Reduced Charge Recombination Research Articles

Photodeposition Synthesis of CdS@Ni2P Composites for Efficacious Photocatalytic Hydrogen Evolution

Noble-metal-free semiconductor composites are very valuable for efficient water splitting driven by visible light. In this paper, CdS@Ni2P was successfully prepared by a simple hydrothermal method followed by in situ photodeposition. The results showed that the best photocatalytic hydrogen production rate of the composite is 287 μmol h–1, which is about 98.3 times that of pure CdS. The high activity of the material may be attributed to the intimate interface between the Ni2P cocatalyst and CdS nanorods for accelerating the separation and transport of photoelectrons. Further UV and PL tests found that Ni2P significantly extends the lifetime of photogenerated charge carriers and reduces charge recombination rates, resulting in improved photocatalytic H2 production performance. The potential mechanism of photocatalytic enhancement of CdS@Ni2P composite samples was proposed based on the experimental results and DFT calculation, which could lead to a neoteric approach for the efficient preparation of other photocatalytic materials.

Hierarchically interconnected g-C3N4/BiVO4/ZnO array via spin coating for high photoelectrochemical performance

An interconnected g-C3N4/BiVO4/ZnO array system was constructed to enhance photoelectrochemical (PEC) performance. This study confirmed that an optimally decorated ZnO layer improves PEC performance by maximizing light absorbance and reducing charge recombination. Moreover, the layer also plays a significant role in passivating the underneath g-C3N4/BiVO4 components to increase the stability of the photoanodes and charge carrier concentration. With the Z-scheme g-C3N4/BiVO4 heterojunction structure, electrons can be easily transferred while blocking holes to minimize charge recombination. The oxygen vacancies in the ZnO layer are good for high PEC performance with a reduced bandgap of the g-C3N4/BiVO4/ZnO array. The formation of interconnected interfaces reduces the interface contact resistance, promotes charge transfer, and consequently improves the PEC performance. The interconnected g-C3N4/BiVO4/ZnO array is a promising candidate for overcoming the inherent negative properties of individual metal oxides for application in future solar-driven reaction systems.

Manganese phosphorous trifulfide nanosheets and nitrogen doped carbon dot composites with manganese vacancies for a greatly enhanced hydrogen evolution

As a novel chalcogenide photocatalyst, MnPS3 suffered from limited visible light absorption, high photogenerated electron-hole recombination, and low hole oxidation capability due to its high valence band (VB) potential. In this work, the novel MnPS3 nanosheets-Nitrogen-doped carbon dots (NCDs) composites were fabricated by immobilizing NCDs with terminal amine groups on Na+ intercalated MnPS3 nanosheets for a greatly enhanced photocatalytic hydrogen production activity. MnPS3 nanosheets of 400 nm with Mn2+ vacancies are produced in high yield by NaCl intercalation and subsequent exfoliation in N-methylpyrrolidone (NMP). NCDs with 5 nm are evenly loaded on the surface of MnPS3 nanosheets of 400 nm via strong chemical interactions of ammonium sulfate salts formed at the interface. The MnPS3-NCDs composites exhibit enhanced light absorption at 500–600 nm, reduced charge recombination and notably promoted photocatalytic activity in relative to neat MnPS3 nanosheets. MnPS3-NCDs composite with the NCDs content of 16.5% possessed the highest photocatalytic hydrogen evolution rate of 339.63 μmol·g−1·h−1 with good cycling stability, which is 9.17 times that of exfoliated MnPS3 nanosheets. The type-II MnPS3-NCDs heterojunction is conducive to the efficient interfacial carrier transport and the significantly improved photocatalytic hydrogen generation activity. Our work confirmed that the non-toxic MnPS3 could possess photocatalytic performance comparable to CdS, which will be promising to become an attractive visible-light driven photocatalyst in environmental purification and energy applications.

