Electron Transport Layer Research Articles

Tungsten-Doped ZnO as an Electron Transport Layer for Perovskite Solar Cells: Enhancing Efficiency and Stability.

This study delves into enhancing the efficiency and stability of perovskite solar cells (PSCs) by optimizing the surface morphologies and optoelectronic properties of the electron transport layer (ETL) using tungsten (W) doping in zinc oxide (ZnO). Through a unique green synthesis process and spin-coating technique, W-doped ZnO films were prepared, exhibiting improved electrical conductivity and reduced interface defects between the ETL and perovskite layers, thus facilitating efficient electron transfer at the interface. High-quality PSCs with superior ETL demonstrated a substantial 30% increase in power conversion efficiency (PCE) compared to those employing pristine ZnO ETL. These solar cells retained over 70% of their initial PCE after 4000 h of moisture exposure, surpassing reference PSCs by 50% PCE over this period. Advanced numerical multiphysics solvers, employing finite-difference time-domain (FDTD) and finite element method (FEM) techniques, were utilized to elucidate the underlying optoelectrical characteristics of the PSCs, with simulated results corroborating experimental findings. The study concludes with a thorough discussion on charge transport and recombination mechanisms, providing insights into the enhanced performance and stability achieved through W-doped ZnO ETL optimization.

Post‐Treated Polycrystalline SnO2 in Perovskite Solar Cells for High Efficiency and Quasi‐Steady‐State‐IV Stability

AbstractThe prominent chemical bath deposition (CBD) method leverages tin dioxide (SnO2) as an electron transport layer (ETL) in perovskite solar cells (PSCs), achieving exceptional efficiency. The deposition of SnO2, however, can lead to the formation of oxygen vacancies and surface defects, which subsequently contribute to performance challenges such as hysteresis and instability under light‐soaking conditions. To alleviate these issues, it is crucial to address heterointerface defects and ensure the uniform coverage of SnO2 on fluorine‐doped tin oxide substrates. Herein, the efficacy of tin(IV) chloride (SnCl4) post‐treatment in enhancing the properties of the SnO2‐ETL and the performances of PSCs are presented. The treatment with SnCl4 not only removes undesired agglomerated SnO2 nanoparticles from the surface of CBD SnO2 but also improves its crystallinity through a recrystallization process. This leads to an optimized interface between the SnO2‐ETL and perovskite, effectively minimizing defects while promoting efficient electron transport. The resultant PSCs demonstrate improved performance, achieving an efficiency of 25.56% (certified with 24.92%), while retaining 95.84% of the initial PCE under ambient storage conditions. Additionally, PSCs treated with SnCl4 endure prolonged light‐soaking tests, particularly when subjected to quasi‐steady‐state‐IV measurements. This highlights the potential of SnCl4 treatment as a promising strategy for advancing PSC technology.

SCAPS 1D based study of hole and electron transfer layers to improve MoS2–ZrS2 solar cell efficiency

In the realm of photovoltaic applications, scientists and technocrats are striving to maximize the solar cell input photon energy conversion to electricity. However, achieving optimal cell efficiency requires significant time and energy investment for each variation and optimization. To overcome this issue authors simulated and studied the fabricated cell for optimizing conditions, which can save time and efforts for the relatively better outcomes. The family of transition metal chalcogenides holds promise as a material that yield improved outcomes in optoelectronic applications, particularly in photovoltaics. These materials are employed in experimental investigations aimed at enhancing solar cell parameters, resulting in the development of the FTO/ZnO/ZrS2/MoS2/CuO/Au composite cell. Numerical simulations utilizing SCAPS-1D software is conducted, focusing on the significance of CuO as a hole transport layer (HTL), and ZnO as an electron transport layer (ETL). The investigation examines into the impact of various factors, including thickness, bandgap, and carrier densities for both HTL and ETL, on fundamental solar cell parameters. The study indicates that device parameters are influenced by factors such as recombination rate, photogenerated current, charge carrier length, and built-in-voltage. Optimized parameters for HTL, including thickness, bandgap, and carrier concentration, are determined to be 0⋅35 μm, 1⋅2 eV, and 1⋅0 × 1020 cm–3, respectively. For ETL, the optimized parameters are found to be 0⋅05 μm, 3⋅1 eV, and 1⋅0 × 1018 cm–3, respectively. With these optimized parameters, the efficiency of the solar cell reached 20⋅64%, accompanied by open circuit voltage, short circuit current density, and fill factor values of 0.836 V, 36.021 mA⋅cm–2, and 68⋅54%, respectively. The simulated results indicate that addition of two extra layers and the use of efficient binary materials in heterojunction formation can effectively enhance device parameters, offering advantages such as low-cost and large-scale fabrication.

