Improved Power Conversion Efficiency Research Articles

Morphology manipulation of photoactive layer through block copolymer to improve the photovoltaic performances of polymer solar cells

Additive treatment is an effective method for manipulating the bulk heterojunction (BHJ) photoactive layer morphology of polymer solar cells (PSCs). In this work, block copolymer, polystyrene-block-poly(acrylic acid) (PS-b-PAA), was elaborately selected (according to Flory–Huggins theory) as an additive for active layer to manipulate the BHJ morphology and to enhance the photovoltaic performance of devices. As results, with a PS-b-PAA concentration of 0.4 mg/ml, the corresponding devices achieve a significant power conversion efficiency (PCE) improvement to 13.08%. By systematically analysis, the improved PCE can be ascribed to more appreciate phase separation induced by incorporation of PS-b-PAA. For the instance of the photovoltaic physical process, more suitable morphology can induce improved charge transport efficiency, suppressed bimolecular recombination and monomolecular recombination or trap-assisted recombination. In comparing, the photovoltaic performance of devices with PS-b-PAA is obviously better than that of devices with insulating polymer polystyrene (PS) and polyacrylic acid (PAA). Hence, this work checks the morphology manipulation effects of block copolymer PS-b-PAA and provides an effective and facile method to improve the morphology and photovoltaic performances of PSCs.

Interfacial Engineering of a PCBM/AZO Electron Transport Bilayer for Efficient and Stable Inverted Perovskite Solar Cells

AbstractThe reduced hysteresis index and low‐temperature processed fabrication of inverted p‐i‐n perovskite solar cells (PSC) have attracted substantial attraction for achieving higher photovoltaic performance through interfacial engineering. Despite having certain limitations, fullerene‐based electron transport layers have been used frequently utilized in mixed halide inverted perovskite solar cells. The energy level mismatch between PCBM and metal electrode creates a hindrance in efficient electron extraction and thus a limiting factor in attaining higher device performances. In this work, we report an efficient interlayer of aluminum‐doped zinc oxide (AZO) nanoparticles in‐between PCBM and the metal electrode to suppress interfacial recombination. The PCBM/AZO electron transport bilayer can effectively mitigate the imperfections of the PCBM layer alone. The PCBM/AZO electron transport bilayer with an optimal concentration of 2% Al dopant exhibited greatly improved power conversion efficiency (PCE) of 18.63%, VOC of 1.13 V, and FF of 73% with negligible hysteresis index of 0.04. Further, the optimal device exhibited remarkable stability by retaining 91% of the initial PCE after 200 hours confirming the suitable insertion of the AZO bilayer. The improved photovoltaic performance using PCBM/AZO bilayer can be attributed to higher electron transfer efficiency, suppressed interfacial recombination, and smooth surface morphology of AZO nanoparticles atop the PCBM layer.

Pressure-Induced Band Gap Engineering of Nontoxic Lead-Free Halide Perovskite CsMgI3 for Optoelectronic Applications.

Recently, lead halide perovskites have gained considerable attention by dint of their predominant physiochemical features and potential use in various applications with an improved power conversion efficiency. Despite the incredible technological and research breakthroughs in this field, most of those compounds present an obstacle to future commercialization due to their instability and extreme poisonousness. Because of this, it is preferable to replace lead with alternative stable elements to produce eco-friendly perovskites with equivalent optoelectronic qualities similar to lead-based perovskites. However, Pb-free perovskite-based devices have relatively low power conversion efficiency. Pressure might be considered an effective way for modifying the physical characteristics of these materials to enhance their performance and reveal structure-property correlations. The present study has been done to investigate the structural, electronic, optical, elastic, mechanical, and thermodynamic properties of nontoxic perovskite CsMgI3 under hydrostatic pressure by using density functional theory (DFT). At ambient pressure, the present findings are in excellent agreement with the available experimental data. Pressure causes the Mg-I and Cs-I bonds to shorten and become stronger. The absorption coefficient in the visible and ultraviolet (UV) zones grows up with the increase in pressure. Additionally, we have observed low reflectivity, a high-intensity conductivity peak, and a dielectric constant in the visible region of the electromagnetic spectrum. As pressure rises, the band gap keeps narrowing, facilitating an electron from the valence band to get excited easily at the conduction band. Furthermore, we analyze the mechanical, elastic, and thermodynamic properties under pressure, which suggests that this compound exhibit ductile behavior. The shrunk band gap and improved physical properties of CsMgI3 under hydrostatic pressure suggest that this material may be used in solar cells (for photovoltaic applications) and optoelectronic devices more frequently than at ambient pressure. In addition, this paper emphasizes the feasibility of hydrostatic pressure in the systematic modification of the optoelectronic and mechanical characteristics of lead-free halide perovskites.

