The ionic nature endows halide perovskites with intrinsic interfacial defects in the formed polycrystalline films, thus imposing the challenge of synchronously passivating these defects with low formation energies that directly account for the unsatisfied performance of perovskite solar cells (PSCs). By virtue of the theoretically proven capability of a three to four times enhancement of the formation energy of each defect of Pb‐I antisite (PbI) and iodine vacancy (VI), a new passivation molecule of 1,10‐phenanthrolin‐5‐amine (PAA) is intentionally explored to synchronously passivate the dual defects. The pronounced passivation effect is experimentally verified by the sharp enhancement of the open‐circuit voltage in ternary PSCs from the original 1.118 up to 1.207 V, as well as the construction of PAA‐modified formamidinium lead iodide PSCs with a champion efficiency up to 24.06%, thus providing a universal alternative of addressing interfacial charge carrier dynamics and operational stability of PSCs that are bothered by the multiple interfacial defects.
It is facing a tremendous challenge to develop the desirable hybrids for photocatalytic H2 generation by integrating the advantages of a single semiconductor. Herein, an all‐sulfide ZnIn2S4/CdS/PdS heterojunction is constructed for the first time, where CdS and PdS nanoparticles anchor in the spaces of ZnIn2S4 micro‐flowers due to the confinement effects. The morphology engineering can guarantee rapid charge transfer owing to the short carrier migration distances and the luxuriant reactive sites provided by ZnIn2S4. The S‐scheme mechanism between ZnIn2S4 and CdS assisted by PdS cocatalyst is testified by in situ irradiated X‐ray photoelectron spectroscopy and electron paramagnetic resonance (EPR), where the electrons and holes move in reverse driven by work function difference and built‐in electric field at the interfaces. The optimal ZnIn2S4/CdS/PdS performs a glaring photocatalytic activity of 191.9 µmol h−1 (10 mg of catalyst), and the largest AQE (apparent quantum efficiency) can reach a high value of 26.26%. This work may afford progressive tactics to design multifunctional photocatalysts.
Electron transport layers (ETLs) with pronounced electron conducting capability are essential for high performance planar perovskite photovoltaics, with the great challenge being that the most widely used metal oxide ETLs unfortunately have intrinsically low carrier mobility. Herein is demonstrated that by simply addressing the carrier loss at particle boundaries of TiO2 ETLs, through embedding in ETL p–n heterointerfaces, the electron mobility of the ETLs can be boosted by three orders of magnitude. Such embedding is encouragingly favorable for both inhibiting the formation of rutile phase TiO2 in ETL, and initiating the growth of high‐quality perovskite films with less defect states. By virtue of these merits, creation of formamidinium lead iodide perovskite solar cells (PSCs) with a champion efficiency of 25.05% is achieved, setting a new benchmark for planar PSCs employing TiO2 ETLs. Unencapsulated PSCs deliver much‐improved environmental stability, i.e., more than 80% of their initial efficiency after 9000 h of air storage under RH of 40%, and over 90% of their initial efficiency at maximum power point under continuous illumination for 500 h. Further work exploring other p‐type nanocrystals for embedding warrants the proposed strategy as a universal alternative for addressing the low‐carrier mobility of metal oxide based ETLs.
To effectively restrain the charge recombination of bulk CdS, which dominantly limits the photocatalytic activity, ultrathin CdS−NiFeS two-dimensional (2D)−2D heterojunctions are well designed with the creation of tight interfaces, where NiFeS nanosheets derived from layered double hydroxides possess tunable work functions and hydrogen evolution overpotentials. The optimized CdS−2% NiFe 0.1 S photocatalyst presents an excellent hydrogen generation activity of 626.7 μmol/h (10 mg catalysts, equivalent to 62.67 mmol/g/h), which is fairly high among noble-metal-free CdS-based catalysts. The greatly enhanced catalytic performance can be ascribed to the following synergetic effects. This ultrathin 2D−2D heterostructure formed between CdS and NiFeS establishes sufficient contact interfaces, shortens the charge transport distance, and efficiently accelerates the electron transfer from CdS to NiFeS, which possesses a large work function. Moreover, the bimetallic NiFeS cocatalyst evidently decreases the reaction barrier, provides abundant active sites, and then facilitates H 2 generation. This research may offer new inspirations to develop 2D nanomaterials for outstanding photocatalytic performance.
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