Interface Modification Layer Research Articles

Self‐Assembly Metal Chelate as Ultraviolet Filterable Interface Layer for Efficient Organic Solar Cells

AbstractInterface engineering plays a vital role in the further improvement of efficiency and stability for organic solar cells (OSCs). Herein, a self‐assembly metal chelate based on hafnium and a designed ligand, N‐(4‐(3‐oxobutanoyl)phenyl)acetamide (ACBN) is applied as both interfacial modification layer and UV‐light filter in OSCs. The strong hydrogen‐bond induced intermolecular interaction enables Hf(ACBN)4 with the prerequisite of adequate solvent resistance to work as an electron transport layer (ETL) in the inverted OSCs. The self‐assembly behavior of Hf(ACBN)4 on the SnO2 film surface via constructing compact coordination structure has been verified via systematic theory calculations. In addition to optimizing the energy level alignment, the Hf(ACBN)4 modification effectively passivates the surface defect of SnO2 films for less surface charge recombination and a more efficient charge collection process. Thus, the OSCs with Hf(ACBN)4 layer yield a maximum PCE of 18.1%, better than that based on the bare SnO2 layer. Moreover, beneficial from the reduced oxygen vacancies via coordination effect and the UV‐light filter function of Hf(ACBN)4, the OSCs based on SnO2/ Hf(ACBN)4 composite ETL exhibit preferable stabilities under UV‐light irradiation or continuous operational conditions.

In Situ Construction of a LiF-Enriched Interfacial Modification Layer for Stable All-Solid-State Batteries.

All-solid-state batteries (ASSBs), particularly based on sulfide solid-state electrolytes (SSEs), are expected to meet the requirements of high-energy-density energy storage. However, the unstable interface between the ceramic pellets and lithium (Li) metal can induce unconstrained Li-dendrite growth with safety concerns. Herein, we design a carbon fluoride-silver (CFx-Ag) composite to modify the SSEs. As lithium fluoride (LiF) nanocrystals can be in situ formed through electrochemical reactions, this LiF-enriched modification layer with high surface energy can more effectively suppress Li dendrite penetration and interfacial reactions between the SSEs and anode. Remarkably, the all-solid-state symmetric cells using a lithium-boron alloy (LiB) anode can stably work to above 2,500 h under 0.5 mA cm-2 and 2 mAh cm-2 at 60 °C without shorting. A modified LiB||LiNi0.6Mn0.2Co0.2O2 (NMC622) full cell also demonstrates an improved capacity retention and high Coulombic efficiency (99.9%) over 500 cycles. This work provides an advanced solid-state interface architecture to address Li-dendrite issues of ASSBs.

High-performance bulk heterojunction-based photocathode with facile architecture for photoelectrochemical water splitting

Organic semiconductors are promising candidates as photoactive layers for photoelectrodes used in photoelectrochemical (PEC) cells due to their excellent light absorption and efficient charge transport properties with the help of interfacial materials. However, the use of multilayers will make the charge transfer mechanism more complicated and decrease the PEC performance of the photoelectrode caused by the increased contact resistance. In this work, a PM6:Y6 bulk heterojunction (BHJ)-based photocathode is fabricated for efficient PEC hydrogen evolution reaction (HER) in an acidic aqueous solution. With RuO2 as an interfacial modification layer, the photocathode with a simple structure (fluorine-doped tin oxide (FTO)/PM6:Y6/RuO2) generates a maximum photocurrent density up to −15 mA/cm2 at 0 V vs. reference hydrogen electrode (RHE), outperforming all previously reported BHJ-based photocathodes in terms of PEC performance. The highest ratiometric power-saved efficiency of 3.7% is achieved at 0.4 V vs. RHE.

Hydrothermal Synthesis of Nitrogen and Phosphorus Co-Doped Carbon Dots Interfacial Modification Layer for Efficient Charge Transfer between ZnO Electron Transport Layer and PTB7:PC <sub>70</sub>BM Active Layer

Hydrothermal Synthesis of Nitrogen and Phosphorus Co-Doped Carbon Dots Interfacial Modification Layer for Efficient Charge Transfer between ZnO Electron Transport Layer and PTB7:PC <sub>70</sub>BM Active Layer

