Anode Interlayer Research Articles

Polypyrrole-Decorated Hybrid Anode Interlayer for Enhancing Efficiency and Stability of Non-Fullerene Solar Cells

Polypyrrole-Decorated Hybrid Anode Interlayer for Enhancing Efficiency and Stability of Non-Fullerene Solar Cells

Ligand‐Triggered MXene Quantum Dots with Tunable Work Function as Anode and Cathode Interlayers for Organic Solar Cells

The interfacial layers of organic optoelectronic devices generally suffer from the problems of difficulty in regulating the work function (WF) and low mobility, which are prone to mismatch of interfacial energy levels and loss of carrier transport energy. Herein, O‐terminated and NH2‐terminated Ti3C2Tx MXenes quantum dots (MQDs) are synthesized to develop efficient O‐MQD hole transfer layer (HTL) and E‐MQD electron transfer layer (ETL) for organic optoelectronic devices of organic solar cells (OSCs) and organic photodetectors (OPDs). It is found that the strong electronic coupling interaction between the surface terminations and matrices enables O‐MQD and E‐MQD with tunable WF and satisfactory conductivity. Consequently, in a binary D18:L8‐BO system, the power conversion efficiencies of the OSC device based on O‐MQD HTL and E‐MQD ETL are 18.62% and 18.15%, respectively. Moreover, the OPDs with O‐MQD HTL and E‐MQD ETL exhibit higher shot‐noise‐limited detectivity (Dshot*) of 1.24 × 1013 and 1.10 × 1013 Jones, respectively, compared to the devices using classic interlayers. These findings provide some insights into the design of advanced dual‐function interlayers for organic optoelectronic devices.

Fe3C/nanocarbon-Enabled Lithium Dendrite Mitigation in Lithium-Sulfur batteries.

Lithium dendrite-induced short circuits and material loss are two major obstacles to the commercialization of lithium-sulfur (Li-S) batteries. Here, a nanocarbon composite consisting of cotton-derived Fe3C-encapsulated multiwalled carbon nanotubes (Fe3C-MWCNTs) and graphene effectively traps polysulfides to suppress lithium dendrite growth is reported. Machine learning combined with molecular dynamics (MD) simulations unveils a new polysulfide-induced lithium dendrite formation mechanism: the migration of polysulfides away from the anode drags out lithium protrusions through localized lattice distortion of the lithium anode and traps lithium ions in the surrounding electrolyte, leading to lithium dendrite formation. The Li-S battery, constructed using the composite of cotton-derived Fe3C-MWCNTs and graphene that serves as both the sulfur host and the anode interlayer, exhibits exceptional cycling stability, impressive capacity retention, and effective mitigation of lithium dendrite formation. The findings offer valuable strategies to prevent lithium dendrite formation and enhance understanding of lithium dendrite growth in Li-S batteries.

18.9% Efficiency Binary Organic Solar Cells Enabled by Regulating the Intrinsic Properties of PEDOT:PSS

AbstractAnode interlayers play critical roles in organic solar cells, impacting the electrode's work function, energy level alignment, hole extraction, and electrode surfaces. However, the development of the commonly used anode interlayer PEDOT:PSS lags behind the rapid development of organic solar cells due to its low conductivity, acidity, and poor electron‐blocking capabilities. Herein, an innovative strategy is proposed to regulate the intrinsic properties of PEDOT:PSS by incorporating molybdenum‐containing semiconductors (MoO3, MoS2), which is validated using the state‐of‐the‐art active layer consisting of PM6:Y6 in conventional devices. The addition of molybdenum‐containing semiconductors alters the aggregation morphology of the PEDOT:PSS layer, increasing its conductivity and reducing its acidity. Furthermore, the hole extraction and electron‐blocking ability are improved by changing the work function of the anode with the influence of the deep energy level and by forming a trap energy level to capture electrons. Consequently, when the interlayer is employed, a champion power conversion efficiency of 17.1% in the PM6:Y6 devices and 18.9% in organic solar cells composed of PM6:L8‐BO is achieved. The results, which enhance the intrinsic properties of PEDOT:PSS with molybdenum‐containing semiconductors, offer valuable guidelines for engineering anode interlayers to fabricate highly efficient non‐fullerene organic solar cells.

Interface design for all-solid-state lithium batteries.