Analysis and design of 25.3% efficient Sb2Se3 solar cells by numerical simulation

Sb2Se3 has a high absorption coefficient of 105 cm−1 in the visible light range, which is an excellent absorber layer material. Currently, a better band alignment between conventional CdS and Sb2Se3 has led to the widespread adoption of CdS as the electron transport layer (ETL) in Sb2Se3 solar cells. However, CdS is toxic, necessitating the exploration of alternative ETL materials that are eco-friendly and possess an appropriate energy band with Sb2Se3. In this study, we endeavor to pioneer an all-inorganic, green solar cell structure of Au/MoS2/Sb2Se3/WS2/ITO by employing MoS2 as the hole transport layer (HTL) and WS2 as the ETL. We primarily optimized Sb2Se3 thickness and its hole doping concentration (NA) by SCAPS-1D numerical simulation. Based on the analysis of built-in electric field and carrier recombination rate along Sb2Se3, the optimal thickness and NA ranges of Sb2Se3 are determined, which are 0.9–1.1 μm and 1016-1018 cm−3 respectively. Through a series of optimization, the structure achieves the highest power conversion efficiency (PCE) of about 25.3 % in the current simulation of Sb2Se3 solar cells. After comparing the novel WS2 ETL with the conventional CdS ETL, we find that WS2 has a larger built-in potential (Vbi) and charge recombination resistance (Rrec). In addition, from the analysis of energy band structure, the spike-like band at Sb2Se3/WS2 interface can effectively inhibit the carrier recombination, which makes the device obtain a larger open circuit voltage (VOC) of 0.69 V. This study can provide theoretical reference for the development of non-toxic and efficient Sb2Se3 solar cells.

Rational tuning of SnO2 electron transport layer grown by atomic layer deposition for performance improvement of perovskite solar cells

The electron transport layer (ETL) of a perovskite solar cell (PSC) plays a pivotal role in determining cell performance. In this work, an atomic layer deposition (ALD) technique was employed to grow high-quality SnO2 thin films, and those ALD-grown SnO2 films were used as ETLs of PSCs. The properties of films and the performance of PSCs were closely examined depending on the SnO2 growth conditions. The SnO2 films grown at higher temperatures showed a very small surface roughness (≤0.6 nm) though grown faster. The relative oxygen content of the film was inclined to decrease with increasing the growth temperature. Consequently, the carrier concentration and the Fermi level of the film became higher at elevated temperatures. PSCs with ALD-grown SnO2 ETLs also revealed a clear correlation between cell performance and the film growth temperature. The results of this work may offer practical guidelines for enhancing the performace of a PSC that employs a metal oxide as an ETL.

