WP1 was fully dedicated to the technical developments of the project. Below the description of the activities/steps performed:
Step 1: Sputtering system and target preparation.
The first stage of the project was dedicated to the acquisition and installation of the sputtering setup dedicated to halide materials. After the system was acquired, it also needed to be installed inside a glovebox, which caused delays in the installation. By month 9, the system started to be operational. Following this, the development and preparation of targets followed.
Development was needed due to the larger target sizes required for the new sputtering setup. Developments included:
1. Power to ball ratio during ball milling of the powders
2. Uniaxial press force to form a dense target
3. Target bonding to metal backing plate
Once these parameters were defined, the first depositions were tested.
Step 2: Sputtering of inorganic halide materials. PbI2 and CuI targets were prepared and tested with various sputtering deposition parameters (RF power, power ramping rate, working pressure, sputtering time). Challenges included the de-bonding of the target due to not efficient cooling or fast ramping of the sputtering power. Several optimization rounds were performed to find the optimum range of high enough deposition rate and integrity of the target. The targets and films deposited were characterized by X-ray diffractiomn, XPS and EDX.
Step 3: After the first films were optimized, the PbI2 based films were converted to perovskite via the hybrid method. The hybrid approach delivered comparable results with either the inorganic layer fabricated via sputtering deposition or via pulsed laser deposition in terms of material quality. By the end of the project, the optimization of the solar cells continue up to date and follow up project proposals with device partners are in preparation.
