White light emission from lead-free mixed-cation doped Cs2SnCl6 nanocrystals

We have designed a synthesis procedure to obtain Cs2SnCl6 nanocrystals (NCs) doped with metal ion(s) to emit visible light.

Investigating the Sequential Deposition Route for Mixed Cation Mixed Halide Wide Bandgap Perovskite Absorber Layer

Wide bandgap (Eg) perovskite solar cells (PSCs) are emerging as the preferred choice for top cells in a tandem architecture with crystalline silicon solar cells. Among the wide bandgap perovskites, a mixed cation mixed halide composition containing CsyFA1-yPbI3−xBrx is a popular choice because the presence of bromine widens the bandgap and addition of cesium stabilizes the crystal structure. These perovskite layers are commonly fabricated using one-step spin coating technique; however, sequential spin coating followed by dip coating has been successful in offering better control over the crystallization process for low bandgap absorber layers. In this paper, the fabrication of a Cs0.2FA0.8PbI3−xBrx perovskite absorber layer using the sequential deposition route is reported. The concentration of bromine was varied in the range 0 ≤ x ≤ 1 and optical, structural, and morphological properties of the films were studied. As the concentration was increased, the perovskite showed better crystallinity and the presence of large grains with high surface roughness, indicating the formation of the CsPbBr3 phase. Optically, the perovskite films exhibited higher absorbance in the ultraviolet (UV) range between 300 and 500 nm, hence up to x = 0.3 they can be profitably employed as a wide bandgap photon absorber layer in solar cell applications.

Simulating the Performance of a Formamidinium Based Mixed Cation Lead Halide Perovskite Solar Cell

With the aim of decreasing the number of experiments to obtain a perovskite solar cell (PSC) with maximum theoretical efficiency, in this paper, PSC performance was studied using the program solar cell capacitance simulator (SCAPS-1D). The PSC with the architecture ITO/TiO2/perovskite/spiro-MeOTAD/Au was investigated, while the selected perovskite was mixed cation Rb0.05Cs0.1FA0.85PbI3. The analysis was based on an experimentally prepared solar cell with a power conversion efficiency of ~7%. The PSC performance, verified by short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (PCE), was studied by optimization of the simulation parameters responsible for improvement of the cell operation. The optimized parameters were absorber layer thickness, doping, defect concentration and the influence of the resistivity (the net effect of ohmic loss, Rs and the leakage current loss represented by the resistivity, Rshunt). The results of SCAPS-1D simulations estimated the theoretical power conversion efficiency of 15% for our material. We have showed that the main contribution to improvement of solar cell efficiency comes with lowering ohmic resistivity of the cell as well as doping and defect concentration, because their concentration is proportional to recombination rate.