Buried Interface Optimization for Flexible Perovskite Solar Cells with High Efficiency and Mechanical Stability.

An efficient guanidinium isothiocyanate additive for improving the photovoltaic performances and thermal stability of perovskite solar cells

PhDMADBr assisted additive or interface engineering for efficient and stable perovskite solar cells fabricated in ambient air

Abstractengineering has emerged as a promising approach to improve the stability and power conversion efficiency of perovskite solar cells (PSCs) by regulating the crystallization or defects. Conventional methods typically focus on a single functional group, leading to a deficiency in simultaneously addressing the above mentioned two aspects. Here, an innovative approach using (methylsulfonyl)phenyl)prop‐2‐en‐1‐amine hydroiodide (MSPPAI) is presented to concurrently and effectively modulate perovskite crystallization and defect passivation. The unique structure of MSPPAI, combining a rigid conjugated structure with multisite anchoring groups (─NH2 and ─SO2─), enables precise regulation through strong interaction with perovskite components. This interaction promotes the preferred (100) orientation of perovskite crystals, enhances the grain size, and thus improves the film quality. Meanwhile, the conjugated structure and approximate coplanarity further facilitate ordered crystallization and directional growth. Furthermore, by preventing volatile loss and coordinating with residual Pb2+, MSPPAI could effectively stabilize grain boundaries and surfaces to reduce defects and prevent degradation. Utilizing these mechanisms, the corresponding MSPPAI based devices achieves an efficiency of 25.54% and exhibits excellent stability that maintains 93% of its initial efficiency even after 1600 h under humid conditions. This molecular design strategy presents a novel approach for improving the efficiency and stability of PSCs.

Although the research on perovskite solar cells (PSCs) has achieved rapid progress, its efficiency and stability still need to be further improved to meet the industrial requirements. The defects located inside the cells, on the surfaces, interfaces, or grain boundaries, will primarily affect carrier transportation through the formation of nonradiative recombination centers and hinder the further enhancement of the power conversion efficiency (PCE). Herein, a straightforward and simple defect passivation method is developed to increase the PCE and stability of PSCs. In the device, the N‐type semiconductor AgBiS2 is introduced by thermal evaporation as a modified layer between the perovskite films and electron transport layer, which can improve the charge transport characteristic and bandgap optimization of PSCs. Simultaneously, dimethyl sulfoxide (DMSO) solvent mixed polyethylene glycol (PEG) is used for solvent annealing treatment, which can further improve the quality of perovskite film and reduce the trap density by increasing grain size and enhancing the crystallinity. As a result, the PSCs with dual‐interfacial modification exhibit a remarkable improvement in PCE from 18.58% to 21.19% with exceptional long‐term and moisture stability. This work provides an innovative insight for fabricating the stable and efficient PSCs toward the industrialization.

A compromise between high power conversion efficiency and long-term stability of hybrid organic-inorganic metal halide perovskite solar cells is necessary for their outdoor photovoltaic application and commercialization. Herein, a method to improve the stability of perovskite solar cells under water and moisture exposure consisting of the encapsulation of the cell with an ultrathin plasma polymer is reported. The deposition of the polymer is carried out at room temperature by the remote plasma vacuum deposition of adamantane powder. This encapsulation method does not affect the photovoltaic performance of the tested devices and is virtually compatible with any device configuration independent of the chemical composition. After 30 days under ambient conditions with a relative humidity (RH) in the range of 35-60%, the absorbance of encapsulated perovskite films remains practically unaltered. The deterioration in the photovoltaic performance of the corresponding encapsulated devices also becomes significantly delayed with respect to devices without encapsulation when vented continuously with very humid air (RH > 85%). More impressively, when encapsulated solar devices were immersed in liquid water, the photovoltaic performance was not affected at least within the first 60 s. In fact, it has been possible to measure the power conversion efficiency of encapsulated devices under operation in water. The proposed method opens up a new promising strategy to develop stable photovoltaic and photocatalytic perovskite devices.

Carrier Dynamics Engineering for High-Performance Electron-Transport-Layer-free Perovskite Photovoltaics

Organic-inorganic perovskites have emerged as an interesting class of materials that have excellent photovoltaic properties for application to solar cells. The power conversion efficiency of perovskite solar cells over 20% has already been realized through systematic optimization of materials and fabrication processes. However, the long-term stability of perovskite solar cells still need to be improved for practical applications. In this study, we introduced a multifunctional benzoquinone (BQ) additive into a precursor solution containing methylammonium iodide (MAI) and lead iodide (PbI2) used for spin-coating of perovskite films. Resulting spin-coated perovskite films containing BQ had the improved perovskite morphology and crystal quality because of intermolecular interaction between MAI and BQ slowing the rate of perovskite crystal formation. Therefore, we obtained the greatly enhanced power conversion efficiency from 10.7% to 15.6%. The reduced charge recombination loss by electron transfer from perovskite to BQ is another source of the improved efficiency. In addition to the efficiency enhancement, the BQ addition led to the extended lifetime about twenty-six times. The lifetime, at which efficiency reduces to 80% of the initial under the one-sun condition (100 mW/cm2 and AM1.5G), reached about 4000 h, one of the longest lifetimes ever reported in perovskite solar cells. The extended lifetime can be explained by the reduced formation of carrier traps originating from metallic lead during solar irradiation as the results of thermally stimulate current measurements. We believe that the present findings offer insight to help obtain efficient, stable organic-inorganic perovskite solar cells for future applications.