A Zn ion hybrid capacitor with enhanced energy density for anode-free

Aqueous zinc-based energy storage system plays an increasingly important role in the energy storage field because of the low cost, high safety, and high capacity. At present, zinc-based cells developed use excessive zinc, which increases volume and mass and sacrifices some energy density. The anode-free construction is realized by effective interface modification layer to address these issues. Nitrogen doped porous carbon nanocages modulation layer facilitates the uniform distribution of electric field, promote the uniform transport of zinc ions, further optimize nucleation and inhibit dendrite growth. This strategy can realize the homogeneous zinc nucleation and growth to obtain efficient and stable zinc plating/stripping. The Cu/NPCNs electrodes keep stable Zn plating/stripping of 100 cycles at large current density of 5 mA cm −2 and still maintain high CE (99%). Based on this anode-free foundation, an anode-free Zn ion capacitor exhibits high specific capacity of 106 mAh g-1 at 1 mA cm −2 and maintains high-capacity stability of 98% after 2000 cycles at 1 mA cm −2 . The energy density of 101 Wh kg −1 is higher than that of the zinc-metal anode system. This anode-free design strategy promotes the further development of zinc-based energy storage systems with high energy density. • A new type of anode-free Zn ion hybrid capacitor is constructed. • The interface strategy optimize Zn ion nucleation and inhibit Zn dendrite growth. • Theoretical calculations prove that NPCNs optimize transport kinetics of Zn ions. • The anode-free Zn ion hybrid capacitor exhibit increased energy density. • The anode-free Zn ion hybrid capacitor have excellent electrochemical performance.

Bifunctional ionic liquid for enhancing efficiency and stability of carbon counter electrode-based MAPbI3 perovskites solar cells

The potential of perovskite solar cells as a representative alternative to silicon-based solar cells has become significant owing to their unparalleled advancement in efficiency. However, the intrinsic instability of perovskite still hinders their large-scale commercial application, particularly of the decomposition of perovskite during device operation. To address this issue, an acetate-ion-functionalized polar ionic liquid, 1-allyl-3-methylimidazolium acetate (AMIMOAc), is used as an additive in MAPbI3 film. FTIR spectroscopy measurements show that AMIMOAc can anchor the organic cations via hydrogen bonding and enhance the Pb–O interaction in modified MAPbI3, leading to a continuous and dense morphology to increase the stability of MAPbI3. After optimizing the concentration of AMIMOAc, an additional interfacial modification layer accelerates the electron extraction and transport. By the synergy of both additive engineering and interface modification, the device not only achieves a high efficiency of 15.16%, but also maintains 93% of the initial PCE after 500 h, showing significantly improved stability. These results pave the way to a new strategy to improve efficiency and long-term stability of carbon counter electrode-based PSCs.

Coordinating light management and advance metal nitride interlayer enables MAPbI3 solar cells with >21.8% efficiency

Due to the continuous increase in power conversion efficiencies (PCEs), perovskite solar cells (PSCs) are widely considered as the most promising technology for third generation photovoltaics. Improving optical absorption while reducing electrical losses is still a challenge towards attaining PCE values closer to the Shockley-Queisser limit. However, frequently used strategies to improve light absorption (e.g. via texturing the front surface) often cause electrical recombination losses. Here, we successfully relaxed the competing mechanisms between electrical and optical properties by integrating a modulated textured substrate and an amorphous metal nitride interface modification layer to combine enhanced light scattering and reducing interfacial recombination losses in PSCs. This comprehensive electro-optical management presents several advantages, including increased light absorption, promoting bandgap alignment and passivating the underlying perovskite defects. Consequently, the resulting MAPbI3 solar cells exhibit a high open-circuit voltage of 1.17 V and the concomitant high PCE of 21.84%. In addition, we also use numerical simulations to propose approaches towards achieving high efficiency (PCE>30%) PSCs. Besides expanding the pool of available strategies for improving the efficiency of PSCs, from photon management to interface engineering, our work also offers a systematic guidance for the design and fabrication of high performance photovoltaic devices.

P-type tetrathiafulvalene derivative as the interface modification layer in non-fullerene organic solar cells with high performance

Interfacial layers between active layer and electrodes are essential for achieving high performance in organic solar cells. Herein, an effective anode interface modification material, TTF-PZ was synthesized and combined with PEDOT:PSS using as hole transporting bilayer. The bilayer-containing routine solar cell consists of PM6: Y6 bulk heterojunction delivered an increased PCE of 15.84% and an impressive Jsc of 26.19 mA/cm2. The underlying mechanisms of such improvement can be summarized as below: the optimization of the active layer morphology, effective charge extraction, and decreased charge recombination. This work confirms the possibility that TTF-PZ could be used as a hole transport material to obtain high performance in organic photovoltaic field.