Intimately coupled gC3N4 photocatalysis and mixed culture biofilm enhanced detoxification of sulfamethoxazole: Elucidating degradation mechanism and toxicity assessment

In recent years, wide spread of antibiotic-resistant microorganisms and genes emerging globally, an eco-friendly method for efficient degradation of antibiotics from the polluted environment is essential. Intimately coupled photocatalysis and biodegradation (ICPB) using gC3N4 for enhanced degradation of sulfamethoxazole (SMX) was investigated. The gC3N4 were prepared and coated on the carbon felt. The mixed culture biofilm was developed on the surface as a biocarrier. The photocatalytic degradation showed 74%, and ICPB exhibited 95% SMX degradation efficiency. ICPB showed superior visible light adsorption, photocatalytic activity, and reduced charge recombination. The electron paramagnetic resonance spectrum confirms that the generation of •OH and O2• radicals actively participated in the degradation of SMX into biodegradable intermediated compounds, and then, the bacterial communities present in the biofilm mineralized the biodegradable compound into carbon dioxide and water. Moreover, the addition of NO3−, PO4−, and Cl− significantly enhanced the degradation efficiency by trapping the surface electron. Stability experiments confirmed that gC3N4 biohybrid can maintain 85% SMX degradation efficiency after 5 consecutive recycling. Extracellular polymeric substances characterization results show that biohybrid contains 47 mg/L, 14 mg/L, and 13 mg/L protein, carbohydrate, and humic acid, respectively, which can protect the bacterial communities from the antibiotic toxicity and reactive oxygen species. Furthermore, biotoxicity was investigated using degradation products on E.coli and results revealed 83% detoxification efficiency. Overall, this study suggested that gC3N4 photocatalyst in an ICPB can be used as a promising eco-friendly method to degrade sulfamethoxazole efficiently.

Effects of Sn and Nb Doping on the Performance of Fe2TiO5 As a Water Splitting Photocatalyst

Very recently, pseudobrookite Fe2TiO5 has been revealed as a promising photocatalyst for the oxidation half-reaction of overall water splitting. This semiconductor is inexpensive, non-toxic, possesses a relatively small band gap, and presents improved structural and photochemical features compared to other well-known photocatalysts. In this investigation, we doped the Fe2TiO5 structure with 1.0 at% tin and 1.5 at% niobium, separately, through a solvothermal method to prolong the minority carrier diffusion length and reduce charge recombination events under visible light illumination. The procedure generated single-phase Sn- and Nb-doped Fe2TiO5 nanoparticles with dimensions close to 30 nm. In both cases, optical band gap values of 2.1 eV were observed. Pristine Fe2TiO5, Sn-doped Fe2TiO5, and Nb-doped Fe2TiO5 were irradiated by a Xe lamp (λ>400 nm), producing 59.2, 297.6 and 344.0 mmol h-1 g-1 of O2, respectively. This result reflects the substantial improvement that doping Fe2TiO5 with Sn and Nb confers to its photocatalytic water splitting activity. In addition, photoelectrochemical measurements in a 1 M NaOH electrolyte indicated photocurrent increments from 2.4 mA cm-2 at 1.23 VRHE, for the pristine Fe2TiO5, to 36.7 and 70.7 mA cm-2 at 1.23 VRHE for Sn- and Nb-doped Fe2TiO5, respectively, accompanied by overpotential drops of 0.04 and 0.1V. Electrochemical impedance spectroscopy indicated that reductions in the resistance for the charge carrier transfer resistance at the solid/liquid interface plays an important role for the performance improvement of the doped nanomaterials. Overall, this work illustrates how structural alterations of a potential photocatalyst can improve photochemical energy conversion. The authors acknowledge support from FAPESP (Grant 2017/11986-5) and Shell and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation.

