as an Example”, Small, 2018, 1802895 (IF=9.6)

Yun Wang, Xu Liu, Junxian Liu, Mohammad Al-Mamun, Alan Wee-Chung Liew, Huajie Yin, William Wen, Yu Lin Zhong, Porun Liu, Huijun Zhao, “Electrolyte Effect on Electrocatalytic Hydrogen Evolution Performance of One-Dimensional Cobalt–Dithiolene Metal-Organic Frameworks: A Theoretical Perspective”, ACS Applied Energy Materials, 2018, 1 (4), 1688-1694 (ACS new journal)

Le Zhang, Peng Fei Liu, Yu Hang Li, Meng Yang Zu, Xu Li, Zheng Jiang, Yun Wang, Huijun Zhao, Huagui Yang, “N‐modified NiO Surface for Superior Alkaline Hydrogen Evolution”, ChemSusChem, 2018, 11, 1020-1024 (IF=7.2)

Meng Yang Zu, Peng Fei Liu, Chongwu Wang, Yun Wang, Li Rong Zheng, Bo Zhang, Huijun Zhao, Hua Gui Yang, “Bimetallic Carbide as a Stable Hydrogen Evolution Catalyst in Harsh Acidic Water”, ACS Energy Letters, 2018,3 (1), 78-84 (IF=12.3)

Figure 1. High-symmetry SnI2 as a novel lead-free light absorber has been theoretically proposed for solar to electrical energy conversion.