Bionic Levodopa-Modified TiO₂ for Preparation of Perovskite Solar Cells with Efficiency over 23%

Abstract

TiO2 is one of the most common electron transport layer materials, but its poor conductivity, charge extraction, and photostability pose great challenges to the efficiency and stability of perovskite solar cells. Herein, a levodopa molecule was chlorinated to form LDA-Cl in a TiO2 precursor solution for the modification of TiO2 via the phenolic hydroxyl group of levodopa. Uncoordinated lead ions and halogen vacancies of a perovskite can be passivated by carboxyl and chloride ions of LDA-Cl. The as-prepared TiO2/LDA-Cl film exhibits higher conductivity and flatness after annealing and could be well suited for the preparation of large-grain perovskites. The appropriate energy level position and excellent electrical conductivity of the as-obtained TiO2/LDA-Cl can accelerate the charge extraction and inhibit the recombination of electron–hole pairs at the interface between the perovskite and TiO2. The nonradiative recombination of the LDA-Cl-based perovskite solar cell is suppressed, and the defect density is reduced from 5.513 × 1016 to 5.093 × 1016 cm–3 due to the passivation effect of carboxyl and chlorine of LDA-Cl. The photoelectric conversion efficiency of the as-prepared perovskite solar cell increased to 23.28 from 21.91%, and the PCE of the device remained at 90% of the initial value after 4000 h (T = 25 °C, RH = 25%).

Dopamine Sulfonate Ligand-Assisted TiO2 Deposition Enabling Highly Efficient and Stable Perovskite Solar Cells

“…(3) The terminal sulfonate of DS are widely accepted as effective passivators for perovskite, − which can form a bridge-linked structure at the buried interface to repair traps of the perovskite films. (4) PSCs that utilize TiO 2 as ETLs often exhibit poor operational stability, mainly attributed to the abundance of Ti 3+ -oxygen vacancy (Vo) within the TiO 2 material . When exposed to UV (ultraviolet) irradiation, these Ti 3+ generate electrons and Ti 4+ ions, acting as deep-level defects, which accelerate nonradiative recombination of electron–hole pairs and can also induce degradation of the perovskite components .…”

“…(4) PSCs that utilize TiO 2 as ETLs often exhibit poor operational stability, mainly attributed to the abundance of Ti 3+ -oxygen vacancy (Vo) within the TiO 2 material. 27 When exposed to UV (ultraviolet) irradiation, these Ti 3+ generate electrons and Ti 4+ ions, acting as deep-level defects, which accelerate nonradiative recombination of electron−hole pairs and can also induce degradation of the perovskite components. 28 By incorporating DS featured with oxygen-containing groups that can interact with Ti 3+ , it becomes feasible to suppress oxidation reactions and enhance the UV light resistance of the device.…”

Simulation and Verification of the Direct Current Electric Field on Fabricating High Porosity f-MWCNTs Thin Films by Electrophoretic Deposition Technique

“…Among them, perovskite PVs emerge as a potential candidates due to their outstanding solar-to-power conversion efficiency . Many different groups of materials have been studied and applied to the hole transport layer (HTL), − electron transport layer (ETL), − and perovskite layer − to enhance the efficiency and stability of perovskite PVs. Carbon nanotubes (CNTs) have attracted worldwide attention to solve this problem due to their unique structure, outstanding mechanical strength and thermal conductivity, and versatile electronic properties. − In addition, they possess the limitless potential for decorated additional functions through chemical modification. − Many studies show that the presence of CNTs in perovskite PVs can passivate the defect sites in halide perovskites, preventing charge recombination in the perovskite layer. − Incorporating CNTs into PVs as a notable strategy in improving the device’s solar energy harvester capabilities, efficiency, stability, and low cost helps bring perovskite PVs and nanocarbon-based PVs closer to widespread commercialization. − …”

Reduction-Active Antisolvent: A Universal and Innovative Strategy of Further Ameliorating Additive Optimization for High Efficiency Perovskite Solar Cells

“…Organic–inorganic hybrid halide perovskite solar cells (PSCs) have attracted significant attention in recent years owing to their unique photoelectric properties, such as high absorption coefficient, efficient charge transport, long carrier diffusion, and tunable direct bandgap. − The certified power conversion efficiency (PCE) of related devices has advanced to 25.8% and is still being pushed toward the Shockley–Queisser (SQ) efficiency limit. − Although the photovoltaic performance of PSCs has developed tremendously and is now competitive with that of other commercially available solar cells, intrinsic instability remains the main obstacle that seriously limits the future applications of PSCs. Because of the soft structure and inherent ionic nature of [PbI 6 ] 4– octahedral frameworks, perovskite films are sensitive to the actual operating process and the surrounding environment, such as heat, oxygen, deformation, and humidity. − This can damage the crystal structure of the perovskite and generate undesired defects that function detrimentally as nonradiative recombination sites.…”