Construction of an amino-rich Ni/Ti bimetallic MOF composite with expanded light absorption and enhanced carrier separation for efficient photocatalytic H2 evolution

Metal organic framework (MOF) materials are a multi-component system integrating light harvesting and catalysis for photocatalytic hydrogen production, which is of great importance for sustainable development. In present work, Ni nanoparticles were first prepared by a chemical reduction method, and then an amino-rich Ni/Ti bimetallic MOF composite was synthesized by a one-pot method. The introduction of Ni leads to the rearrangement in electronic structure and thus to reduced charge recombination in the MOFs. The introduction of amino group as a photosensitizer expands the light absorption range. Thus, the absorption of NH2-MIL-125(Ti) after Ni modification extended from 473 to 624 nm, and the hydrogen evolution rate under visible light reached 699 μmol g−1 h−1, which is about 9 times that of parent NH2-MIL-125(Ti). Ti-MOFs show a new design potential to integrate light harvesting and catalytic components for photocatalytic hydrogen production.

A Smart Way to Prepare Solution‐Processed and Annealing‐free PCBM Electron Transporting Layer for Perovskite Solar Cells

AbstractAs a state‐of‐the‐art n‐type material, PC61BM ((6,6)‐phenyl C61 butyric‐ methylester) has been largely used as the top electron transporting layer (ETL) in inverted perovskite solar cells (PSCs). Whereas so far, there have been few reports on using pristine PC61BM as the bottom ETL in conventional (n‐i‐p‐type) PSCs, because it will be partially dissolved by the perovskite precursor solution (such as N,N‐Dimethylformamide and Dimethyl sulfoxide). In this work, the successful application of pristine PC61BM as an annealing‐free ETL is reported for conventional PSCs, by ingeniously utilizing the “saturated solution” strategy. Specifically, the perovskite precursor solution is presaturated with PC61BM before deposition, in this way, not only the underlying PC61BM layer can be “reserved”, the added PC61BM in perovskite is also able to passivate defects in perovskite grain boundaries, thus facilitating charge transporting and reducing charge recombination. Encouragingly, the PC61BM ETL can avoid high‐temperature calcination or thermal annealing, thus greatly simplifying the manufacturing processes and reducing production costs. The CH3NH3PbI3–xClx‐based champion device shows the highest efficiency of 20.85% with high reproducibility. The strategy is simple, straightforward, and cost‐effective, when compared to most of the present reported ways for depositing ETLs.

Investigation of PCBM/ZnO and C60/BCP-based electron transport layer for high-performance p-i-n perovskite solar cells

The objective of this study was to comprehensively investigate and compare PCBM/ZnO and C60/BCP-based electron transport layers (ETLs) (well recognized as representative ETLs) between perovskite and metal electrode in perovskite solar cells (PeSCs) for high-performance p-i-n structure PeSCs. Their film characteristics and their effects on solar cell performances were studied. When PCBM/ZnO was used as ETL material, the PCE of PeSCs was 19.36 %, which was higher than the PCE of 17.10 % when C60/BCP was used possibly due to more efficient charge recombination reduction and charge extraction shown in PCBM/ZnO-based devices. However, in terms of stability (air, light-soaking, and heat), C60/BCP-based devices showed higher stability than PCBM/ZnO-based devices.

From pure water to hydrogen peroxide on a novel 2,5,8-triamino-tri-s-triazine (melem)-derived photocatalyst with a high apparent quantum efficiency

Photocatalytic hydrogen peroxide (H2O2) production is a green process but remains a great challenge. Herein, a novel photocatalyst with high activity for H2O2 production, is developed based on 2,5,8-triamino-tri-s-triazine (melem) by linking it with 2, 3-naphthalene dicarboxylic anhydride (NDA). The obtained melem/NDA hybrid not only exhibited narrowed band gap and obviously enhanced visible light absorption, but also showed reduced charge recombination originated from its spatial distribution in HOMO and LUMO induced by the introduction of NDA as verified by DFT calculations. More significantly, the sufficient LUMO and HOMO positions for the optimal sample, melem/NDA0.5, ensured efficient H2O2 production from pure water via both the oxygen reduction reactions mainly through the two-step one-electron path and the water oxidation reaction through the one-step two-electron path. Consequently, melem/NDA0.5 achieves an apparent quantum efficiency of as high as 6.9 % at 420 nm. This work sheds light on developing high-performance organic photocatalysts for boosting photocatalytic H2O2 production.