Simultaneous bottom-up double-layer synergistic engineering by multifunctional natural molecules for efficient and stable SnO2-based planar perovskite solar cells

Dual interfacial engineering to improve ultraviolet and near-infrared light harvesting for efficient and stable perovskite solar cells

Influence of anti-solvents on CH3NH3PbI3 films surface morphology for fabricating efficient and stable inverted planar perovskite solar cells

Organohalide lead perovskites (PVKs) are among the most promising materials for creating high-efficiency and low-cost photovoltaic devices. However, challenges such as high trap densities, low crystallinity, and moisture sensitivity in perovskite films hinder the performance and stability of perovskite solar cells (PSCs). In this work, we address these limitations by incorporating a green, environmentally friendly nanocomposite multi-walled carbon nanotube/zinc oxalate (MWCNT/Zn(COO)₂) into the electron transport layer (ETL) to enhance the performance, stability, and cost-effectiveness of PSCs. The novel ETL, comprising mesoporous TiO₂ (mp-TiO₂) combined with the MWCNT/Zn(COO)₂ layer, demonstrated superior charge extraction and reduced charge recombination at the ETL/perovskite interface, leading to significant performance improvements. Furthermore, the PSCs demonstrated remarkable stability, retaining over 70% of their initial power conversion efficiency (PCE) after 70 days of storage in ambient conditions without encapsulation, a substantial improvement over conventional mp-TiO₂-based devices. Additionally, replacing expensive metals, such as gold (Au), with cost-effective carbon paste further reduces production costs, enhancing the economic viability of the devices. This work highlights the potential of the MWCNT/Zn(COO)₂ nanocomposite to enhance the efficiency and stability of PSCs, paving the way for greener and more cost-effective photovoltaic technologies.

The power conversion efficiency of perovskite solar cells continues to increase. However, defects in perovskite materials are detrimental to their carrier dynamics and structural stability, ultimately limiting the photovoltaic characteristics and stability of perovskite solar cells. Herein, we report that 6H polytype perovskite effectively engineers defects at the interface with cubic polytype FAPbI3, which facilitates radiative recombination and improves the stability of the polycrystalline film. We particularly show the detrimental effects of shallow-level defect that originates from the formation of the most dominant iodide vacancy (VI+) in FAPbI3. Furthermore, additional surface passivation on top of the hetero-polytypic perovskite film results in an ultra-long carrier lifetime exceeding 18 μs, affords power conversion efficiencies of 24.13% for perovskite solar cells, 21.92% (certified power conversion efficiency: 21.44%) for a module, and long-term stability. The hetero-polytypic perovskite configuration may be considered as close to the ideal polycrystalline structure in terms of charge carrier dynamics and stability.

Three ionic surfactants, didodecyldimethylammonium bromide (DDABr), sodium lauryl ether sulfate (NaLES) and sodium lauryl sulfate (NaLS), with different dipole moment values: 0.907, 17 and 212 Debye, respectively, have been used as anti-solvent additives to remove the moisture from perovskite precursor solutions. The three additives impact in different ways on the crystallinity, wettability and morphology of perovskite thin films, as well as on the stability and efficiency of air-processed perovskite solar cells (PSCs). The hydrophobic groups of the additives at the surface of perovskite thin films help to increase the stability of PSCs, especially DDABr of the lowest dipole moment. On the other hand, NaLES, of the highest dipole moment, is the most efficient to extract moisture from the perovskite precursor coatings, increasing the average power conversion efficiency (PCE) of NaLES-based PSCs from 16.16 ± 0.94% to 17.21 ± 0.32% in comparison with that of the reference. Furthermore, the synergy between NaLES and the perovskite precursor additive, KI, achieves the best photovoltaic performance of the PSCs, leading to an average PCE of 17.42% and the best PCE of 18.75%. It is concluded that ionic surfactants of different dipole moments are good candidates as anti-solvent additives to improve the efficiency and stability of air-processed PSCs.

Post-treatment by an ionic tetrabutylammonium hexafluorophosphate for improved efficiency and stability of perovskite solar cells

Multifunctional 2D perovskite capping layer using cyclohexylmethylammonium bromide for highly efficient and stable perovskite solar cells