An investigation on the impact of temperature variation over the performance of formamidinium tin iodide perovskite solar cell using SCAPS simulation

The primary goals of this project are to analyze the structure and assess the photovoltaic performance of n-i-p structured formamidinium tin iodide (FASnI3) perovskite solar cells at different operating temperatures to inspect the impact of operating temperature on device performance using a Solar Cell Capacitance Simulator (SCAPS). The simulated device structure is Au/spiro-OMeTAD/P3HT/FASnI3/PCBM/TiO2/FTO, whereas spiro-OMeTAD and TiO2 serve as the hole transport layer and electron transport layer, respectively. SCAPS simulation has been performed at 200, 300, 400, 500, and 600 K operating temperatures, and corresponding current density vs voltage (J–V) characteristics have been studied in addition to the photovoltaic metrics, such as open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF), and power conversion efficiency (PCE). The thickness fluctuation and doping concentration variation of the absorber layer and the electron affinity variation and thickness variation of the Hole Transport Layer (HTL) and Electron Transport Layer (ETL) under temperature variation were also examined analytically. It has been found that there is an inverse relationship between temperature and power conversion efficiency (PCE). The extended thickness of the absorber layer enhances the PCE and JSC. Temperature variations in the thickness of the ETL and HTL have a minimal effect on the PCE and JSC of the device. At standard room temperature (300 K operating temperature), the solar cell parameters are found to be a short-circuit current density (JSC) of 17.93 mA/cm2, open-circuit voltage (VOC) of 1.06 V, fill factor (FF) of 67.46% and power conversion efficiency (PCE) of 17.93%.

Investigation of impact of kesterites as hole transport layer on (FA)2BiCuI6 based ecofriendly double perovskite solar cell to obtain optimized PCE above 25%

This paper presents a detailed study of double perovskite (FA)2BiCuI6 based perovskite solar cells(PSC) using different kesterites as hole transport layers (HTL) and titanium-based electron transport layers (ETL). The designed double perovskite PSC utilized TiO2 as an ETL, different kesterite materials (CZTSe, CFTS, CBTS, CMTS, CNTS and CZTS) as the HTL, double perovskite material (FA)2BiCuI6 as the perovskite absorption layer (PAL), Indium tin oxide (ITO) as top electrode and Au as an anode. The different parameters of architecture (ITO/TiO2/(FA)2BiCuI6/HTL/Au) is improved via the SCAPS-1D simulator by first optimizing thickness and then the defect density of PAL. Energy band matching of the different layers with (FA)2BiCuI6 is thoroughly investigated in order to understand its operation. AM 1.5G illumination is used as input light source. To obtain optimum performance of (FA)2BiCuI6 based PSC the effects of optical thickness, defect density, temperature, series resistance, and shunt resistance are monitored. Among all the kesterites, CNTS based PSC performed extraordinarily well with PCE of 26.09 %. JSC 22.64 mA/cm2, VOC 1.38 V, FF 83.33 %, and the variables influencing solar cell performance are clarified by simulations. The findings presented in this work will aid researchers in the production of ecofriendly solar cells with great efficiency.

Performance optimization of lead-free potassium germanium halide based perovskite solar cells: A numerical study

Conventional lead-halide perovskite solar cells (PSCs) have great potential as top contenders for commercial utilization due to their impressive performance. Nevertheless, the stability issues and undue toxicity have limited their widespread use. Consequently, lead-free germanium-based PSCs have materialized as potential substitutes due to their high working efficiency and exceptional sustainability. The current study has examined various configurations of non-toxic inorganic potassium germanium trichloride (KGeCl3) based PSC structure by using different Hole Transport Layers (HTL) and Electron Transport Layers (ETLs) respectively. This work proposes an efficient Ge-based PSC (structure; FTO/MoO3/KGeCl3/WS2/Au), which has been optimized theoretically using SCAPS-1D. The influence of the material parameters, such as the thickness of the absorber layer (nm), donor density (Nd), acceptor density (Na), absorber defect density(Nt), interface layer defect density (IL1& IL2), series resistance (Rs) and shunt resistance (Rsh), and working temperature (K), has been optimized. The open circuit voltage (Voc), current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) of KGeCl3-based PSC have all been commendably optimized. The results indicated WS2 as the most effective ETL for KGeCl3 with MoO3 as an HTL, yielding notable cell performance with Voc of 0.88 V, Jsc of 41.45 mA/cm2, FF of 81.76 %, and PCE of 29.83 %. The outcomes of this simulation study suggest the utilization of KGeCl3 as the absorber layer, in conjunction with WS2 and MoO3 as advanced ETL and HTL layers, which pays the way for continued development and optimization of Ge-based PSCs for potential applications.

