Periodic Reporting for period 1 - PEROPTO (Single Crystalline Halide Metal Perovskites Based Optoelectronics)
Berichtszeitraum: 2018-02-01 bis 2020-01-31
In this project, we are planned firstly tackle with synthetic obstacles obtaining those single crystals with tailored dimension, especially ultrathin large scale perovskite platelets, by either chemical solution process which takes advantage of template formed by specific metal oxide frame or functional surfactants, or spatial atmospheric atomic layer deposition process which requires an epitaxial growth by feeding specific precursor vapor of perovskite raw materials. With those materials in hand, various optoelectronic devices, especially solar cell as the initial attempt, will be constructed based on those synthesized large scale single-crystalline perovskite materials for a potential breakthrough of device performance, and characterized with advanced optical and electronic tools and techniques to correlate device performance with the nature of single crystalline perovskite materials.
1. Ultra thin perovskite platelet:
The method proposed is based on the synthesis of specific surfactants from their precursors alkyl ammonium salts and halide acid solution by chemical solution process. Different types of surfactants, basically block-copolymers with varied length of carbon chain and functional end group as well, could impede or guide growth of perovskite crystal at certain direction, such as dodecylammounium iodide (DOD) (Task 2.1) preferentially binds the halide ions of (001) facets and then results in platelet-like perovskite single crystals, while octadecylammonium iodide (OTD) (Task 2.2 in the proposal) selectively binds the halide ions of (110) or (1–10) crystal facets and thus impedes the growth of the two directions and gives rise to wire-like perovskite single crystals, as shown in Figure 1 of the technical report. The solubility of synthesized supramolecular surfactants in perovskite precursor solution will be further adjusted by anchoring different functional end group (Task 2.3). Further purification of surfactants is crucial and will be done by recrystallization or filtration (Task 2.4). Their structural and compositional characterization will be done by different techniques such as X-ray diffraction, NMR and electron microscopies (Task 2.5). The synthesized platelets are shown in Figure 2 of the technical report.
2. Bulk perovskite single crystals:
At the same time, we are also carrying out the experiments to synthesize bulk perovskite single crystals, as shown in Figure 3 of the technical report. The method of solvothermal method is adapted to grow bulk perovskite single crystals, which just utilize the solubility difference of perovskite materials in polar solvent under different temperature. Currently, the centimeter-size perovskite single crystals is prepared and will be analyzed by some optical and electrical facilities based in Cambridge.
This project is tackling with the synthetic challenges of single crystalline perovskite materials with controllable dimension and its integration with optoelectronic devices such as solar cell, LED and laser for potential breakthrough of device performance. This envisioned combined approach, as far as we know, is herein explored for the first time.
Currently, we are able to produce perovskite thin platelet with thickness about few tens nanometers to few micrometers, as shown in Figure 2, which will is currently applied to some optoelectronics devices such as filed effect transistors as shown in Figure 3, that may have interesting advance in its performance due to implantation of single crystalline perovskite