The operation of high-energy all-solid-state lithium-metal batteries at low stack pressure is challenging owing to the Li dendrite growth at the Li anodes and the high interfacial resistance at the cathodes1-4. Here we design a Mg16Bi84 interlayer at the Li/Li6PS5Cl interface to suppress the Li dendrite growth, and a F-rich interlayer on LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes to reduce the interfacial resistance. During Li plating-stripping cycles, Mg migrates from the Mg16Bi84 interlayer to the Li anode converting Mg16Bi84 into a multifunctional LiMgSx-Li3Bi-LiMg structure with the layers functioning as a solid electrolyte interphase, a porous Li3Bi sublayer and a solid binder (welding porous Li3Bi onto the Li anode), respectively. The Li3Bi sublayer with its high ionic/electronic conductivity ratio allows Li to deposit only on the Li anode surface and grow into the porous Li3Bi sublayer, which ameliorates pressure (stress) changes. The NMC811 with the F-rich interlayer converts into F-doped NMC811 cathodes owing to the electrochemical migration of the F anion into the NMC811 at a high potential of 4.3 V stabilizing the cathodes. The anode and cathode interlayer designs enable the NMC811/Li6PS5Cl/Li cell to achieve a capacity of 7.2 mAh cm-2 at 2.55 mA cm-2, and the LiNiO2/Li6PS5Cl/Li cell to achieve a capacity of 11.1 mAh cm-2 with a cell-level energy density of 310 Wh kg-1 at a low stack pressure of 2.5 MPa. The Mg16Bi84 anode interlayer and F-rich cathode interlayer provide a general solution for all-solid-state lithium-metal batteries to achieve high energy and fast charging capability at low stack pressure.

Design Strategies for Anodes and Interfaces Toward Practical Solid-State Li-Metal Batteries.

Solid-state Li-metal batteries (based on solid-state electrolytes) offer excellent safety and exhibit high potential to overcome the energy-density limitations of current Li-ion batteries, making them suitable candidates for the rapidly developing fields of electric vehicles and energy-storage systems. However, establishing close solid-solid contact is challenging, and Li-dendrite formation in solid-state electrolytes at high current densities causes fatal technical problems (due to high interfacial resistance and short-circuit failure). The Li metal/solid electrolyte interfacial properties significantly influence the kinetics of Li-metal batteries and short-circuit formation. This review discusses various strategies for introducing anode interlayers, from the perspective of reducing the interfacial resistance and preventing short-circuit formation. In addition, 3D anode structural-design strategies are discussed to alleviate the stress caused by volume changes during charging and discharging. This review highlights the importance of comprehensive anode/electrolyte interface control and anode design strategies that reduce the interfacial resistance, hinder short-circuit formation, and facilitate stress relief for developing Li-metal batteries with commercial-level performance.

Mixed‐Addenda Dawson‐Type Polyoxometalates as High‐Performance Anode Interlayer Materials for Efficient Organic Optoelectronic Devices

AbstractElectrode interlayer plays a pivotal role in the performance enhancement of optoelectronic devices. At present, poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and molybdenum oxide are the two most popular anode interlayer (AIL) materials in organic optoelectronic devices, but both of them have obvious drawbacks in practical use. Owing to the lack of suitable semiconductor with suitable energy level, the development of AIL materials as alternatives to PEDOT:PSS and MoO3 remains a challenge. Herein, a series of Dawson‐type polyoxometalates (POMs) is synthesized with tunable chemical compositions and photoelectronic properties to develop efficient AILs for organic optoelectronic devices of organic light‐emitting diode (OLED) and organic solar cell (OSC). The POM films exhibit a high work function, excellent conductivity, good optical transmittance, and smooth surface, endowing the POM AILs with outstanding hole injection/collection abilities. The high performance of Dawson‐type POMs in hole injection/collection ensures an efficient hole transfer from the organic layer to the anode, depressing the charge recombination in the optoelectronic devices. The OSCs modified by POM4 exhibit 17.8% and 16.1% power conversion efficiencies with an active area of 0.04 and 1.00 cm2, respectively. The OLEDs with POM3 and POM4 exhibit remarkably superior luminous efficiency to the PEDOT:PSS device, along with a significantly reduced turn‐on voltage from 3.8 to 2.8 V.

