Search Results (17)

In recent years, there has been significant investigation into the high efficiency of perovskite solar cells. These cells have the capacity to attain efficiencies above 14%. As the perovskite materials that include lead pose a substantial environmental risk, components that are free from lead are used during the process of solar cell development. In this work, we use a lead-free double-perovskite material, namely Cs₂TiBr₆, as the main absorbing layer in perovskite solar cells to enhance power conversion efficiency (PCE). This work is centered on the development of solar cell structures with materials such as an ETL (electron transport layer) and an HTL (hole transport layer) to enhance the PCE. In this theoretical work, we perform simulations and analysis on double-perovskite Cs₂TiBr₆ to assess its efficacy as an absorber material in various HTLs like Cu₂O and CuI, with a fixed ETL of C60 using SCAPS (Solar Cell Capacitance Simulator, SCAPS 3.3.10) Software. This is a one-dimensional solar cell simulation program. In this work, the thickness of the double-perovskite material is also varied between 0.2 and 2.0 µm, and its efficiency is observed. The effect of temperature variation on efficiency in the range of 300 K to 350 K is observed. The effect of defect density on efficiency is also observed in the range of 1 × 10¹¹ to 1 × 10¹⁶. In this theoretical work, perovskite solar cells, including their absorbing layer, demonstrate outstanding ETLs and HTLs, respectively. As a result, the cells’ achieved PCE is improved. This work demonstrates the effectiveness of this lead-free double-perovskite structure that absorbs light in perovskite solar cells. Full article

Perovskite solar cells (PSCs) characterized by high energy conversion efficiency (ECE) and low manufacturing costs, exhibit promising potential for commercialization in the near term. For commercialization, it is very important to prevent the decomposition of perovskite by ultraviolet (UV) radiation in the air environment. Also, the mesoscopic architecture of PSCs presents considerable opportunities for the solar cell industry, offering potential for recycling of spent photocatalytic materials such as TiO₂, and exploration of new energy resources. To solve these problems, therefore, this study introduces a strategy to mitigate these challenges using a crystalline Al-doped TiO₂ buffer layer as the electron transport layer (ETL) in conjunction with a mesoporous TiO₂ layer in the fabrication of PSCs. Among various Al concentrations in the crystalline Al-doped TiO₂ buffer layer fabricated via spin-coating, an optimum concentration of 7 mol% Al yielded the highest cell performance in the specific perovskite solar cell structure. These solar cells exhibited an impressive ECE of 11.87%, representing a substantial enhancement of nearly double the ECE (6.37%) achieved with the conventional ETL. This remarkable improvement can be attributed to the passivation effect of the newly developed ETL, which combines a crystalline Al-doped TiO₂ buffer layer with a mesoporousTiO₂ layer. Electrochemical impedance spectroscopy (EIS) analysis was performed in conjunction with theoretical calculations of charge transport parameters to substantiate this claim. Full article

Tin oxide (SnO₂) has been recognized as one of the beneficial components in the electron transport layer (ETL) of lead–halide perovskite solar cells (PSCs) due to its high electron mobility. The SnO₂-based thin film serves for electron extraction and transport in the device, induced by light absorption at the perovskite layer. The focus of this paper is on the heat treatment of a nanoaggregate layer of single-nanometer-scale SnO₂ particles in combination with another metal-dopant precursor to develop a new process for ETL in PSCs. The combined precursor solution of Li chloride and titanium(IV) isopropoxide (TTIP) was deposited onto the SnO₂ layer. We varied the heat treatment conditions of the spin-coated films comprising double layers, i.e., an Li/TTIP precursor layer and SnO₂ nanoparticle layer, to understand the effects of nanoparticle interconnection via sintering and the mixing ratio of the Li-dopant on the photovoltaic performance. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) measurements of the sintered nanoparticles suggested that an Li-doped solid solution of SnO₂ with a small amount of TiO₂ nanoparticles formed via heating. Interestingly, the bandgap of the Li-doped ETL samples was estimated to be 3.45 eV, indicating a narrower bandgap as compared to that of pure SnO₂. This observation also supported the formation of an SnO₂/TiO₂ solid solution in the ETL. The utilization of such a nanoparticulate SnO₂ film in combination with an Li/TTIP precursor could offer a new approach as an alternative to conventional SnO₂ electron transport layers for optimizing the performance of lead–halide perovskite solar cells. Full article

