Perovskites are a class of crystalline materials with a common complex chemical structure. Lead-halide hybrid organic-inorganic perovskites have recently emerged as highly efficient optoelectronic materials. Such materials are being intensively investigated and developed for photovoltaics, photodetection, light-emitting diodes, and laser devices. Solar cells containing hybrid organic-inorganic perovskites have achieved over 20% certified efficiency.
Perovskites are most commonly synthesized by combining a metal salt (for example, a lead-based salt such as lead iodide) with an organic halide salt in a single step, by spin-coating from a solution of both salts, by co-evaporation, or by a two-step method of forming the metal salt film and subsequently exposing it to the organic halide. The existing fabrication methods suffer from high toxicity, complexity and high energy input.
We present a new method for the preparation of halide perovskites on a substrate for optoelectronic devices and solar cells, including tandem cells that produce higher voltages.
· Solar cells
· Other optoelectronic devices (e.g., photodetectors, light-emitting diodes, lasers)
· Reduced toxicity
· Simple and straight-forward fabrication method
· Excellent morphology control of the perovskites
Perovskites are crystalline materials with the formula ABX3, in which A and B are cations and X represents an anion. In hybrid organicinorganic perovskites (HOIPs), A is an organic cation, B is a metal cation, and X is a halide anion.
The synthesis of HOIPs usually involves the use of toxic metal salts (for example, lead iodide or lead acetate) and organic solvents (such as dimethylformamide). Additionally, the combination of a metal salt with several organic solvents, such as dimethylsulfoxide, increases the toxicity of the solution in use.
The new fabrication method utilizes a metal or a metal alloy and an organic halide salt. In the first step, a layer comprising one of the components is deposited on a substrate. Then, the deposited layer is treated with a solution or a vapor of the second component to form a halide HOIP on a solid surface. This method provides a direct conversion of an elemental metal or a metal alloy to a halide perovskite or a perovskite related material. The main advantage of the presented method is the reduced toxicity of the solution used in the process. Additionally, the metals (mainly lead) are much less toxic in terms of manufacturing than the salts of the same metals.