Cooperative Shielding of Bi-Electrodes via In Situ Amorphous Electrode-Electrolyte Interphases for Practical High-Energy Lithium-Metal Batteries.

Solid-state Li-metal batteries offer a great opportunity for high-security and high-energy-density energy storage systems. However, redundant interfacial modification layers, intended to lead to an overall satisfactory interfacial stability, dramatically debase the actual energy density. Herein, a dual-interface amorphous cathode electrolyte interphase/solid electrolyte interphase CEI/SEI protection (DACP) strategy is proposed to conquer the main challenges of electrochemical side reactions and Li dendrites in hybrid solid-liquid batteries without sacrificing energy density via LiDFOB and LiBF4 in situ synergistic conversion. The amorphous CEI/SEI products have an ultralow mass proportion and act as a dynamic shield to cooperatively enforce dual electrodes with a well-preserved structure. Thus, this in situ DACP layer subtly reconciles multiple interfacial compatibilities and a high energy density, endowing the hybrid solid-liquid Li-metal battery with a sustainably brilliant cycling stability even at practical conditions, including high cathode loading, high voltage (4.5 V), and high temperature (45 °C) conditions, and enables a high-energy-density (456 Wh kg-1) pouch cell (11.2 Ah, 5 mA h cm-2) with a lean electrolyte (0.92 g Ah-1, containing solid and liquid phases). The compatible modification strategy points out a promising approach for the design of practical interfaces in future solid-state battery systems.

Surface modification of c-TiO2 via different phenyl boronic acid SAMs for improved performance of inverted organic solar cells

In this study, phenyl boronic acid (PBA) self-assembled monolayers (SAMs) with different terminal groups were introduced on c-TiO2, as interfacial modification layer in organic solar cells (OSCs) with inverted structure. The morphological, optical, electrical properties and the surface wettability of c-TiO2 layer were successfully tuned by SAMs modification. The all five SAMs introduced to device configuration improved the photovoltaic performances. The NO2-PBA SAM modified device exhibited a power conversion efficiency (PCE) of 3.4 % with a short‐circuit current density of 9.68 mA cm−2, an open‐circuit voltage of 0.59 V and fill factor of 48.46 %. More than 50 % enhancement on the PCE was achieved thanks to better ohmic contact and energy level alignment at the interface resulting improved charge collection. The surface properties can be changed by varying the terminal group of molecules, which can control the charge transport properties leading high shunt resistance and low series resistance. Our results showed that the PBA SAMs can be used as efficient interfacial modification layer for inverted OSCs.

Ultrathin Surface Coating of Nitrogen-Doped Graphene Enables Stable Zinc Anodes for Aqueous Zinc-Ion Batteries.

Owing to the high volumetric capacity and low redox potential, zinc (Zn) metal is considered to be a remarkably prospective anode for aqueous Zn-ion batteries (AZIBs). However, dendrite growth severely destabilizes the electrode/electrolyte interface, and accelerates the generation of side reactions, which eventually degrade the electrochemical performance. Here, an artificial interface film of nitrogen (N)-doped graphene oxide (NGO) is one-step synthesized by a Langmuir-Blodgett method to achieve a parallel and ultrathin interface modification layer (≈120nm) on Zn foil. The directional deposition of Zn crystal in the (002) planes is revealed because of the parallel graphene layer and beneficial zincophilic-traits of the N-doped groups. Meanwhile, through the in situ differential electrochemical mass spectrometry and in situ Raman tests, the directional plating morphology of metallic Zn at the interface effectively suppresses the hydrogen evolution reactions and passivation. Consequently, the pouch cells pairing this new anode with LiMn2 O4 cathode maintain exceptional energy density (164Whkg-1 after 178 cycles) at a reasonable depth of discharge, 36%. This work provides an accessible synthesis method and in-depth mechanistic analysis to accelerate the application of high-specific-energy AZIBs.

Simultaneous Improvement of Efficiency and Stability of Organic Photovoltaic Cells by using a Cross-Linkable Fullerene Derivative.