P—π Conjugated Polyelectrolytes Toward Universal Electrode Interlayer Materials for Diverse Optoelectronic Devices

AbstractThe development of universal interlayer materials for diverse optoelectronic devices not only decreases the costs in both laboratory research and industrialized production, but also improves the uniformity of different devices so as to facilitate device integration. However, using one material to fabricate diverse devices remains a great challenge. Herein, p‐π conjugation is utilize to replace the commonly used π–π conjugation to develop an unprecedented anode interlayer (AIL) material PCP‐S that can be universally used in diverse optoelectronic devices, including organic light‐emitting diode (OLED), organic solar cell (OSC), and perovskite solar cell (PSC). The unique solubility and the easy adjustment of optoelectronic properties are keys to realize the multiple uses of PCP‐S. First, OSC based on the polyoxometalate (POM)‐doped PCP‐S exhibits a high power conversion efficiency (PCE) of 17.1%, representing the highest efficiency for OSCs using a solution‐processed pH‐neutral AIL. Second, PSC with PCP‐S shows a PCE of 20.1%, which is superior to the device with poly(triaryl amine) (PTAA). Third, OLED possesses a significantly reduced turn‐on voltage from 3.8 to 2.8 V by incorporating the PCP‐S AIL. To the best of the authors’ knowledge, this is the first example of a universal AIL material to realize multiple applications.

Anode interfacial modification for non‐fullerene polymer solar cells: Recent advances and prospects

AbstractRecently, the power conversion efficiency (PCE) of single‐junction non‐fullerene polymer solar cells (NF‐PSCs) has surpassed 19% due to the fast development of novel donor polymers, NF‐acceptors, device engineering, and interlayer materials. The anode interlayer (AIL) plays a vital role in improving the efficiency and stability of PSCs. The challenges and opportunities in this research area encourage researchers to pursue great innovation in developing new materials and strategies for highly efficient NF‐PSCs. This review summarizes the recent development of AIL materials and their modification strategies in single‐junction NF‐PSCs. Firstly, a brief introduction, key functions, basic requirements, and peculiar features of AILs when employed in NF‐PSCs are discussed. Then, the impact of AIL materials (including organic, inorganic, and hybrid materials) on the PCE and the stability of NF‐PSCs are described. Afterward, the fabrication of large‐area devices and related issues are highlighted. The summary and the future challenges regarding efficient AIL are summarized in the last section of this review.image

Fluorinated Interlayer Modulation of NiOx-Based Inverted Perovskite Solar Cells.

p-Type inorganic nickel oxide (NiOx) exhibits high transparency, tunable-optoelectronic properties, and a work function (WF) that is potentially suitable for hole extraction in inverted perovskite solar cells (PSCs). However, NiOx films possess surface defects that lead to high interfacial recombination and an energy offset with the ionization potential of the perovskite. Herein, we show that fluorinated 3-(2,3,4,5,6-pentafluorophenyl)propan-1-aminium iodide (FPAI) can be used to modify the electronic properties of the NiOx anode interlayer. The FPAI modification led to good perovskite crystal growth and films with reduced surface defects. The FPAI modification also increased the WF of NiOx and improved charge extraction. These improvements led to an increased Voc value compared with control devices without FPAI modification, 1.05 V versus 1.00 V, and a higher short-circuit current and larger fill factor. As a result, the best PSCs with FPAI-modified NiOx had a power conversion efficiency of 19.3%. Finally, the PSCs with the FPAI-modified NiOx layer were found to have improved stability.

{Mo132} as Both Anode and Cathode Interlayers in Organic Optoelectronic Devices by Tuning Counter Cations

{Mo132} as Both Anode and Cathode Interlayers in Organic Optoelectronic Devices by Tuning Counter Cations

Water‐Soluble Organic Dyes as Efficient Anode Interlayer Materials for PEDOT:PSS‐Free Inverted Bulk Heterojunction Solar Cells

Solution‐processed inverted organic solar cells (OSCs) generally use poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate (PEDOT:PSS) as hole selective anode interlayer (AIL). However, the acidic nature of PEDOT:PSS considerably accelerates the degradation dynamics of OSCs, which shortens the durability of these low‐cost photovoltaic devices. Small organic molecules are attracting growing interest as alternative AIL materials, but their solubility limited to toxic organic solvents hinders the production of environmentally friendly OSCs. Herein, the first inverted OSCs employing non‐PEDOT:PSS solution‐processed top small organic molecule AILs deposited from aqueous solution are reported. The investigated water‐soluble spirobifluorene (SBF) derivatives 1 and 2 show hole mobility (≈4 × 10−3 cm2 V−1 S−1) higher than PEDOT:PSS. Because of their nonacidic nature, the interlayers formed with derivatives 1 or 2 considerably delay the degradation of the top metal electrode compared to OSCs employing PEDOT:PSS interlayers. The PEDOT:PSS‐free OSC devices with inverted configuration with the water‐soluble SBF derivatives as AIL produce power conversion efficiencies above 5% with PTB7‐Th:ITIC active layers and above 8% with PBDB‐T‐2Cl:Y6 active layers, respectively, with an enhancement up to 28% compared to OSCs employing PEDOT:PSS. These results correspond to the highest reported values for PEDOT:PSS‐free small‐molecule inverted OSCs deposited from an aqueous solution.

