Defects and doping engineering towards high performance lead-free or lead-less perovskite solar cells

Regulating charge carrier extraction and transport with dual-interface modification for efficient perovskite solar cells

“…Metal halide perovskites have been receiving tremendous attention both from academia and industry for the photovoltaic application owing to their inherent excellent physical and chemical properties such as high absorption coefficients, large carrier mobility, tunable bandgaps, and long carrier diffusion length. [1][2][3][4][5][6] The power conversion efficiency (PCE) of corresponding perovskite solar cells (PSCs) has surged from the original 3.8% 7 to the current certified 25.7% 8 over the past decade, which presents great potential to rival that of the commercialized silicon solar cells. However, the record PCE of these devices is still far below the limit of the theoretical prediction for single junction solar cells, where the relatively low fill factor (FF) is one of the most important reasons.…”

Multifunctional Molecule Assists Passivate Method to Simultaneously Improve the Efficiency and Stability of Perovskite Solar Cells

“…Perovskite devices are easily invaded by water or oxygen, mainly due to the I − vacancies where redox reaction can easily occur. For under‐coordinated Pb 2+ ions on perovskite surface and GBs, they will cause non‐radiation recombination, hinder transmission of electrons and holes, reduce the lifetime of carriers and degrade performances of devices [12–14] . In this work, a multifunctional small organic molecule 2‐chlorothiazole‐4‐carboxylic acid (SN) is reported to create polycrystal perovskite films with low inherent defect density and enhance the stability and PCE of PSCs.…”

“…For under-coordinated Pb 2+ ions on perovskite surface and GBs, they will cause non-radiation recombination, hinder transmission of electrons and holes, reduce the lifetime of carriers and degrade performances of devices. [12][13][14] In this work, a multifunctional small organic molecule 2-chlorothiazole-4carboxylic acid (SN) is reported to create polycrystal perovskite films with low inherent defect density and enhance the stability and PCE of PSCs. Compared with other organic molecules, thiazole ring contains the S and N donor atoms, which are more suitable for reacting with underco-ordinated Pb 2+ ions and I À vacancies via the lone pair electrons, facilitating the formation of stronger covalent bonds at the interfaces, and thereby passivating inherent defects.…”

Dendrimer Modification Strategy Based on the Understanding of the Photovoltaic Mechanism of a Perovskite Device under Full Sun and Indoor Light

“…It is widely accepted that the defects inevitably exist in polycrystalline perovskite thin films, , such as component ion vacancy defects, intrinsic defects V Pb (Pb i vacancy), and Pb–I antisite defects due to the low-temperature solution process for preparing perovskite thin films . These defects can be optimized in terms of improving the quality of the perovskite films, improving the electrical properties of the charge transport layer, and building efficient hybrid block copolymer/perovskite solar cells. − Moreover, these charged defects can capture carriers to form a nonradiative recombination center in the surface of the perovskite thin film and can be passivated by ligand binding and ionic bonding, such as the Lewis acid, fullerene derivatives, ionic liquid, and conjugated polymer. − Compared with small molecule materials, macromolecule materials with more functional groups have more stable and reliable interactions with perovskite crystals. , For instance, polymers usually contain Lewis acids or bases with N, O, or S atoms of lone-pair electrons, such as carbonyl, carboxyl, thiol, and amino groups, which are significant for vacancy passivation on the perovskite GBs/surface. − However, polymers generally have a higher resistivity (10 11 to 10 16 Ω cm) than perovskite materials (10 7 to 10 10 Ω cm); as a result, the amount of polymer additive is negligible to balance the passivation effect and the introduced parasitic R s . Therefore, macromolecule materials with small molecular weight but a large number of passivation groups are ideal passivation materials.…”