Periodic Reporting for period 2 - CREATE (Crafting Complex Hybrid Materials for Sustainable Energy Conversion)
Reporting period: 2021-07-01 to 2022-12-31
With an unprecedented rise in solar cell efficiencies and ease of fabrication, hybrid lead halide perovskites have gained worldwide popularity. However, these materials still lack of long-term thermal and environmental stability. To tackle this, halide perovskites with increasingly complex compositions (containing more than 4 distinct components) and structural motifs have been widely proposed. However, controlled growth of these multi-compound hybrid materials in the thin film form remains a challenge. The CREATE research program tackles directly the scientific and technical challenges of the controlled growth of hybrid organic-inorganic materials by a fully versatile in-vacuum thin film deposition process. We are developing a pulsed dual laser deposition (PDLD) method that will allow the controlled, in-vacuum deposition of a large range of both organic and inorganic materials, and their mixture in any pre-determined ratio. To allow the controlled, vacuum-based deposition of a full breadth of hybrid organic-inorganic thin films, the PDLD method will use two independently tuned laser sources for both, the organic (IR laser) and inorganic (UV laser) deposition, all in one single vacuum system.
The overall goal of CREATE and the PDLD method is to achieve maximum versatility for hybrid materials screening and discovery, and maximum growth control to tailor film properties and study the role each component has in the overall optoelectronic properties of the films. This will enable new and optimised materials for solar cells and novel optoelectronic devices.
The overall goal of CREATE and the PDLD method is to achieve maximum versatility for hybrid materials screening and discovery, and maximum growth control to tailor film properties and study the role each component has in the overall optoelectronic properties of the films. This will enable new and optimised materials for solar cells and novel optoelectronic devices.
The project started in January 2020 with the method development, including the design, development and acquisition of the PDLD system (custom-made for us by TSST Demcon), followed by the system installation and the development of the first processes (2020-2021). The first half of the project was dedicated to the demonstration of halide perovskite thin film formation using only the UV laser (the common laser for pulsed laser deposition - PLD). PLD of inorganic halide perovskites was demonstrated for CsSnI3 and Cs2AgBiBr6, all Pb-free alternatives. These results demonstrated the capability of PLD for near-stoichiometric transfer of elements from a single solid target (source material) to the thin films. Moving on to halide perovskites widely used for solar cells, and using the same UV laser, we furthermore demonstrated that hybrid compositions such as MAPbI3 (with MA = CH3NH3) can be deposited by PLD as well. Currently we are also exploring mixed organic cation compositions such as MAXFA1-xPbI3 by PLD using a single source. Halide perovskite materials, such as MAPbI3 and MAXFA1-xPbI3 are currently being tested in solar cell devices using our newly developed facilities for device fabrication and characterization. Work on layered halide perovskites has just started. For this absolute control of both, the deposition with the UV laser (inorganic components) and the IR laser (organic components) will be critical. This will complete the PDLD method proposed by CREATE with the goal of achieving full versatility in hybrid thin film growth.
Progress beyond state of the art includes:
1. Fabrication of CsSnI3 with stable black orthorhombic phase and no Sn oxidation demonstrated with pulsed laser deposition (PLD).
2. First time demonstration of PLD of double perovskite Cs2AgBiBr6. PLD has demonstrated to be an unique method that allows stoichiometric transfer of the 4 elements from a Cs2AgBiBr6 target to a Cs2AgBiBr6 thin film.
3. PLD not only allowed the deposition of complex inorganic halide perovskites from a single source, but also of hybrid organic inorganic perovskite films with up to two different organic cations. This opens up the path to simplified process for solar cells and even future tandem devices.
Expected results until the end of the project include the development of the PDLD method, which will be a unique system worldwide. Both, PLD and PDLD, offer solutions beyond state of art on deposition methods of halide perovskites. PLD will offer scalability and simplified processing, and PDLD will offer full versatility in terms of composition and structural motifs.
1. Fabrication of CsSnI3 with stable black orthorhombic phase and no Sn oxidation demonstrated with pulsed laser deposition (PLD).
2. First time demonstration of PLD of double perovskite Cs2AgBiBr6. PLD has demonstrated to be an unique method that allows stoichiometric transfer of the 4 elements from a Cs2AgBiBr6 target to a Cs2AgBiBr6 thin film.
3. PLD not only allowed the deposition of complex inorganic halide perovskites from a single source, but also of hybrid organic inorganic perovskite films with up to two different organic cations. This opens up the path to simplified process for solar cells and even future tandem devices.
Expected results until the end of the project include the development of the PDLD method, which will be a unique system worldwide. Both, PLD and PDLD, offer solutions beyond state of art on deposition methods of halide perovskites. PLD will offer scalability and simplified processing, and PDLD will offer full versatility in terms of composition and structural motifs.