Over 19% Efficient Inverted Organic Photovoltaics Featuring a Molecularly Doped Metal Oxide Electron-Transporting Layer.

Molecular doping is commonly utilized to tune the charge transport properties of organic semiconductors. However, applying this technique to electrically dope inorganic materials like metal oxide semiconductors is challenging due to the limited availability of molecules with suitable energy levels and processing characteristics. Herein, n-type doping of zinc oxide (ZnO) films is demonstrated using 1,3-dimethylimidazolium-2-carboxylate (CO2-DMI), a thermally activated organic n-type dopant. Adding CO2-DMI into the ZnO precursor solution and processing it atop a predeposited indium oxide (InOx) layer yield InOx/n-ZnO heterojunctions with increased electron field-effect mobility of 32.6 cm2 V-1 s-1 compared to 18.5 cm2 V-1 s-1 for the pristine InOx/ZnO bilayer. The improved electron transport originates from the ZnO's enhanced crystallinity, reduced hydroxyl concentrations, and fewer oxygen vacancy groups upon doping. Applying the optimally doped InOx/n-ZnO heterojunctions as the electron-transporting layers (ETLs) in organic photovoltaics (OPVs) yields cells with improved power conversion efficiency of 19.06%, up from 18.3% for devices with pristine ZnO, and 18.2% for devices featuring the undoped InOx/ZnO ETL. It is shown that the all-around improved OPV performance originates from synergistic effects associated with CO2-DMI doping of the thermally grown ZnO, highlighting its potential as an electronic dopant for ZnO and potentially other metal oxides.

Multifunctional organic salts synergize interfacial passivation for efficient PSCs

Fully inorganic metal halide perovskite solar cells (PSCs) exhibit high efficiency and excellent thermal stability. However, the presence of surface traps caused by oxygen vacancies in the electron transport layer leads to significant non-radiative charge recombination, which limits both the short-circuit current density (JSC) and photoelectric conversion efficiency (PCE). In this study, we propose a dual-purpose strategy by incorporating the multifunctional organic salt dopamine hydrochloride (DACl) as an additive into the electron transport layer. Firstly, DACl acts as a Lewis base when added to TiO2 films, facilitating improvements in electron transport properties and resulting in higher photovoltaic quality of subsequently deposited perovskite layers. This enhancement significantly improves overall photovoltaic performance. Secondly, DACl's electron-rich aromatic structure and -NH2 functional group can anchor undercoordinated Pb2+ ions and passivate defects within the perovskite film. Additionally, its -OH functional group and charged ion Cl- play crucial roles in improving perovskite grain size and crystallinity. As a result of these modifications, cell efficiency increased ∼35 %, from 9.37 % to 12.70 %, while short-circuit current density increased from 15.44 mA cm−2 to 17.80 mA cm−2 at an illumination intensity of 100 mW cm−2. These findings suggest that introducing DACl into the ETL layer is a promising approach for achieving efficient and stable PSCs.

Modified SnO2 Electron Transport Layer by One‐Step Doping with Histidine in Perovskite Solar Cells