Improving power conversion efficiencies (PCEs) and stability are two main tasks for organic photovoltaic (OPV) cells. In the past few years, although the PCE of the OPV cells has been considerably improved, the research on device stability is limited. Herein, a cross-linkable material, cross-linked [6,6]-phenyl-C61-butyric styryl dendron ester (c-PCBSD), is applied as an interfacial modification layer on the surface of zinc oxide and as the third component into the PBDB-TF:Y6-based OPV cells to enhance photovoltaic performance and long-term stability. The PCE of the OPV cells that underwent the two-step modification increased from 15.1 to 16.1%. In particular, such OPV cells exhibited much better stability under both thermal and air conditions because of the decreased number of interfacial defects and stable interfacial and active layer morphologies. The results demonstrated that the introduction of a cross-linkable fullerene derivative into the interfacial and active layers is a feasible method to improve the PCE and stability of OPV cells.

Hybrid solar cells of Ru-based dye complexes as interfacial modification layers: Energy level alignment and photoelectric properties improvement

The chemical incompatibility at the organic-inorganic heterojunction interface in hybrid solar cells is a serious issue that cannot be ignored. In this work, four Ru-based dye complexes (D-series organic dyes) were employed for the interfacial properties modulation. The results showed that the introduction of organic molecules can not only improve the compatibility between the organic and inorganic materials, but also provide an appropriate energy levels alignment of the materials in the hybrid films. A notable power conversion efficiency of 2.91% was achieved. The intrinsic factors that affecting the cells performance were investigated by electrochemical impedance and open circuit voltage decay measurements.

Effect of inorganic interfacial modification layer on the performance of quantum-dots light-emitting diodes

Efficiency and operational durability are crucial characteristics for the high-performance quantum-dots light-emitting diodes (QLEDs). In order to improve the efficiency and the stability of the QLEDs, we have inserted an inorganic Al2O3 interfacial modification layer (IML) next to the electron transport layer (ETL) using atomic layer deposition (ALD). We conducted a comparative analysis of two different positions of Al2O3 IML inside the device, inserting IML before ETL and after ETL, to find an optimized structure for the efficient QLEDs. As a result, when Al2O3 IML was located after ETL, reduction of oxygen vacancy in the ZnO layer was occurred due to the reaction of O2 plasma reactant that used during the ALD process. It can have the effects of decreasing the exciton quenching phenomenon and balancing the charge injection. Therefore, improved device performances were observed, and the maximum luminance was 56 108 cd m−2 when 1 nm Al2O3 IML was deposited after ZnO ETL. These results suggest Al2O3 IML deposition would provide a useful way to improve the performance of QLEDs.

Ionic liquid-modified ZnO-based electron transport layer for inverted organic solar cells

In this work, a novel ionic liquid (IL) is demonstrated as an interface modification layer in photovoltaic devices to improve power conversion efficiency (PCE) in inverted organic solar cell (i-OSCs). As a result, the PTB7-Th:PC71BM-based devices using ZnO/IL as ETL layer exhibited over 15% PCE increment with enhanced short-circuit current density (Jsc) and fill factor (FF), compared with pure ZnO appliance in ETL. The ZnO layer modified with IL has a better electron extraction capability and lower work function, both of which contribute to better device performance.

Black phosphorus quantum dots as an effective perovskite interfacial modification layer for efficient low-temperature processed all-inorganic CsPbI2Br perovskite solar cells

Developing high-performance perovskite solar cells (PSCs) with all of the functional layers fabricated at low temperature (<180 °C) is highly desirable for the roll-to-roll processing of CsPbI2Br based PSCs. As for the all-inorganic perovskite, it is still a challenge to obtain void-free perovskite film especially prepared at this condition. Herein, we develop a facile approach to optimizing the morphology of low-temperature processed all-inorganic perovskite via using black phosphorus quantum dots (BPQDs) as an excellent interfacial modification material atop the perovskite layer for the first time. It is found that high-electron-mobility BPQDs can fill the voids between the grains of the perovskite film to provide more efficient pathways for electron extraction. Moreover, the BPQDs modification can effectively reduce the surface trap density of the perovskite layer, in addition to enhance the absorption of the PSC, thus suppressing nonradiative recombination losses. As a result, by incorporating BPQDs as the interfacial modification layer, our designed all-inorganic PSCs produce a maximum PCE of up to 12.2%. Furthermore, such highly efficient CsPbI2Br based PSC combined with the full low-temperature processing is rare, even outperforming most of previously reported CsPbI2Br based PSCs.

