Search

Perovskite solar cells with mesoporous TiO2electron transport layers have previously reached >22 % efficiency at the laboratory scale (<1 cm2), however, these layers are fabricated using spin‐coating, which is not conducive to large‐scale or high throughput fabrication. This report describes the inkjet printing of open‐pore mesoporous TiO2thin films, perovskite thin films, and the fabrication of highly efficient perovskite solar cells using these films. Ink formulation and characterization studies, inkjet deposition optimization trials, film characterization, and comparison to spin‐coated layers are described. The printed TiO2films exhibited an open‐pore morphology and homogeneous surface coverage in films ranging from 1 mm2to >10 cm2. Perovskite solar cells with printed and pristine (un‐doped) inkjet‐printed TiO2layers yielded efficiencies of 18.29 %, which were found to outperform cells made with spin‐coated and pristine TiO2layers (16.91 %). When a quadruple‐cation perovskite absorber containing Cs, formamidinium, methylammonium, and guanidinium was deposited by inkjet‐printing onto the inkjet‐printed TiO2layer, nearly 12 % average efficiency was reached, with the champion cell reaching 14.11 %. This absorber exhibited higher efficiency and stability than did inkjet‐printed MAPbI3films deposited on the inkjet‐printed TiO2film. This report describes the inkjet printing of open‐pore mesoporous TiO2thin films, perovskite thin films, and the fabrication of highly efficient perovskite solar cells using these films. Devices incorporating an inkjt‐printed TiO2layer outperformed devices with spin‐coated devices.

Nanoscale CH3NH3PbI3perovskite sensitizers are grown by delivering each precursor successively onto the surface of mesoporous (meso) TiO2electrodes. Using Pb(NO3)2ions as a lead(II) source and CH3NH3I (MAI) for methylammonium and iodide sources, repetitive cycles of the two dipping steps are successful in growing few nanometer‐sized MAPbI3gradually on the TiO2surface inside the meso‐TiO2film. However, some aggregates are observed on the top surface of the meso‐TiO2film due to slight dissolution of PbI2and its accumulation/reaction with MAI at the top surface of the meso‐TiO2film. To solve this inhomogeneity of the deposition, a nondestructive multiple deposition route for nanoscale MAPbI3is suggested as a successive precursor layer adsorption and reaction (SPLAR) process where, from the second cycle of deposition, PbI2is delivered with the help of an ionic liquid compound dissolved in dichloromethane. With this new Pb precursor in less‐polar solvents, nanoscale MAPbI3sensitizers are grown without dissolution of preformed perovskites or formation of some aggregates at the top surface. After the third cycle of SPLAR deposition, about 7.0 nm–sized MAPbI3sensitizers are prepared and display enhanced photovoltaic performance (7.18 ± 0.31%) compared with devices obtained from only one cycle (5.74 ± 0.30%). New successive precursor layer adsorption and reaction (SPLAR) is successfully applied to grow nanoscale MAPbI3perovskite photosensitizers by way of step by step on the surface of mesoporous TiO2film homogeneously, whereas old successive ionic layer adsorption and reaction (SILAR) is turned out to produce both nanoscale dots inside the film and bigger aggregates at the top surface.

Inkjet‐Printed Mesoporous TiO2and Perovskite Layers for High Efficiency Perovskite Solar Cells: Inkjet‐Printing of “open‐pore” TiO2thin films and Cs0.10Gua0.05FA0.83MA0.17PbI2.63Br0.37perovskite is studied, with optimized inkjet‐printed TiO2film structures eventually yielding higher efficiencies when incorporated in photovoltaic devices than spin‐coated TiO2films. A quadruple cation perovskite absorber layer is then inkjet‐printed on the printed TiO2films and devices optimized to yield champion device efficiencies >14 % PCE. More details can be found in the Full Paper by Aron J. Huckaba et al. on page 317 in Issue 2, 2019(10.1002/ente.201800905).