Tin dioxide (SnO2), one of the best electron transport layer materials for perovskite solar cells (PSCs), has high electrical conductivity and low photocatalytic activity. However, the defects in its inside and surface result in nonradiative recombination at the SnO2/perovskite interface. Complex and time‐consuming passivation methods are not conducive to the commercialization of PSCs, and simple passivation strategies should be used to improve the photovoltaic performance of the devices. Herein, a facile and efficient method is proposed to simultaneously passivate the inside and surface defects by adding histidine (HIS) to SnO2 colloidal solution. This one‐step doping strategy also modulates carrier dynamics at the SnO2/perovskite interface. HIS reduces suspended hydroxyl groups, oxygen vacancies, and uncoordinated Sn4+ defects on the surface of SnO2, as well as uncoordinated Pb2+ and halogen vacancy defects at the buried interface of perovskite. Surprisingly, HIS can prevent perovskite from decomposition to form PbI2, which further decomposes to photoactive metallic Pb0 and I, causing ion migration in PSC. As a result, the PSC efficiency has significantly improved 23.11% after HIS doping. The efficiency of unencapsulated device with HIS is 94% of the primary efficiency after storage in relative humidity = 70 ± 5% for 1000 h.

Temperature effects on Cadmium Selenide semiconductor-sensitized solar cells with SnO2 deposition as electron transport layer

Temperature effects on Cadmium Selenide semiconductor-sensitized solar cells with SnO2 deposition as electron transport layer

An Overview of Electron Transport Layer Materials and Structures for Efficient Organic Photovoltaic Cells

The electron transport layer (ETL) has gained significant attention recently for its essential role in facilitating charge extraction, transportation, and reducing recombination in photovoltaic cells. Organic photovoltaics (OPVs) with ETLs have achieved remarkable efficiencies exceeding 19%, and indoor OPVs have reached a peak efficiency of 29.4% under 3000 LX illumination. Despite these accomplishments, the difficulties in choosing appropriate ETLs for contact alignment have constrained device performance. This review comprehensively overviews the latest advancements in ETL materials used in conventional and inverted OPVs. Additionally, it investigates the evolution of dopant materials, emphasizing the need for improved electron mobility, energy level alignment, and surface passivation treatment of the buffer layer and absorber layers in OPVs. Continual studies of transport materials and the potential utilization of doping or multilayer ETLs are suggested as inevitable research toward achieving higher power conversion efficiency and stability in OPV technology. Additionally, identifying optimal ETL materials capable of synergistic interactions remains crucial for sustained progress in renewable energy technology.

Effect of Al Dope with ZnO Electron Transport Layer in Perovskite Solar Cells Using SCAPs 1-D Simulation

Perovskite solar cells have shown exceptional performance and significant advancements in solar cell efficiency. For perovskite solar cells to conduct electrons and generate current, one of the key components is the substance known as the electron transport layer (ETL). Using the SCAPS 1D modelling program, ZnO: Al was used in this instance as the ETL material in a perovskite solar cell. Because of its interaction with the perovskite material, the ZnO: Al ETL demonstrated high cell efficiency. The performance of the ZnO: Al-doped-based solar cell achieved a PCE as high as 23.5%. In the meanwhile, the greatest cell performance in terms of enhancing the charge transport mechanism and raising cell efficiency was shown by perovskite solar cells doping the ETL with Al and having the right layer thickness. Thus, throughout the manufacturing process, the parameters used in this study may serve as a guide.

The Role of Optimal Electron Transfer Layers for Highly Efficient Perovskite Solar Cells-A Systematic Review.

Perovskite solar cells (PSCs), which are constructed using organic-inorganic combination resources, represent an upcoming technology that offers a competitor to silicon-based solar cells. Electron transport materials (ETMs), which are essential to PSCs, are attracting a lot of interest. In this section, we begin by discussing the development of the PSC framework, which would form the foundation for the requirements of the ETM. Because of their exceptional electronic characteristics and low manufacturing costs, perovskite solar cells (PSCs) have emerged as a promising proposal for future generations of thin-film solar energy. However, PSCs with a compact layer (CL) exhibit subpar long-term reliability and efficacy. The quality of the substrate beneath a layer of perovskite has a major impact on how quickly it grows. Therefore, there has been interest in substrate modification using electron transfer layers to create very stable and efficient PSCs. This paper examines the systemic alteration of electron transport layers (ETLs) based on electron transfer layers that are employed in PSCs. Also covered are the functions of ETLs in the creation of reliable and efficient PSCs. Achieving larger-sized particles, greater crystallization, and a more homogenous morphology within perovskite films, all of which are correlated with a more stable PSC performance, will be guided by this review when they are developed further. To increase PSCs' sustainability and enable them to produce clean energy at levels previously unheard of, the difficulties and potential paths for future research with compact ETLs are also discussed.