Thermally stable and efficient CsF-doped All-Inorganic CsPbIBr2 perovskite solar cells exceeding 15% PCE

Different strategies such as interface modification, cell encapsulation, perovskite doping, etc., are employed to address the different types of stability issues in perovskite solar cells. In this research, we used cesium fluoride (CsF) as a doping material to optimize the formation of CsPbIBr2 film and investigate its effect on the thermal stability of the devices. Our findings show that CsF diffuses into CsPbIBr2 seed film successfully and greatly enhances the stability of perovskite solar cells under study. Furthermore, compared to the reference device without doping, CsF-doped devices were found to have reduced trap state density, suppressed recombination of carriers, enhanced crystallinity, and improved power conversion efficiency from 13.15 to 15.54%. The study provides important pathways to fabricate highly stable perovskites thin films for all-in-organic solar cells.

In Situ Iodide Passivation Toward Efficient CsPbI3 Perovskite Quantum Dot Solar Cells

HighlightsThe introduction of hydroiodic acid (HI) manipulates the dynamic conversion of PbI2 into highly coordinated species to optimize the nucleation and growth kinetics.The addition of HI enables the fabrication of CsPbI3 perovskite quantum dots with reduced defect density, enhanced crystallinity, higher phase purity, and near-unity photoluminescence quantum yield.The efficiency of CsPbI3 perovskite quantum dot solar cells was enhanced from 14.07% to 15.72% together with enhanced storage stability.All-inorganic CsPbI3 quantum dots (QDs) have demonstrated promising potential in photovoltaic (PV) applications. However, these colloidal perovskites are vulnerable to the deterioration of surface trap states, leading to a degradation in efficiency and stability. To address these issues, a facile yet effective strategy of introducing hydroiodic acid (HI) into the synthesis procedure is established to achieve high-quality QDs and devices. Through an in-depth experimental analysis, the introduction of HI was found to convert PbI2 into highly coordinated [PbIm]2−m, enabling control of the nucleation numbers and growth kinetics. Combined optical and structural investigations illustrate that such a synthesis technique is beneficial for achieving enhanced crystallinity and a reduced density of crystallographic defects. Finally, the effect of HI is further reflected on the PV performance. The optimal device demonstrated a significantly improved power conversion efficiency of 15.72% along with enhanced storage stability. This technique illuminates a novel and simple methodology to regulate the formed species during synthesis, shedding light on further understanding solar cell performance, and aiding the design of future novel synthesis protocols for high-performance optoelectronic devices.

Improving Power Conversion Efficiency of P3HT/PCBM based Organic Solar Cells by Optimizing Graphene Doping Concentration and Annealing Temperature

Improving Power Conversion Efficiency of P3HT/PCBM based Organic Solar Cells by Optimizing Graphene Doping Concentration and Annealing Temperature

Surface defect passivation of All-Inorganic CsPbI2Br perovskites via fluorinated ionic liquid for efficient Outdoor/Indoor photovoltaics processed in ambient air