In-situ self-organized anode interlayer enables organic solar cells with simultaneously simplified processing and greatly improved efficiency to 17.8%

Highly efficient organic solar cells (OSCs) are often obtained with a multilayer structure, in which active layer is sandwiched between anode and cathode interlayer. Here we present a simple strategy to simultaneously obtain anode interlayer and boost performances of OSCs by directly adding a tiny small molecule [2-(9H-carbazol-9-yl)ethyl] phosphonic acid (2PACz) into the active layer. It is found that 2PACz with high surface energy prefers to self-organize at the bottom of PM6:Y6-BO bulk heterojunction (BHJ) blend and in-situ form anode interlayer during the film formation. Encouragingly, green solvent o-xylene processed OSCs with substantial improvement of photovoltaic performances are observed in self-organized 2PACz device with best power conversion efficiency (PCE) reaching 17.8%, notably higher than that of control device based on independently spin-coated 2PACz with a PCE of 16.8%. In-depth studies indicate the in-situ self-organized 2PACz underneath BHJ is beneficial to enhance build-in potential, suppress surface trap-assisted recombination, and induce ordered molecule stacking. Moreover, this self-organization method is implanted in a large-area OSC with 1 cm2 device area and an outstanding PCE of 15.8% is achieved. These results above highlight the great potential of in-situ self-organization method in simplifying device processing as well as improving efficiency, which make it an ideal strategy for large-area OSCs manufacture.

High-performance hole transport layer based on WS2 doped PEDOT:PSS for organic solar cells

In this work, we developed WS2 nanosheets (WS2 NS) doped into PEDOT:PSS (PEDOT:PSS/WS2 NS) as an efficient hole transport layer (HTL) for organic solar cells (OSCs). WS2 NS is obtained by a simple and cost-effective liquid-phase exfoliation (LPE) method. The results show that the PEDOT:PSS:WS2 NS anode interlayer has higher work function, reduced roughness and improved hole mobility. The devices based on PEDOT:PSS:WS2 NS interlayer show enhanced extraction and transportation of holes and improved fill factor and short-circuit current density. Based on PM6:Y6, the power conversion efficiency (PCE) increased from 14.35% to 15.67% after WS2 NS doping.

Exploring Inorganic Hole Collection Materials from Mixed‐Metal Dawson‐Type Polyoxometalates for Efficient Organic Photovoltaic Devices

Interfacial layer materials play an important role in performance enhancement of organic solar cells (OSCs). Herein, the utilization of mixed‐metal Dawson‐type polyoxometalates, namely P2Mo3W15O62 (POM‐1) and P2Mo9W9O62 (POM‐2), as anode interlayer (AIL) materials, for efficiently collecting holes to boost the photovoltaic efficiency of OSCs, is explored. The increase in molybdenum substitution in the mixed‐metal POMs can lower the conduction band level and increase the reduction potential. Meanwhile, the high work function of POMs helps to remove the energy barrier in the hole collection, which solves the serious problem of Voc loss in OSCs. As a result, OSCs modified by POM‐2 can exhibit superior photovoltaic performance with power conversion efficiency of 14.8%. The results of Mott−Schottky analysis, current density−light intensity dependence, and excitons dissociation probability indicate the efficient hole collection and the depressed charge recombination in the POM‐2‐based OSC device. By means of fabricating OSCs, the effect of the two POM‐based AILs on various photoactive layers is also investigated, and POM‐2 exhibits excellent hole collection capability. Moreover, the advantages of low‐cost and solution‐processable conduct make POM‐2 a promising candidate as the AIL material for future mass production of OSCs.

Ultrafast Synthesis of I-Rich Lithium Argyrodite Glass-Ceramic Electrolyte with High Ionic Conductivity.