Improving the power conversion efficiency of RbPbBr3 absorber based solar cells through the variation of efficient hole transport layers

Novel rubidium-lead-bromide (RbPbBr3) hybrid perovskite solar cells (HPSCs) are gaining attention from researchers because of their exceptional semiconductor qualities. Researchers have been examining RbPbBr3-based single junction photovoltaic cells in a number of configurations, including two different hole transport layers (HTL) made of V2O5 and MoTe2 and an electron transport layer (ETL) made of CdS. We investigated elements including band alignment, defect density, layer thickness, doping concentration, interface defect density, carrier concentration, generation, recombination, open circuit voltage (VOC), short circuit current (JSC), fill factor (FF), and power conversion efficiency (PCE) through extensive numerical analysis using SCAPS-1D simulation software. According to the research, the V2O5 HTL design, with a VOC of 1.1433 V, a JSC of 34.3969 mAcm−2, and an FF of 86.63 %, attained the maximum PCE at 34.06 %. By contrast, the MoTe2 HTL configuration's PCE was 31.66 %, with a VOC of 1.0388 V, a JSC of 34.4977 mAcm−2, and an FF of 88.35 %. These results provide insightful information and a workable strategy for creating RbPbBr3-based, reasonably priced thin-film solar cells.

Progressive quenching of luminescence from quantum dot thin films in proximity with ZnMgO in unencapsulated stacks

ZnMgO nanoparticles (NPs) are being increasingly used as the electron transport layer (ETL) in state-of-the-art quantum-dot light-emitting devices (QLEDs) instead of ZnO. However, the impact of ZnMgO on the luminescence properties of quantum dots (QDs) is much less understood. Here, we compare ZnMgO and ZnO NPs for their quenching effect on Cd-based QDs photoluminescence (PL), immediately and over time. Time-resolved photoluminescence (TRPL) and steady-state PL results show that ZnMgO NPs decreases the QDs’ luminescence more than ZnO NPs and that the behavior continues progressively over time. The surface topography of the samples containing different ETLs is studied using atomic force microscopy (AFM) and optical PL images. Additionally, time of flight secondary ion mass spectroscopy (TOF-SIMS) measurements are conducted to investigate the potential diffusion of some species from ETL into the QDs layer. The results confirm that morphological changes and out-diffusion of some species from the ZnMgO layer can likely play a role in the QDs PL quenching. This study sheds light on the limitations of ZnMgO for the long-term stability of QLEDs, specifically for blue QLEDs where using ZnMgO is essential for efficient electron injection.

Exploiting coordination between poly (ethylene glycol) bis (carboxymethyl) ether and SnO2 for high-performance perovskite photodetectors

In perovskite detectors that utilize SnO₂ as an electron transport layer (ETL), the preparation of SnO₂ films using the solution method results in a significant number of defects. Additionally, the presence of nano-aggregates in the aqueous solution of untreated SnO₂ colloids leads to surface unevenness in SnO₂ films prepared using the spin-coating method, which can affect the growth and crystallization of perovskite. Defects and surface unevenness in SnO₂ films affect the performance of perovskite detectors. To further optimize the performance of perovskite detectors, SnO₂ incorporating poly (ethylene glycol) bis (carboxymethyl) ether (PBE) was developed, employing the polymer as a modifier. The results of the study showed that the incorporation of PBE had two effects: 1) the ether oxygen within the PBE forms a coordination bond with SnO₂, thereby reducing oxygen vacancies, and 2) reducing nano-aggregation of SnO₂ colloidal aqueous solutions, obtaining more uniform SnO₂ films, and promoting the growth and crystallization of perovskite. Ultimately, the performance of the optimized device was improved. The external quantum efficiency (EQE) improved from 84.82 % to 89.29 %, the dark current density decreased from 3.27 × 10-⁹ A cm-² to 1.03 × 10-¹⁰ A cm-², the linear dynamic range (LDR) increased from 88.5 to 118.3 dB, and the stability was enhanced. The device maintained 64.9 % of its original efficiency after being stored for 23 days at 25 °C and 20–30 % humidity.