High performance top-emitting quantum dot light-emitting diodes with interfacial modification

In this paper, we report high performance top-emitting quantum dot light-emitting diodes (TE-QLEDs) with an interfacial modification layer. The specular metal bottom electrode was modified by an interfacial layer to improve the wettability of the aqueous solution on a metal electrode. By doing so, the potential barrier between the metal electrode and hole injection layer is decreased and the hole injection is enhanced. The capacitance analysis was used to understand the charge transfer process of the TE-QLEDs. The result showed that the indium tin oxide (ITO) interface layer is the best among NiOx, MoO3, and ITO. As a consequence, the red TE-QLEDs with an ITO interfacial modification layer show a maximum luminance and maximum external quantum efficiency of 18 880 cd/m2 and 11.8%, respectively. Our works indicate that the interfacial modification with metal oxides is an effective approach for high performance TE-QLEDs.

Enhancing the interface stability of Li1.3Al0.3Ti1.7(PO4)3 and lithium metal by amorphous Li1.5Al0.5Ge1.5(PO4)3 modification

Li1.3Al0.3Ti1.7(PO4)3 (LATP) has become the focus of research because of its high ionic conductivity, high oxidation voltage, and low air sensitivity. However, Ti4+ is easily reduced by Li metal. In this paper, amorphous Li1.5Al0.5Ge1.5(PO4)3 (a-LAGP) is introduced as an interface modification layer, because LAGP has the small electrochemical potential difference and Ge4+ is more difficult to be reduced by Li. Radio frequency sputtering (RF sputtering) is adopted to modify the a-LAGP thickness less than 100 nm. Compared with crystalline LAGP layer, a-LAGP has a better effect on improving the interface stability of LATP and Li. With the a-LAGP film, the Li/a-LAGP/LATP/a-LAGP/Li symmetrical cell is still stable after 100 cycles with the over potential changing from 1 V to 3 V. The probable mechanism of the good stability between a-LAGP and Li are discussed.

Carbon quantum dots interfacial modified graphene/silicon Schottky barrier solar cell

The two-dimensional thin film, as an effective interface modification layer to improve the power conversion efficiency (PCE) of graphene/silicon (Gr/Si) heterojunction solar cells has attracted extensive attention recently. However, the complicated manufacturing process and specialized equipment requirements impede its broad application. Herein, carbon quantum dots (CQDs) fabricated under the mild reaction condition was first time used to modify Gr/Si devices interface structure. The effects of CQDs size distributions and coating thickness on J-V characteristics and the energy band structure of Gr/CQDs/Si solar cells were systematically analyzed. The results indicate that the PCE of resulting Gr/CQDs/Si solar cells could reach 9.97% when the thickness and sizes of CQDs interlayer are ∼26 nm and 4–7 nm, without any chemical doping, which is 6.8-times PCE than that of virgin Gr/Si solar cells. The CQDs interlayer serves as both an electron blocking layer and hole transport layer to reduce the carrier recombination, leading to a lower reverse saturation current as well as a larger V OC then improved the device performance. The enhanced PCE shows that the CQDs species have the potential applications in a cost-effective photovoltaic device. • Novel Gr/CQDs/Si solar cell is demonstrated through a simple solution process. • The cleaner graphene transfer method based on cyclododecane species was achieved. • The enhanced PCE of 9.97% was achieved for ∼26 nm thickness GQDs with interlayer size of 4–7 nm. • The energy band structure of Gr/CQDs/Si solar cells were systematically analyzed.

Novel ultraviolet photodetector with ultrahigh photosensitivity employing SILAR-deposited ZnS film on MgZnO

Abstract A novel MgZnO/ZnS heterojunction-based ultraviolet (UV) photodetector (PD) with high performance is fabricated by a facile sol-gel process and a successive ionic layer adsorption and reaction (SILAR) method. ZnS is coated onto the MgZnO film as an interface modification layer, which overcomes the drawbacks of the pristine MgZnO photosensitive layer, such as lower carrier mobility and more traps in the material, and greatly enhances UV-light absorption. The type-II heterostructure constructed by work function differences near the interface facilitate the separation of photogenerated carriers. Compared with the MgZnO PD, the optimized heterojunction PD (MgZnO/ZnS-10) yields a dramatically decreased dark current (≈1 nA), a remarkable responsivity (900 A/W) and an ultrahigh photo-to-dark current ratio (up to 2.3 × 105) under 325 nm light illumination at 5 V bias. These results provide a cost-efficient means for improving the properties of MgZnO PDs, and show the advantages of MgZnO/ZnS heterojunction PDs in UV detection. This study demonstrates that rational construction of novel heterojunctions holds great potential for fabricating high-performance photodetectors.