All-inorganic α-CsPbI2Br perovskite has garnered considerable interest due to its optical bandgap (∼1.92 eV) suitable for tandem architectures and superior thermal stability. However, CsPbI2Br based perovskite solar cells (PSCs) exhibit severe energy loss due to presence of various surface defects like uncoordinated Pb2+ ions, halide ion vacancies and pinholes, which causes serious non-radiative recombination and limit the further improvement in power conversion efficiency (PCE). Surface passivation strategy is an effective approach to produce high quality α-CsPbI2Br film. Herein, we introduce fluorinated ionic liquid, 3-(Trifluoromethyl) benzylamine (CFBA), as surface passivating agent. The chemical analysis shows that the trifluoro (-CF3) and amine groups of CFBA strongly interacted with perovskite surface via forming Pb-F and H-I bonding, respectively. The high electronegative fluoride atoms of -CF3 group allow for electrostatic interaction with uncoordinated Pb2+ ions, which built a robust shield that protected against surrounding moisture as well. In addition, CFBA modification passivates the dangling bonds, enhanced crystallinity, reduced pinholes, improved the surface coverage and compactness, increased hydrophobicity, and decreased non-radiative recombination, leading to high PCE. With optimum concentration of 3 μL-CFBA, CsPbI2Br PSC revealed an impressive PCE of 17.07% with FF of 83.21% as compared to pristine device (PCE of 15.24% with FF of 79.81%). Moreover, champion device showed an excellent thermal stability by retaining ∼ 86.23% of its initial PCE, whereas pristine device maintained ∼ 48.26% of its original PCE after 1440 h aging at 85 ℃ in a dry box without any encapsulation. In addition, optimized PSC showed a decent indoor PCE of 23.24% as compared to pristine device (18.35%) under dim lighting conditions (LED, 3200 K) at 1000 lx. These results suggested that surface passivation strategy with CFBA is a promising approach for developing efficient all-inorganic CsPbI2Br outdoor/indoor PSCs with better thermal stability.

P‐Type Doping of PM6:Y6‐Based Photoactive Layer with Formic Acid

The introduction of molecular doping process is necessary to enhance the optic and electronic properties of organic semiconductors for facilitating charge transport. In particular, since the doping process has a positive influence on the charge transfer interaction between host semiconductor and dopant, improved mobility has been efficiently achieved. Despite its advantages, doping technologies in organic solar cells (OSCs) are emphasized to the development of n‐type dopants used for balancing the electron and hole. In addition, since the bulk‐heterojunction microstructure in OSCs has randomly blended phases of the donor and acceptor, it is important to optimize charge extraction without loss by controlling the morphology. Herein, OSCs by p‐type doping with formic acid (FA) into a photoactive layer is reported. The champion device yields a significantly improved power conversion efficiency from 14.3% to 15.3% with a high fill factor of 71.7%. It is found that the p‐doped photoactive layer exhibits enhanced conductivity, improved carrier mobilities, suppressed charge recombination, and lowered leakage current. The FA simultaneously acts as a film morphology controller of the photoactive layer with enhanced phase separation to transport the charge efficiently. Thus, the doping process with FA can maintain the device performance in stability tests (95.6% remaining).

Enhanced photovoltaic performance of dye-sensitized solar cells using innovative bithienylnicotinonitrile-based organic dyes

This exciting study introduces five cutting-edge bithienylnicotinonitrile-based organic dyes (coded GA-1-5) that were specifically synthesized for use in dye-sensitized solar cells (DSSCs). These dyes boast a D-π-A framework and were designed to manipulate spectral properties and energy levels. The researchers conducted a comprehensive analysis of their optical, electrochemical, photovoltaic, geometrical, and electronic characteristics using both experimental and theoretical methods. The dyes exhibited intense UV–vis absorption with high molar extinction coefficients, making them ideal co-sensitizers for ruthenium-based DSSCs. When tested, the co-sensitized devices demonstrated significantly improved power conversion efficiencies (PCEs) ranging from 6.22% to 9.12%, thanks to their enhanced short-circuit photocurrents (Jsc), which surpassed those of DSSCs sensitized with N3 alone (PCE = 6.20%). Additionally, GA-1-5 compensated for the photocurrent loss caused by I−/I3 in co-sensitization, further improving the Jsc. We also carried out various spectral and electrochemical characterizations to gain a better understanding of the underlying mechanisms. These findings represent a significant advancement in the field of solar cell technology, paving the way for more efficient and sustainable energy solutions.

Synergistic Defect Passivation by Metformin Halides for Improving Perovskite Solar Cell Performance

Defect passivation plays a critical role in manufacturing high-performance perovskite solar cells (PSCs). Herein, engineered components of metformin halides are introduced to the bulk and surface of perovskite layers in PSCs to realize synergistic defect passivation. It is found that the bulk addition of metformin hydrochloride influences the orientation distribution of perovskite crystals and contributes to better perovskite films. Further, the modification of metformin iodide could treat residual defects on the surface of perovskite films. As a result, the synergistically passivated PSCs shows an improved power conversion efficiency (PCE), which increased from 19.36% to 22.17%, together with a higher short-circuit current and open-circuit voltage than those of the control device. Moreover, the as-treated PSCs exhibit excellent thermal and humidity stabilities, maintaining 95% of their initial PCE after being stored under air conditions for over 1000 h. This work provides a novel strategy to passivate perovskite defects and improve the PCE and stability of PSCs.