Fabrication of high visible light active LaFeO3/Cl-g-C3N4/RGO heterojunction for solar assisted photo-degradation of aceclofenac

The designing of semiconductor based heterojunction has proved to be an effective strategy for developing more efficient photo-catalyst than single component photo-catalyst. Herein, we report the laboratory scale fabrication of a novel LaFeO3/Cl-g-C3N4/RGO (LCCR) heterojunction with enormous photocatalytic activity. The prepared nano-composite has been characterized using X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM). The LaFeO3/Cl-g-C3N4/RGO (LCCR) nano-heterojunction exhibits excellent photocatalytic activity due to its reduced charge recombination rate. The photocatalytic potential of LCCR was tested for the photo degradation of aceclofenac drug as model pollutant. LCCR with an optimum dosage amount 200 mgL−1 has shown highest degradation of 96.4 % within 90 min of solar light exposure. Various operational parameters such as effect of pH, photocatalyst dosage, pollutant concentration and various ions has been investigated. The photo-degradation outcomes of LCCR nano-composite have been examined in terms of reaction kinetics, active radical identification experiments, high resolution mass spectrometry (HR-MS), chemical oxygen demand (COD) and total organic carbon (TOC) analysis. The photo-degradation experiment followed the pseudo first order kinetics with high rate constant k1 = 0.0461 min−1 and results for TOC and COD analysis shows that 53.2 % of TOC was removed, whereas COD was decreased to 22.4 %. This work shows promising photo-catalyst for treating pharmaceutical effluents.

Isomerization of Asymmetric Ladder‐Type Heteroheptacene‐Based Small‐Molecule Acceptors Improving Molecular Packing: Efficient Nonfullerene Organic Solar Cells with Excellent Fill Factors

AbstractMoving one subunit of the central core to the other side in a small‐molecule acceptor (SMA) is an effective approach to achieve the goal of isomerization, which has proven viable to enhance photovoltaic performance. Herein, two isomeric SMAs of ThPy5 and ThPy6 are developed by changing the position of the thiophene unit of the dithieno[3,2‐b:2′,3′‐d]pyrrol in IDTP‐4F. The effect of altering the thiophene position on morphological characteristics, macroscopic factors, and device performance is thoroughly investigated among these three isomeric SMAs. Compared to ThPy5, IDTP‐4F and ThPy6 show planar molecular structures and better molecular orientation. Moreover, tighter π–π stacking as well as enhanced electron mobility is observed in ThPy6 relative to IDTP‐4F. PM6:ThPy6‐based organic solar cells (OSCs) achieve the maximum efficiency of 16.11%, along with an excellent fill factor (FF) of 0.789, which are among the best results for A‐D‐A‐type SMA‐based OSCs. The high FF ascribes to the improved molecular packing and charge collection/extraction efficacy and the reduced charge recombination. The structure–morphology–performance relationship drawn from this work can offer better guidance for designing the molecular structure, especially the central cores of SMAs.

Green synthesis of nickel oxide coupled copper hexacyanoferrate (NiO2–CuHCF) nanocomposites for efficient and highly stable natural sunlight-driven photocatalytic degradation of wastewater pollutants