Solar cells can be designed for indoor applications to provide a feasible solution for harnessing photon energy from indoor lighting. In this paper, we analyze the suitability of a selenium-based solar cell for gathering photon energy emitted by indoor light-emitting diodes (LEDs). The absorption band of selenium (Se) is found to be aligned with the LED spectrum, making it a promising contender for efficient indoor applications. In order to simulate the Se-based photovoltaic (PV) device, we started by calibrating the simulation model against a fabricated Se cell that was tested under AM1.5G. After the verification of the physical models and the technological key factors of the different layers incorporated in cell design, a systematic approach was performed to assess the operation of the Se solar cell under an LED light environment. We show an optimized power conversion efficiency (PCE) of 26.93% for the Se-based cell under LED illumination (311 μW/cm²). This is achieved by providing an effective design that incorporates a double-ETL structure, which can significantly improve the band alignment between the different layers of the cell device. The simulation results presented in this work serve to judge the potential of Se solar cells as indoor PVs and offer an approach for providing indoor use specifically designed for internet-of-things (IoT) devices. Full article

This research aims to optimize the efficiency of the device structures by introducing the novel double perovskite absorber layer (PAL). The perovskite solar cell (PSC) has higher efficiency with both lead perovskite (PVK), i.e., methylammonium tin iodide (MASnI₃) and Caseium tin germanium iodide (CsSnGeI₃). The current simulation uses Spiro-OMeTAD as the hole transport layer (HTL) and TiO₂ as an electron transport layer (ETL) to sandwich the PVK layers of MASnI₃ and CsSnGeI₃, which have precise bandgaps of 1.3 eV and 1.5 eV. The exclusive results of the precise modeling technique for organic/inorganic PVK-based photovoltaic solar cells under the illumination of AM1.5 for distinctive device architectures are shown in the present work. Influence of defect density (DD) is also considered during simulation that revealed the best PSC parameters with J_SC of 31.41 mA/cm², V_OC of 1.215 V, FF of nearly 82.62% and the highest efficiency of 31.53% at the combined DD of 1.0 × 10¹⁴ cm⁻³. The influence of temperature on device performance, which showed a reduction in PV parameters at elevated temperature, is also evaluated. A steeper temperature gradient with an average efficiency of −0.0265%/K for the optimized PSC is observed. The novel grading technique helps in achieving efficiency of more than 31% for the optimized device. As a result of the detailed examination of the total DD and temperature dependency of the simulated device, structures are also studied simultaneously. Full article

A desire to achieve optimal electron transport from the electron transport layer (ETL) towards the emissive layer (EML) is an important research factor for the realization of high performance quantum dot light-emitting diodes (QD-LEDs). In this paper, we study the effect of a single, double, and electron transport layer sandwiched Poly(4-vinylpyridine) (PVPy here on) on the charge injection balance and on the overall device performance of InP-based red quantum dot light emitting diodes (red QD-LEDs). The results showed general improvement of device characteristic performance metrics such as operational life with incorporation of a PVPy interlayer. The best performance was observed at a lower concentration of PVPy (@ 0.1 mg/mL) in interlayer with continual worsening in performance as PVPy concentration in the interlayer increased in other fabricated devices. The AFM images obtained for the different materials reported improved surface morphology and overall improved surface properties, but decreased overall device performance as PVPy concentration in interlayer was increased. Furthermore, we fabricated two special devices: in the first special device, a single 0.1 mg/mL PVPy sandwiched between two ZnO ETL layers, and in the second special device, two 0.1 mg/mL PVPy interlayers were inter-sandwiched between two ZnO ETL layers. Particular emphasis was placed on monitoring the maximum obtained EQE and the maximum obtained luminance of all the devices. The first special device showed better all-round improved performance than the second special device compared to the reference device (without PVPy) and the device with a single 0.1 mg/mL PVPy interlayer stacked between ZnO ETL and the emissive layer. Full article