Nanoscale interface engineering for enhanced performance in light-emitting-diode devices: ITO/Ag-SRCOOH

In light-emitting diode (LED) devices, the hole-injection layer (HIL) reduces the hole injection barrier (HIB) between the anode and organic layers to obtain favorable conditions for hole transport, which considerably affects device efficiency and performance. However, the fabrication of ultrathin silver (Ag) films for electron and hole transport layers remains challenging. We demonstrated the design of a nanoscale HIL interface with chemisorption-bonded carboxylic acid-terminated alkanethiol self-assembled layers on ultrathin Ag. The device structure consisted of indium tin oxide (ITO)/Ag-mercaptan acid (Ag-SRCOOH)/N, Nj-Di (1-naphthyl)-N,Nj-diphenyl-(1,1-biphenyl)-4,4-diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq3)/ETL(LiF/Al. Notably, a chemical bond peak was not detected between ITO and ultrathin Ag. However, X-ray photoelectron spectroscopy (XPS) measurements confirmed Ag binding to the thiol group of 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) on the Ag island surface, which is evident from -S-Ag- and -RS-Ag- association peaks. Ultraviolet photoelectron spectroscopy analysis results revealed a reduction in the HIB of device from 0.68 to 0.19 eV. Consequently, the luminance and current density, and current density of the AgNP–MPA device increased by 63-fold, 5.8-fold, and 1.1-fold, respectively. Similarly, the AgNP-MUA device exhibited enhanced performance with a 61-fold increase in luminance, 43-fold increase in current density, and a 1.4-fold increase in current efficiency, respectively. The results of this study not only opened novel avenues for future applications, including operation requiring flexibility and transparency of LEDs, but also proposed the optimization of nanoscale interfaces to enhance LED performance.

Suppressing leakage current and charge accumulation via perovskite interface morphology regulation for efficient light-emitting diodes

Charge carriers will recombine outside the emitting layer (EML) in non-ideal perovskite light-emitting diodes (PeLEDs), which can lead to parasitic loss and be detrimental to the performance of PeLEDs. Here, we have subtly utilized the property of perovskite nanocrystals (NCs) to design and optimize the homogeneity and optical property of EML, thereby suppressing the undesired carrier loss behavior in system. Photoluminescence (PL) spectra with transmission electron microscopy (TEM) images show that smaller and more homogeneous NCs in size are obtained by temperature-controlled (TC) method. Atomic force microscopy (AFM) images and temperature-dependent PL spectra show that EML with better optical property and uniformity is fabricated. The multiscale capacitance characterization shows that the device with modified EML exhibits significantly reduced leakage current, while the increased specific surface area between electron transport layer (ETL) and EML substantially reduces charge accumulation. Additionally, multiscale reactance, impedance and phase angle responses, reveal that the carrier oscillation behavior in the optimized device is suppressed compared to control group, leading to less energy loss. Consequently, the optimized devices exhibit lower leakage current and superior electroluminescent properties. The luminance is increased from 31650 cd/m2 to 72941 cd/m2, current efficiency (CE) is improved from 59.9 cd/A to 94.3 cd/A, and the external quantum efficiency (EQE) rises from 12.6 % to 19.7 %, corresponding to improvement of 230 %, 157 %, and 156 %, respectively. This research provides valuable insight into the impact of functional layer morphology on carrier dynamic behavior in PeLEDs.