Metal hexacyanoferrates are found to be the promising candidates utilized to degrade toxic dyes from waste water under natural sunlight irradiation. Coupling of metal hexacyanoferrate with metal oxide enhances the degradation efficacy. In present work, nickel oxide coupled copper hexacyanoferrate nanocomposites (NiO2–CuHCF) are synthesized by employing facile co-precipitation route. XRD reveals the incorporation of NiO2 with CuHCF. SEM confirms the sheet like structures of NiO2–CuHCF nanocomposite. TEM demonstrates the even distribution of elements present in the NiO2–CuHCF nanocomposite. XPS shows the active participation of constituents having different valence states. The UV–Vis (DRS) is employed to measure the optical properties. The band gap of nickel oxide coupled copper hexacyanoferrate nanocomposite (NiO2–CuHCF) decreases in comparison with pure copper hexacyanoferrate (CuHCF) from 1.23 to 1.14 eV. 97% degradation of Methyl blue (MB) is observed in just 110 min by NiO2–CuHCF nanocomposite when exposed to natural sunlight. Moreover, it also retains 92% photocatalytic efficiency over 6 cycles which shows its excellent stability and reusability. The improved photocatalytic performance of NiO2–CuHCF nanocomposite is attributed to their sheet resembling morphologies which may provide adequate active sites responsible to transport more charge carriers and also reduce charge recombination. In general, this research may open new avenue to use CuHCF with the addition of NiO2 in future as an efficient degradation agent at industrial level.

Remarkable 8.3% efficiency and extended electron lifetime towards highly stable semi-transparent iodine-free DSSCs by mitigating the in-situ triiodide generation

Achieving highly stable and efficient dye-sensitized solar cells (DSSCs) remains a major challenge for future industrial development. In the present work, a series of ionic conductors, such as ionic liquids (ILs), polysiloxane-based poly(ionic liquid)s (PILs), and their blends are employed as electrolytes in quasi-solid-state DSSCs. In particular, we study the effect of PILs ionic functionality interaction with the ILs and ethylene carbonate (EC) on the photovoltaic performance of DSSCs with and without iodine (I2). Omitting I2 from the electrolytes in fabricated DSSCs enhances both Voc and Jsc due to the reduced charge recombination and extended effective electron lifetime. We confirm through Raman spectroscopy that in I2-free DSSCs, the in-situ generated tri-iodides (I3−) ions are sufficient enough to complete the reaction mechanism. Additionally, the I2-free DSSCs exhibit enhanced transparency, encouraging our efforts towards BIPV suitable applications. When plasticized with EC, the ionic conductivities of the highly functionalized I2-free PIL-based DSSCs exceeds 10−3 S cm−1 at 30 °C, giving record PCE of 8.3% and 9.1% under standard (1 sun) and modest (0.3 sun) illumination, respectively. These devices also show excellent long-term stability, retaining about 84% of their initial efficiency after 26 months.

Bromide complimented methylammonium-free wide bandgap perovskite solar modules with high efficiency and stability

Wide bandgap metal-halide perovskites are promising photoactive materials to pair with silicon in tandem solar cells to achieve power conversion efficiency (PCE) higher than 30% at low cost. In this work, we found that massive defects are generated in wide bandgap perovskites due to the release of bromide under mild annealing (100 °C), which restrains the open-circuit voltage and thus the performance of solar cells. We report a bromide complementation strategy for wide bandgap perovskites via surface treatment with trimethylphenylammonium bromide (PTABr). As a result, significantly reduced charge recombination and elongated carrier lifetime are achieved, which improves both efficiency and stability of solar cells. A champion PCE of 17.0% for large-area (5 cm × 5 cm) modules with an active area of 10 cm2 is achieved, which is one of the best performance of perovskite solar modules based on wide bandgap perovskites. The solar cells and modules show enhanced stability under the stress of moisture, illumination and heat. Moreover, we achieve a PCE of 25.0% with four-terminal perovskite/silicon tandem solar cells. These results suggest that bromide complementation is a promising way in obtaining high efficiency and large-area perovskite/Si tandem solar cells with good stability.

Simultaneously Enhanced Efficiency and Mechanical Durability in Ternary Solar Cells Enabled by Low-Cost Incompletely Separated Fullerenes.

