Variation of iodide/bromide ratio in perovskite films and devices for the use in tandem solar cells
We have developed a fabrication route for perovskite films that allow substantial changes in the band gap of the semiconductor, by simply changing the iodide/bromide ratio in the precursor solution. A detailed analysis of various compositions of the photo absorber can provide further insights of efficiency limiting phenomena. Additionally, investigation of alternative hole transporting layers can reveal information about perovskite crystal growth and trap state formation. An automated process reduces the fabrication time for a large number of samples, which are essential for detailed analysis of phenomena like mentioned before.
Status: Ongoing
Date of proposal: 01/12/2021
Start date: 25/07/2022
End Date: 29/07/2022
Used Instruments: Avantes AvaSpec ULS2048CL UV-VIS spectrometer. Coherent Obis LX 405 nm laser. Andor CD420A-OE CCD sensor.
Experimental Technique: Photoluminescence spectroscopy. Solvent ratio optimization. Spin coating. Annealing.
Experiment Description: Investigation of photoinduced phase segregation in Cs0.2FA0.8Pb(I0.5Br0.5)3 films. Focus on optimizing solvent and perovskite precursor composition, spin coating parameters, and thiourea additive concentration.
Type Samples: Cs0.2FA0.8Pb(I0.5Br0.5)3 perovskite films.
Sample Description: Perovskite films prepared with varying solvent ratios, additive concentrations, and spin coating parameters.
Experiment Data Type: Photoluminescence measurements. Variations in film properties based on experimental conditions.
Characterization Technics: Photoluminescence spectroscopy for phase segregation analysis. Comparative analysis of film properties under different processing conditions.
Characterization Data Type: Photoluminescence response of perovskite films under different fabrication conditions. Phase segregation characteristics.
Analyzed Data: Influence of changing solvent ratios and additive concentrations on phase segregation. Effect of fabrication parameters on film stability and photoluminescence properties.
Main Targets Project: Reproducing and optimizing a recipe for wide bandgap perovskite solar cells with minimal phase segregation. Understanding the impact of fabrication parameters on the stability of the perovskite films.
Main Achievements Findings: Inability to reproduce the stability of films as claimed in the literature. Preliminary findings suggest that none of the films showed stability during extended illumination. Further investigation required for optimizing spin coating parameters and additive concentrations.