Abstract Hole transport layer‐free, carbon‐based, all‐inorganic CsPbI 3 perovskite solar cells (PSCs) have exhibited great potential in photovoltaic applications owing to their low cost and excellent thermal stability. However, the low power conversion efficiency (PCE) hampers its development, mainly due to the existence of defects inside the CsPbI 3 film or at TiO 2 electron transport layer/CsPbI 3 interface. Herein, these issues were addressed through a facile TiO 2 post‐treatment strategy using 1‐butyl‐3‐methylimidazole hexafluorophosphate (BMIMPF 6 ) ionic liquid. First, BMIMPF 6 can passivate TiO 2 /CsPbI 3 interface defects by forming strong bond between the electron‐rich N atoms and uncoordinated ions. Second, BMIMPF 6 ‐modified TiO 2 shows reduced hydrophilicity, inducing decreased heterogeneous nucleation and is favorable for obtaining high‐quality CsPbI 3 film. Thirdly, the non‐volatile BMIMPF 6 can diffuse to the perovskite film surface during annealing, further passivating defects located at perovskite grain boundaries and surface. Based on this one‐step ionic liquid interface‐to‐bulk modification, the modified device achieves a champion PCE of 15.09%, which is 14% higher than the control device (13.27%). In addition, the modified device also shows enhanced long‐term stability, which remains 96% of initial PCE after 30 days storage in dry air. The work demonstrates the superiority of multifunctional ionic liquid applied to all‐inorganic carbon‐based PSCs, providing a guidance for its commercialization.
Abstract In order to improve the thermal stability of perovskite solar cells (PSCs) and reduce production costs, hole transport layer (HTL)‐free carbon‐based CsPbI 3 PSCs (C‐PSCs) have attracted the attention of researchers. However, the power conversion efficiency (PCE) of HTL‐free CsPbI 3 C‐PSCs is still lower than that of PSCs with HTL/ metal electrodes. This is because the direct contact between the carbon electrode and the perovskite layer has a higher requirement on the crystal quality of perovskite layer and matched energy level at perovskite/carbon interface. Herein, the acyl chloride group and its derivative trichloroacetyl chloride are used to passivate CsPbI 3 C‐PSCs for the first time. The results show that the carbonyl group of trichloroacetyl chloride can effectively passivate the uncoordinated Pb 2+ ions in perovskite. At the same time, leaving group Cl − ions can increase the grain size of perovskite and improve the crystallization quality of perovskite layer. In addition, the trichloroacetyl chloride tends to generate cesium chloride acetate, which acts as an electron blocking layer, reduces charge recombination, promotes gradient energy level arrangement, and effectively improves the separation and extraction ability of carriers. The PCE of CsPbI 3 HTL‐free C‐PSCs is successfully increased from 13.40% to 14.82%.
Inorganic CsPbI2Br carbon-based perovskite solar cells (C-PSCs) are considered as an alternative promising contender in the field of photovoltaics, attributed to their remarkable thermal stability and cost-effectiveness. However, the defects located at the electron transporting layer (ETL)/perovskite interface (i.e., buried interface) and unsatisfactory crystallinity of CsPbI2Br films hinder the progress in enhancing the power conversion efficiency (PCE). Herein, we put forward facile acetate-assisted buried interface engineering to passivate TiO2/perovskite interface defects along with regulate the crystallization process of CsPbI2Br. Multifunctional small molecule interface modifier zinc acetate (Zn(Ac)2) is introduced into the surface of TiO2 ETL, which can passivate the oxygen vacancy defects of TiO2 and optimize the energy level alignment at the TiO2/CsPbI2Br interface. Meanwhile, part of Ac– may be dissolved in the CsPbI2Br precursor to retard its nucleation process, leading to enhanced crystallinity with a larger grain size of the CsPbI2Br film. As a result, reduced interface defects and bulk defects as well as enhanced electron extraction are achieved, which substantially enhance the PCE of CsPbI2Br C-PSCs from 12.54% to 14.20%, among the highest values of this type of device. Besides, thermal and long-term storage stabilities of the optimized devices are improved.