In recent years, inorganic perovskite solar cells (PSCs) based on CsPbI₃ have made significant progress in stability compared to hybrid organic–inorganic PSCs by substituting the volatile organic component with Cs cations. However, the cubic perovskite structure of α-CsPbI₃ changes to the orthorhombic non-perovskite phase at room temperature resulting in efficiency degradation. The partial substitution of an I ion with Br ion benefits for perovskite phase stability. Unfortunately, the substitution of Br ion would enlarge bandgap reducing the absorption spectrum range. To optimize the balance between band gap and stability, introducing and optimizing the spatial bandgap gradation configuration is an effective method to broaden the light absorption and benefit the perovskite phase stability. As the bandgap of the CsPb(I_1–xBr_x)₃ perovskite layer can be adjusted by I-Br composition engineering, the performance of CsPb(I_1–xBr_x)₃ based PSCs with three different spatial variation Br doping composition profiles were investigated. The effects of uniform doping and gradient doping on the performance of PSCs were investigated. The results show that bandgap (Eg) and electron affinity(χ) attributed to an appropriate energy band offset, have the most important effects on PSCs performance. With a positive conduction band offset (CBO) of 0.2 eV at the electron translate layer (ETL)/perovskite interface, and a positive valence band offset (VBO) of 0.24 eV at the hole translate layer (HTL)/perovskite interface, the highest power conversion efficiency (PCE) of 22.90% with open–circuit voltage (V_OC) of 1.39 V, short–circuit current (J_SC) of 20.22 mA/cm² and filling factor (FF) of 81.61% was obtained in uniform doping CsPb(I_1–xBr_x)₃ based PSCs with x = 0.09. By carrying out a further optimization of the uniform doping configuration, the evaluation of a single band gap gradation configuration was investigated. By introducing a back gradation of band gap directed towards the back contact, an optimized band offset (front interface CBO = 0.18 eV, back interface VBO = 0.15 eV) was obtained, increasing the efficiency to 23.03%. Finally, the double gradient doping structure was further evaluated. The highest PCE is 23.18% with V_OC close to 1.44 V, J_SC changes to 19.37 mA/cm² and an FF of 83.31% was obtained. Full article

In this study, we propose a novel silicon (Si)/silicon carbide (4H–SiC) heterojunction vertical double–diffused MOSFET with an electron tunneling layer (ETL) (HT–VDMOS), which improves the specific on–state resistance (R_ON), and examine the hetero–transfer mechanism by simulation. In this structure, the high channel mobility and high breakdown voltage (BV) are obtained simultaneously with the Si channel and the SiC drift region. The heavy doping ETL on the 4H–SiC side of the heterointerface leads to a low heterointerface resistance (R_H), while the R_H in H–VDMOS is extremely high due to the high heterointerface barrier. The higher carrier concentration of the 4H–SiC surface can significantly reduce the width of the heterointerface barrier, which is demonstrated by the comparison of the conductor energy bands of the proposed HT–VDMOS and the general Si/SiC heterojunction VDMOS (H–VDMOS), and the electron tunneling effect is significantly enhanced, leading to a higher tunneling current. As a result, a significantly improved trade–off between R_ON and BV is achieved. With similar BV values (approximately 1525 V), the R_ON of the HT–VDMOS is 88% and 65.75% lower than that of H–VDMOS and the conventional SiC VDMOS, respectively. Full article

Although perovskite solar cells have achieved excellent photoelectric conversion efficiencies, there are still some shortcomings, such as defects inside and at the interface as well as energy level dislocation, which may lead to non-radiative recombination and reduce stability. Therefore, in this study, a double electron transport layer (ETL) structure of FTO/TiO₂/ZnO/(FAPbI₃)_0.85(MAPbBr₃)_0.15/Spiro-OMeTAD is investigated and compared with single ETL structures of FTO/TiO₂/(FAPbI₃)_0.85(MAPbBr₃)_0.15/Spiro-OMeTAD and FTO/ZnO/(FAPbI₃)_0.85(MAPbBr₃)_0.15/Spiro-OMeTAD using the SCAPS-1D simulation software, with special attention paid to the defect density in the perovskite active layer, defect density at the interface between the ETL and the perovskite active layer, and temperature. Simulation results reveal that the proposed double ETL structure could effectively reduce the energy level dislocation and inhibit the non-radiative recombination. The increases in the defect density in the perovskite active layer, the defect density at the interface between the ETL and the perovskite active layer, and the temperature all facilitate carrier recombination. Compared with the single ETL structure, the double ETL structure has a higher tolerance for defect density and temperature. The simulation outcomes also confirm the possibility of preparing a stable perovskite solar cell. Full article