All-polymer solar cells (all-PSCs) are one of the most promising application-oriented organic photovoltaic technologies due to their excellent operational and mechanical stability. However, the power conversion efficiencies (PCEs) are mostly lower than 16%, restricting their core competitiveness. Furthermore, the improvement of mechanical durability is rarely paid attention to cutting-edge all-PSCs. This work deploys a low-cost "technical grade" PCBM (incompletely separated but pure mixtures containing ≥90% [70]PCBM or [60]PCBM), into the efficient PM6:PY-IT all-polymer blend, successfully yielding a high-performance ternary device with 16.16% PCE, among the highest PCE values for all-PSCs. Meanwhile, an excellent mechanical property (i.e., crack onset strain = 11.1%) promoted from 9.5% for the ternary system is also demonstrated. The "technical grade" PCBM slightly disrupts the crystallization of polymers, and disperses well into the amorphous polymer regions of the all-PSC blends, thus facilitating charge transport and improving film ductility simultaneously. All these results confirm introducing low-cost "technical grade" PCBM with high electron mobility into all-polymer blends can improve carrier mobility, reduce charge recombination, and optimize morphology of the amorphous polymer regions, thus yielding more efficient and mechanically durable all-PSCs.

Surface Passivation of Sputtered NiO x Using a SAM Interface Layer to Enhance the Performance of Perovskite Solar Cells.

Sputtered NiOx (sp-NiOx) is a preferred hole transporting material for perovskite solar cells because of its hole mobility, ease of manufacturability, good stability, and suitable Fermi level for hole extraction. However, uncontrolled defects in sp-NiOx can limit the efficiency of solar cells fabricated with this hole transporting layer. An interfacial layer has been proposed to modify the sp-NiOx/perovskite interface, which can contribute to improving the crystallinity of the perovskite film. Herein, a 2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz) self-assembled monolayer was used to modify an sp-NiOx surface. We found that the MeO-2PACz interlayer improves the quality of the perovskite film due to an enlarged domain size, reduced charge recombination at the sp-NiOx/perovskite interface, and passivation of the defects in sp-NiOx surfaces. In addition, the band tail states are also reduced, as indicated by photothermal deflection spectroscopy, which thus indicates a reduction in defect levels. The overall outcome is an improvement in the device efficiency from 11.9% to 17.2% due to the modified sp-NiOx/perovskite interface, with an active area of 1 cm2 (certified efficiency of 16.25%). On the basis of these results, the interfacial engineering of the electronic properties of sp-NiOx/MeO-2PACz/perovskite is discussed in relation to the improved device performance.

Important role of alloyed polymer acceptor for high efficiency and stable large-area organic photovoltaics

We developed high performance PM6:N3 bulk-heterojunctions by synthesizing polymers as the second acceptor. The acceptor PY-P2 where a biphenyl linker makes the polymer chain to have high dihedral angles forms intricate alloy-like composites in N3 domains whereas stiff polymer chain of PY-T2 exists separated from the acceptor domain. Introduction of PY-P2 results in much longer lifetimes and diffusion lengths of excitons generated in N3 domain of the PM6:N3:PY-P2 blend compared to those of the excitons in PM6:N3 as well as PM6:N3:PY-T2. Consequently, the PM6:N3:PY-P2 based OPV devices show improved exciton dissociation and change transport with reduced charge recombination. The PM6:N3:PY-P2 organic photovoltaic (OPV) devices prepared with blade-coating at 1 cm2 active area achieved efficiency of 15.2% compared with 12.9% of the PM6:N3 control device; whereas, the corresponding OPV device using PY-T2 shows decreased efficiency of 11.7%. OPV mini-module (active area 5.4 cm2) with PY-P2 achieves high efficiency of 14.7% compared with 11.9% of the PM6:N3 devices. Furthermore, the alloyed PY-P2 acceptor effectively improves OPV thermal stability under 85 °C heating for 1000 h, compared with PY-T2 and control devices. We demonstrated importance of the second polymer acceptor for achieving high-performance large-area OPV, which is significantly affected by its chemical structure.

Naphthobisthiadiazole-Based π-Conjugated Polymers for Nonfullerene Solar Cells: Suppressing Intermolecular Interaction Improves Photovoltaic Performance.