Hole-transporting layer (HTL)-free CsPbI3 carbon-based perovskite solar cells (C-PSCs) are regarded as a promising photovoltaic candidate due to their low cost and enhanced device stability. However, the imperfect perovskite/carbon interface, including surface defects of CsPbI3 films, unmatched energy level alignment, etc., leads to a low power conversion efficiency (PCE) and thus hampers its further development for commercialization. Herein, a multifunctional interface modifier octylammonium iodide (OAI) is introduced into the CsPbI3/carbon interface, which can not only reduce the amount of residual PbI2 at grain boundaries by converting PbI2 to the (OA)2PbI4 two-dimensional (2D) phase but also passivate defects located at the surface and grain boundaries of CsPbI3 films. Consequently, greatly reduced defect density of CsPbI3 films as well as matched energy level alignment of the CsPbI3/carbon interface are achieved, which significantly boost the PCE of CsPbI3 C-PSCs from 12.97 to 14.64%. Moreover, due to the reduced amount of PbI2 at grain boundaries and the hydrophobic property of long-chain alkyl in OAI, the unencapsulated CsPbI3 C-PSCs demonstrate excellent long-term ambient stability, which can retain 91% of its initial PCE after 30 days of storage in air.
With the continuous advancement of economic globalization, corporate mergers and acquisitions have become an important way for companies to enhance their competitiveness and accelerate their transformation and development.In order to speed up the merger process, companies often carry out mergers and acquisitions at a premium, accompanied by the generation of huge amounts of goodwill.On the one hand, a huge amount of goodwill indicates the excellent profitability of the acquired party in the future accounting period; on the other hand, when the acquired company does not realize the expected income or fails to meet the performance promise, the acquired company will impair the accounting for a huge amount of goodwill, which has a negative impact on the company's operations.Therefore, this paper attempts to provide suggestions for the confirmation and measurement of the goodwill of crossindustry enterprise mergers and acquisitions.
Abstract Formamidinium lead iodide (FAPbI 3 ) perovskite has lately surfaced as the preferred contender for highly proficient and robust perovskite solar cells (PSCs), owing to its favorable bandgap and superior thermal stability. Nevertheless, volatilization and migration of iodide ions (I − ) result in non‐radiating recombination centers, and the presence of large formamidine (FA) cations tends to cause lattice strain, thereby reducing the power conversion efficiency (PCE) and stability of PSCs. To solve these problems, the lead formate (PbFa) is added into the perovskite solution, which effectively mitigates the halogen vacancy and provides tensile strain outside the perovskite lattice, thereby enhancing its properties. The strong coordination between the C═O of HCOO − and Pb–I backbones effectively immobilizes anions, significantly increases the energy barrier for anion vacancy formation and migration, and reduces the risk of lead ion (Pb 2+ ) leakage, thereby improving the operation and environmental safety of the device. Consequently, the champion PCE of devices with Ag electrodes can be increased from 22.15% to 24.32%. The unencapsulated PSCs can still maintain 90% of the original PCE even be stored in an N 2 atmosphere for 1440 h. Moreover, the target devices have significantly improved performance in terms of light exposure, heat, or humidity.
Planar n–i–p perovskite solar cells (PSCs) based on a SnO 2 electron transport layer dominate the certified high‐efficiency devices. However, the defects located at the SnO 2 /perovskite interface (i.e., buried interface) or inside the perovskite films impede the further improvement of power conversion efficiency (PCE). Herein, nickel acetate (NiAc 2 ) is introduced on buried interface as a bidirectional modifier to improve electron extraction of SnO 2 and the crystal growth of perovskite for the first time. First, NiAc 2 is chemically anchored on SnO 2 to passivate oxygen vacancies, increase conductivity, and optimize the energy level alignment of the buried interface. Second, the porous morphology of PbI 2 film deposited on NiAc 2 ‐modified SnO 2 endows more sufficient permeation and reaction of organic amine salts (formamidinium iodide [FAI] and methylammonium iodide [MAI]), forming high‐quality perovskite film with reduced PbI 2 residues. Meanwhile, NiI 2 and MAAc/FAAc may be produced via in situ reaction between NiAc 2 and organic amine salts, which serve as interface modifier and crystallization regulator to further reduce defects located at the buried interface or inside the perovskite film, respectively. Consequently, an improved PCE of 23.02% for SnO 2 ‐based PSCs with an ultrahigh open‐circuit voltage of 1.17 V is obtained. In addition, long‐term storage and light stability of the optimized PSCs are improved.
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