Perovskite solar cells have been researched for high efficiency only in the last few years. These cells could offer an efficiency increase of about 3% to more than 15%. However, lead-based perovskite materials are very harmful to the environment. So, it is imperative to find lead-free materials and use them in designing solar cells. This research investigates the potential for using a lead-free double-perovskite material, La₂NiMnO₆, as an absorbing layer in perovskite solar cells to enhance power conversion efficiency (PCE). Given the urgent need for environmentally friendly energy sources, the study addresses the problem of developing alternative materials to replace lead-based perovskite materials. Compared to single-perovskite materials, double perovskites offer several advantages, such as improved stability, higher efficiency, and broader absorption spectra. In this research work, we have simulated and analyzed a double-perovskite La₂NiMnO₆ as an absorbing material in a variety of electron transport layers (ETLs) and hole transport layers (HTLs) to maximize the capacity for high-efficiency power conversion (PCE). It has been observed that for a perovskite solar cells with La₂NiMnO₆ absorbing layer, C₆₀ and Cu₂O provide good ETLs and HTLs, respectively. Therefore, the achieved power conversion efficiency (PCE) is improved. The study demonstrates that La₂NiMnO₆, as a lead-free double-perovskite material can serve as an effective absorbing layer in perovskite solar cells. The findings of this study contribute to the growing body of research on developing high-efficiency, eco-friendly perovskite solar cell technologies and have important implications for the advancement of renewable energy production. Full article

The advancement of lead-free double perovskite materials has drawn great interest thanks to their reduced toxicity, and superior stability. In this regard, Cs₂AgBiBr₆ perovskites have appeared as prospective materials for photovoltaic (PV) applications. In this work, we present design and numerical simulations, using SCAPS-1D device simulator, of Cs₂AgBiBr₆-based double perovskite solar cell (PSC). The initial calibrated cell is based on an experimental study in which the Cs₂AgBiBr₆ layer has the lowest bandgap (E_g = 1.64 eV) using hydrogenation treatment reported to date. The initial cell (whose structure is ITO/SnO₂/Cs₂AgBiBr₆/Spiro-OMeTAD/Au) achieved a record efficiency of 6.58%. The various parameters that significantly affect cell performance are determined and thoroughly analyzed. It was found that the conduction band offset between the electron transport layer (ETL) and the Cs₂AgBiBr₆ layer is the most critical factor that affects the power conversion efficiency (PCE), in addition to the thickness of the absorber film. Upon engineering these important technological parameters, by proposing a double ETL SnO₂/ZnO_1-xS_x structure with tuned absorber thickness, the PCE can be boosted to 14.23%. Full article

In this paper, a blue fluorescent organic light-emitting diode (OLED) with a 1 cm² emitting area was fabricated by a solution process. The ITO/spin MADN:13% UBD-07/TPBi/Al was used as the basic structure in which to add a hole-injection layer PEDOT:PSS and an electron-injection layer LiF, respectively. The device structure was optimized to obtain a longer lifetime. Firstly, the TPBi, which is an electron transport layer and a hole-blocking layer, was added to the structure to increase the electron transport rate. When the TPBi thickness was increased to 20 nm, the luminance was 221 cd/m², and the efficiency was 0.52 cd/A at a voltage of 8 V. Since the addition of the hole-injection layer (HIL) increased the hole current but did not increase the electron current, the electron transport layer (ETL) Alq₃ with the lowest unoccupied molecular orbital (LUMO) was added as stepped ETL to help the TPBi transport more electron current into the emitting layer. When the thickness of the TPBi/Alq₃ was 10 nm/15 nm, the luminance reached 862 cd/m², the efficiency was 1.29 cd/A, and the lifetime increased to 252 min. Subsequently, a hole-injection layer PEDOT:PSS with a thickness of 55 nm was added to make the ITO surface flatter and to reduce the probability of a short circuit caused by the spike effect. At this time, the luminance of 311 cd/m², the efficiency of 0.64 cd/A, and the lifetime of 121 min were obtained. Following this, the thickness of the emitting layer was doubled to increase the recombination probability of the electrons and the holes. When the thickness of the emitting layer was 90 nm, and the thermal evaporation method was used, the efficiency was 3.23 cd/A at a voltage of 8V, and the lifetime was improved to 482 min. Furthermore, when the thickness of the hole-injection layer PEDOT:PSS was increased to 220 nm, the efficiency increased to 3.86 cd/A, and the lifetime was increased to 529 min. An infrared thermal image camera was employed to detect the temperature variation of the blue OLEDs. After the current was gradually increased, it was found that the heat accumulation of the device became more and more significant. When the driving current reached 50 mA, the device burnt out. It was found that the maximum temperature that the OLED device could withstand was approximately 58.83 degrees C at a current of 36.36 mA. Full article