Naphthobisthiadiazole has been known as a promising building unit of π-conjugated polymers for organic photovoltaics (OPVs). Here, we synthesized new NTz-based polymers that were combined with a benzodithiophene (BDT) unit having alkylthienyl substituents in the polymer backbone, named PNTzBDT, and PNTzBDT-F and PNTzBDT-Cl with fluorine and chlorine groups in the substituents, respectively. The polymers had significantly improved solubility than the previously reported NTz-based polymer (PNTz4T), most likely due to the torsion of the alkylthienyl substituents with respect to the BDT moiety, which suppresses the intermolecular interaction between the backbones. Despite the lower intermolecular interaction and thereby lower crystallinity, these polymers, in particular PNTzBDT and PNTzBDT-F, exhibited higher photovoltaic performances, with power conversion efficiencies as high as 13.3%, than PNTz4T in the cells that used Y6 as the acceptor material. The improved performance was ascribed to the enhanced miscibility of the polymers with the nonfullerene acceptor due to the increased solubility, which in addition led to the better charge generation and reduced charge recombination. These results indicate that NTz-based π-conjugated polymers have high potential for nonfullerene-based OPVs.

Reducing Energy Disorder in Perovskite Solar Cells by Chelation.

In inverted perovskite solar cells (PSCs), the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is a widely used electron transport material. However, a high degree of energy disorder and inadequate passivation of PCBM limit the efficiency of devices, and severe self-aggregation and unstable morphology limit the lifespan of devices. Here, we design a series of fullerene dyads FP-Cn (n = 4, 8, 12) to replace PCBM as an electron transport layer, where [60]fullerene is linked with a terpyridine chelating group via a flexible alkyl chain of different lengths as a spacer. Among three fullerene dyads, FP-C8 shows the most enhanced molecule ordering and adhesion with the perovskite surface due to the balanced decoupling between the chelation effect from terpyridine and the self-assembly of fullerene, leading to lower energy disorder and higher morphological stability relative to PCBM. The FP-C8/C60-based devices using Cs0.05FA0.90MA0.05PbI2.85Br0.15 as a light absorber show a power conversion efficiency of 21.69%, higher than that of PCBM/C60 (20.09%), benefiting from improved electron extraction and transport as well as reduced charge recombination loss. When employing FAPbI3 as a light absorber, the FP-C8/C60-based devices exhibit an efficiency of 23.08%, which is the champion value of inverted PSCs with solution-processed fullerene derivatives. Moreover, the FP-C8/C60-based devices show better moisture and thermal stability than PCBM/C60-based devices and maintain 96% of their original efficiency after 1200 h of operation, while their counterpart PCBM/C60 maintains 60% after 670 h.

Multifunctional Additive of Potassium Cinnamate Improve Crystallization and Passivate Defect for Perovskite Solar Cell with Efficiency Exceeding 22%

Perovskites with high film quality and low defect density are considered the essential condition for obtaining high‐performance perovskite devices. Herein, a simple and effective multifunctional additive of potassium cinnamate (PC) is doped into a perovskite precursor solution to improve the film quality and passivate the defect. It is revealed that the PC additives can react with the perovskite compositions, which affect the crystallization of perovskite and eventually form a high‐quality perovskite film. In addition, the PC additive still exists in the perovskite film after annealing, which effectively passivates the defects in perovskites. It is found that the PC‐doped devices exhibit improved photoluminescence intensity, increased carrier lifetimes, and reduced charge recombination. As a result, due to the improvement of film quality and efficient defect passivation, the doped device delivers a champion photoelectric conversion efficiency of 22.00%, which is significantly higher than 18.96% of the pristine device. The doped device maintains 86% of its maximum efficiency after aging for 5 months, which significantly improves long‐term stability compared to 62% of the original device. Herein, a new idea for designing efficient additives is provided to further enhance the performance and stability of perovskite solar cells.