Reducing damage of sputtering and improving conductivity of transparent electrodes for efficient semi-transparent perovskite solar cells

Sputtered indium tin oxide (ITO) is widely used as an electrode in semi-transparent and tandem perovskite solar cells. However, damage from sputtering to under layers and the limited conductivity of ITO are still the two main obstacles that hinder further performance improvement of the devices. In this work, the effects and mechanism of sputtering damage and poor conductivity of ITO are investigated based on a traditional perovskite solar cell with bathocuproine (BCP) buffer layer. In order to suppress the sputtering damage, tin oxide (SnO2) is deposited on C60 to replace the BCP buffer layer. However, it is found that the deposition of SnO2 on the non-reactive C60 by atomic layer deposition will result in island growth of SnO2 film, which is the key reason for large dark current in solar cells. Fortunately, the phenomenon is inhibited by decorating C60 surface with WO3 thin film. In order to improve the conductivity of the transparent electrode, an ITO/Au/ITO multilayer architecture is designed. The fill factor (FF) and power conversion efficiency (PCE) of the semi-transparent solar cells (ST-PSCs) with the modified buffer layer and electrodes reached 76.4% and 17.62%, respectively, showing an improvement of FF and PCE when compared to the device with BCP buffer layer and ITO electrode. It is revealed that the optimization also increases the short circuit current of the solar cells. These results provide new strategies for damage reduction of sputtering and performance improvement of ST-PSCs.

Collaborative interfacial modification and surficial passivation for high-efficiency MA-free wide-bandgap perovskite solar cells

The wide-bandgap (WBG) perovskite solar cells (PSCs) are the pivotal component for the tandem solar cells, which provides a potential for exceeding the theoretical power conversion efficiency (PCE) limit of the single-junction solar cells. However, the improvement of PCE for perovskite/silicon tandem solar cells is restricted by the interfacial transport barrier loss and the nonradiative recombination loss of the WBG-PSC top cell. Herein, we applied methylammonium-free (MA-free) WBG perovskite for achieving an excellent stability light absorber. This work offers a simultaneous interfacial modification and surficial passivation strategy for suppressing the losses of interfacial barrier and recombination. The mixture of [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and [2-(3,6-dimeth oxy-9H-carbazol-9-yl)ethyl]phosphonic acid (Meo-2PACz) as a self-assembled monolayer (SAM) is employed to facilitate the carrier transport from the perovskite to the anode. 4-trifluoromethyl-phenylammonium iodine (CF3PhAI) is introduced to passivate the surface defect of perovskites. Therefore, the open circuit voltage and PCE of the WBG-PSC are significantly increased. The opaque and transparent electrode (TE) PSCs achieve PCEs of 20.11% and 17.80%, respectively, and the unencapsulated opaque PSC retains more than 85% of the initial efficiency after 1750 h in N2-glovebox. The four-terminal tandem solar cell with perovskite and silicon absorbers was fabricated and obtained 26.59% efficiency. This work provides a simple way to improve the PCE and stability of WBG-PSCs, facilitating the development of tandem solar cells.

A Coaxial Pulsed Plasma Thruster Model with Efficient Flyback Converter Approaches for Small Satellites

Pulsed plasma thrusters (PPT) have demonstrated enormous potential since the 1960s. One major shortcoming is their low thrust efficiency, typically <30%. Most of these losses are due to joule heating, while some can be attributed to poor efficiency of the power processing units (PPUs). We model PPTs to improve their efficiency, by exploring the use of power electronic topologies to enhance the power conversion efficiency from the DC source to the thruster head. Different control approaches are considered, starting off with the basic approach of a fixed frequency flyback converter. Then, the more advanced critical conduction mode (CrCM) flyback, as well as other optimized solutions using commercial off-the-shelf (COTS) components, are presented. Variations of these flyback converters are studied under different control regimes, such as zero voltage switching (ZVS), valley voltage switching (VVS), and hard switched, to enhance the performance and efficiency of the PPU. We compare the max voltage, charge time, and the overall power conversion efficiency for different operating regimes. Our analytical results show that a more dynamic control regime can result in fewer losses and enhanced performance, offering an improved power conversion efficiency for PPUs used with PPTs. An efficiency of 86% was achieved using the variable frequency approach. This work has narrowed the possible PPU options through analytical analysis and has therefore identified a strategic approach for future investigations. In addition, a new low-power coaxial micro-thruster model using equivalent circuit model elements is developed.This is referred to as the Carlow–Stuttgart model and has been validated against experimental data from vacuum chamber tests in Stuttgart’s Pulsed Plasma Laboratory. This work serves as a valuable precursor towards the implementation of highly optimized PPU designs for efficient PPT thrusters for the next PETRUS (pulsed electrothermal thruster for the University of Stuttgart) missions.