The widely used ZnO quantum dots (QDs) as an electron transport layer (ETL) in quantum dot light-emitting diodes (QLEDs) have one drawback. That the balancing of electrons and holes has not been effectively exploited due to the low hole blocking potential difference between the valence band (VB) (6.38 eV) of ZnO ETL and (6.3 eV) of CdSe/ZnS QDs. In this study, ZnO QDs chemically reacted with capping ligands of oleic acid (OA) to decrease the work function of 3.15 eV for ZnO QDs to 2.72~3.08 eV for the ZnO-OA QDs due to the charge transfer from ZnO to OA ligands and improve the efficiency for hole blocking as the VB was increased up to 7.22~7.23 eV. Compared to the QLEDs with a single ZnO QDs ETL, the ZnO-OA/ZnO QDs double ETLs optimize the energy level alignment between ZnO QDs and CdSe/ZnS QDs but also make the surface roughness of ZnO QDs smoother. The optimized glass/ITO/PEDOT:PSS/PVK//CdSe/ZnS//ZnO-OA/ZnO/Ag QLEDs enhances the maximum luminance by 5~9% and current efficiency by 16~35% over the QLEDs with a single ZnO QDs ETL, which can be explained in terms of trap-charge limited current (TCLC) and the Fowler-Nordheim (F-N) tunneling conduction mechanism. Full article

In this work, a multi-electron transporting layer (ETL) for efficient perovskite solar cells is investigated. The multi-ETL consists of five conditions including SnO₂, SnO₂/SnO_x, TiO₂, TiO₂/SnO₂, and TiO₂/SnO₂/SnO_x. The best performance of PSC devices is found in the SnO₂/SnO_x double-layer and exhibits a power conversion efficiency equal to 18.39% higher than the device with a TiO₂ single-layer of 14.57%. This enhancement in efficiency can be attributed to a decrease in charge transport resistance (R_ct) and an increase in charge recombination resistance (R_rec). In addition, R_ct and R_rec can be used to explain the comparable power conversion efficiency (PCE) between a PSC with a SnO₂/SnO_x double-layer and a PSC with a triple-layer, which is due to the compensation effect of R_ct and R_rec parameters. Therefore, R_ct and R_rec are good parameters to explain the efficiency enhancement in PSC. Thus, the R_ct and R_rec from the electrochemical impedance spectroscopy (EIS) technique is an easy and alternative way to obtain information to understand and characterize the multi-ETL on PSC. Full article

Zinc Oxide (ZnO) has been regarded as a promising electron transport layer (ETL) in perovskite solar cells (PSCs) owing to its high electron mobility. However, the acid-nonresistance of ZnO could destroy organic-inorganic hybrid halide perovskite such as methylammonium lead triiodide (MAPbI₃) in PSCs, resulting in poor power conversion efficiency (PCE). It is demonstrated in this work that Nb₂O₅/ZnO films were deposited at room temperature with RF magnetron sputtering and were successfully used as double electron transport layers (DETL) in PSCs due to the energy band matching between Nb₂O₅ and MAPbI₃ as well as ZnO. In addition, the insertion of Nb₂O₅ between ZnO and MAPbI₃ facilitated the stability of the perovskite film. A systematic investigation of the ZnO deposition time on the PCE has been carried out. A deposition time of five minutes achieved a ZnO layer in the PSCs with the highest power conversion efficiency of up to 13.8%. This excellent photovoltaic property was caused by the excellent light absorption property of the high-quality perovskite film and a fast electron extraction at the perovskite/DETL interface. Full article