Lithium argyrodites are one of the most promising sulfide electrolytes due to their high ionic conductivity and ductile feature. Among them, Li6 PS5 I (LPSI) exhibits better stability against Li metal but a rather low ionic conductivity (only ≈10-6 S cm-1 ) because of the absence of S2- /I- disorder. Herein, argyrodite Li6- x PS5- x I1+ x glass-ceramic electrolytes with high iodine content are synthesized using ultimate-energy mechanical alloying method. S2- /I- disorder is successfully introduced into the system by doping LiI during this one-pot process. Determined by 6 Li magic angle spinning nuclear magnetic resonance and ab initio molecular dynamics simulations, the introduction of iodine promotes Li+ inter-cage jumps, leading to an enhanced long-range Li+ conducting. The Li5.6 PS4.6 I1.4 glass-ceramic electrolyte (LPSI1.4 -gc) possesses high ionic conductivity (2.04 mS cm-1 ) and excellent stability against Li metal. The Li symmetric cell with the LPSI1.4 -gc electrolyte demonstrates ultralong cycling stability over 3200 h at 0.2mA cm-2 . LiCoO2 /Li6 PS5 Cl/Li all-solid-state battery applying LPSI1.4 -gc as the anode interlayer also presents prominent cycling and rate performance. This work provides a novel type of electrolyte with high ionic conductivity and stability against Li metal.

Study on the effect of tin and antimony oxide interlayer on the performance of titanium-based manganese dioxide anode

Tin-antimony interlayer and manganese dioxide active catalytic coating were prepared on titanium plate by coating and thermal decomposition. The load of interlayer and calcination temperature were selected as the influencing factors for univariate experiment. The seen morphology of the electrode was explored by SEM. The electrocatalytic performance and oxygen evolution mechanism were analyzed by testing the cyclic voltammetry curve, oxygen evolution polarization curve and AC impedance graph, the optimal preparation conditions of the Ti-Mno2 anode interlayer were obtained.

Localization of electrons within interlayer stabilizes NASICON-type solid-state electrolyte

Although Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte has the advantages of high ionic conductivity, low cost, and satisfying air stability, it is thermodynamically unstable with lithium metal, which could reduce the Ti4+ to Ti3+ and form a highly resistive interface, leading to the fast degradation of battery performance. Herein, through an in-depth study on the degradation mechanism of LATP by delocalized π electrons in succinonitrile (SN), we propose a novel plastic composite interlayer (PCI) based on succinonitrile and polyacrylonitrile, which can not only realize a rapid and uniform transmission of lithium ions but also localize π electrons, inhibit the continuous deterioration of LATP. Compared with previous battery tests at elevated temperatures or by adding liquid components, the PCI-based Li|Li symmetric cell has achieved a cyclability for more than 300 h at room temperature. Moreover, the discharge capacity of the all-solid-state battery based on PCI still retains 87.9% after 170 cycles at 0.1C, which is in sharp contrast to the 38.6% capacity retention after 50 cycles of LFP/SN/LATP/SN/Li battery. These results show that PCI, as an effective anode interlayer, paves a way for high-performance solid-state batteries based on NASICON-type electrolytes.

Design of NiOx/Carbon Heterostructure Interlayer to Improve Hole Extraction Efficiency of Inverted Perovskite Solar Cells

AbstractAn efficient hole transport layer (HTL) with desirable charge separation and hole extraction efficiency is crucial for inverted perovskite solar cells. However, the interfacial trap recombination loss and mismatched band alignment limit the actual performance of device, especially the open‐circuit voltage (VOC). To address this issue, a unique NiOx/carbon heterostructure is designed as efficient anode interlayer for optimizing the interfacial charge transport dynamics between HTL and perovskite. Such a buffer interlayer can significantly contribute to the improved hole conductivity and hole extraction efficiency at HTL/perovskite interface. Moreover, the more favorable gradient energy level alignment can be formed to increase the interfacial electric field, inhibit the nonradiative recombination, and minimize the VOC loss. Therefore, the champion device achieves 19.51% efficiency with high VOC of 1.13 V, close to the highest power conversion efficiencies of MAPbI3 device. This work suggests that interface design can be an alternative approach to fabricate efficient inverted NiO‐based devices.

Tin(II) thiocyanate Sn(SCN)2 as an ultrathin anode interlayer in organic photovoltaics

We report the application of a coordination polymer semiconductor, tin(II) thiocyanate [Sn(SCN)2], as an ultrathin anode interlayer in organic photovoltaics (OPVs). Sub-10 nm layers of Sn(SCN)2 with high smoothness and excellent transparency having an optical bandgap of 3.9 eV were deposited from an alcohol-based solution at room temperature without post-deposition annealing. Inserting Sn(SCN)2 as an anode interlayer in polymer:fullerene OPVs drastically reduces the recombination loss due to the exciton-blocking energy levels of Sn(SCN)2. At the optimum thickness of 7 nm, an average power conversion efficiency (PCE) of 7.6% and a maximum of 8.1% were obtained. The simple processability using common solvents gives Sn(SCN)2 a distinct advantage over the more well-known copper(I) thiocyanate (CuSCN). The electronic and optical properties of Sn(SCN)2 make it interesting for applications in large-area electronic devices.