Stabilized Perovskite Quantum Dot Solids via Nonpolar Solvent Dispersible Covalent Ligands.

The ligand exchange procedure of CsPbI3 perovskite quantum dots (PQDs) enables the fabrication of thick and conductive PQD solids that act as a photovoltaic absorber for solution-processed thin-film solar cells. However, the ligand-exchanged CsPbI3 PQD solids suffer from deterioration in photovoltaic performance and ambient stability due to the surface traps, such as uncoordinated Pb2+ sites on the PQD surface, which are generated after the conventional ligand exchange process using ionic short-chain ligands dissolved in polar solvents. Herein, a facile surface stabilization is demonstrated that can simultaneously improve the photovoltaic performance and ambient stability of CsPbI3 PQD photovoltaic absorber using covalent short-chain triphenylphosphine oxide (TPPO) ligands dissolved in a nonpolar solvent. It is found that the TPPO ligand can be covalently bound to uncoordinated Pb2+ sites and the nonpolar solvent octane can completely preserve the PQD surface components. Owing to their synergetic effects, the CsPbI3 PQD photovoltaic absorber stabilized using the TPPO ligand solution dissolved in octane exhibit higher optoelectrical properties and ambient stability than the control absorber. Consequently, CsPbI3 PQD solar cells composed of PQD photovoltaic absorbers fabricated via surface stabilization strategy provide an improved power conversion efficiency of 15.4% and an enhanced device stability.

Contact Engineering and In Situ Formation of 2D Perovskite Via Solid‐Phase Growth for Efficient Hole‐Transport‐Layer‐Free Perovskite Solar Cells

Perovskite Solar Cells In article number 2300020, Congcong Wu, Haijin Li, and co-workers present a contiguous contact of perovskite/carbon interface achieved by in situ formation of 2D perovskite through a solid phase reaction when fabricating a carbon electrode. The 2D perovskite interlayer not only passivates surface defects but also enables a seamless contact at the perovskite/carbon interface and promotes carrier transport, thereby improving power conversion efficiency and stability of hole-transport-layer-free perovskite solar cells simultaneously.

Syntheses of efficient nickel oxide film by low-temperature fabrication technique for high-performance perovskite solar cells

Interface modification is an effective technique to improve power conversion efficiency (PCE) of perovskite solar cells (PSCs). In this study, three kinds of hole transport layers (HTLs), including planar-nickel oxide (P-NiOx) film, surface-nanostructured-NiOx (S-NiOx) film, and modified-NiOx (M-NiOx) film, are synthesized by low-temperature fabrication technique. Furthermore, M-NiOx film is defined by modifying P-NiOx film with ultra-low concentration NiOx nanoparticles. The results show that the M-NiOx film has higher conductivity and carrier transport ability than those of P-NiOx and S-NiOx. The special morphology of M-NiOx film is beneficial to improving the crystallinity of MAPbI3 perovskite film. Thus, the PSC based on M-NiOx film exhibits the highest short-circuit current density (Jsc) of 21.30 mA cm−2, which is larger than those of PSCs based on P-NiOx (17.74 mA cm−2) and S-NiOx films (16.56 mA cm−2). The optimized PSC based on M-NiOx film exhibits the high photovoltaic performance with PCE of 16.67%. The optimized PSC with M-NiOx film shows a long-term stability. After storing in a nitrogen-filled glove box for 1000 h, the PSC with M-NiOx film still has 85% of its initial PCE.

Perovskite interface defect passivation with poly(ethylene oxide) for improving power conversion efficiency of the inverted solar cells.

Inverted perovskite solar cells (PSCs) attract researchers' attention for their potential application due to the low-temperature fabrication, negligible hysteresis and compatibility with multi-junction cells. However, the low-temperature fabricated perovskite films containing excessive undesired defects are not benefit for improving the performance of the inverted PSCs. In this work, we used a simple and effective passivation strategy that Poly(ethylene oxide) (PEO) polymer as an antisolvent additive to modify the perovskite films. The experiments and simulations have shown that the PEO polymer can effectively passivate the interface defects of the perovskite films. The defect passivation by PEO polymers suppressed non-radiative recombination, resulting in an increase in power conversion efficiency (PCE) of the inverted devices from 16.07% to 19.35%. In addition, the PCE of unencapsulated PSCs after PEO treatment maintains 97% of its original stored in a nitrogen atmosphere for 1000 h.

Interface Engineering Enhances the Photovoltaic Performance of Wide Bandgap FAPbBr3 Perovskite for Application in Low‐Light Environments

AbstractUnderwater solar cells (UWSCs) provide an ideal alternative to the energy supply for long‐endurance autonomous underwater vehicles. However, different from conventional solar cells situated on land or above water, UWSCs give preference to use wide bandgap semiconductors (≥1.8 eV) as light absorber to match underwater solar spectra. Among wide bandgap semiconductors, FAPbBr3 perovskite is under prime consideration owing to its matching optical bandgap (≈2.3 eV), outstanding photoelectric properties, easier processability, etc. Unfortunately, for FAPbBr3 solar cells, substantial interface defects greatly limit the charge carrier extraction efficiency, thus limiting the device performance, especially in underwater low‐light environments. This study employs a molecular self‐assembly strategy to effectively eliminate the interfacial defects. As a result, a great improvement in power conversion efficiency (PCE) from 6.44% to 7.49% is obtained, which is among the best efficiency reported for inverted FAPbBr3 solar cells up to date. Besides, a champion PCE of 30% is obtained under 520 nm monochromatic light irradiation (4.8 mW cm−2). These results demonstrate that FAPbBr3 solar cells present a tremendously promising application in UWSCs.

Improved Power Conversion Efficiency and Stability of Perovskite Solar Cells Induced by Molecular Interaction with Poly(ionic liquid) Additives.

Ionic liquid (IL) additives proved to have a positive effect on the device efficiency and stability of perovskite solar cells. However, since ILs are small molecules and undergo Coulomb interactions, they can easily aggregate and evaporate over long times, which would cause instabilities during a long-term device operation. To overcome these problems, we polymerize ILs into macromolecules and incorporate them into perovskite films as well as into the corresponding solar cells. Both cations and anions of the used poly[1-(2-acryloylethyl)-3-methylimidazolium] bis (trifluoromethane) sulfonamides (PAEMI-TFSIs) are designed to coordinate with the Pb and I of PbI62- octahedra, respectively, which changes the crystallization behavior of the perovskite films. Importantly, the PAEMI-TFSI efficiently passivates electronic defects on the grain boundaries and thereby enhances the charge-carrier transport in the perovskite film. As a result, PAEMI-TFSI-modified MAPbI3 solar cells show a high power conversion efficiency of 22.4% and an excellent storage stability (92% of the initial efficiency remains after 1200 h operation in a nitrogen atmosphere for nonencapsulated devices).

Boosting the Performance of Perovskite Solar Cells through Systematic Investigation of the Annealing Effect of E-Beam Evaporated TiO2.

Electron transport layer (ETL) plays an undeniable role in improving the performance of n-i-p planar perovskite solar cells (PSCs). Titanium dioxide (TiO2) is known as a promising ETL material for perovskite solar cell. In this work, the effect of annealing temperature on optical, electrical, and surface morphology of the electron-beam (EB)-evaporated TiO2 ETL, and consequently on the performance of perovskite solar cell, was investigated. It was found that annealing treatment at an optimized temperature of 480 °C considerably improved the surface smoothness, density of grain boundaries, and carrier mobility of TiO2 film, which resulted in nearly 10-fold improvement in power conversion efficiency (11.16%) in comparison with the unannealed device (1.08%). The improvement in performance of the optimized PSC is attributed to the acceleration of charge carrier extraction, as well as suppression of the recombination at the ETL/Perovskite interface.