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This article reviews the latest advancements in perovskite solar cell (PSC) components for innovative photovoltaic applications. Perovskite materials have emerged as promising candidates for next-generation solar cells due to their exceptional light-absorbing capabilities and facile fabrication processes. However, limitations in their stability, scalability, and efficiency have hindered their widespread adoption. This review systematically explores recent breakthroughs in PSC components, focusing on absorbed layer engineering, electron and hole transport layers, and interface materials. In particular, it discusses novel perovskite compositions, crystal structures, and manufacturing techniques that enhance stability and scalability. Additionally, the review evaluates strategies to improve charge carrier mobility, reduce recombination, and address environmental considerations. Emphasis is placed on scalable manufacturing methods suitable for large-scale integration into existing infrastructure. This comprehensive review thus provides researchers, engineers, and policymakers with the key information needed to motivate the further advancements required for the transformative integration of PSCs into global energy production. [ABSTRACT FROM AUTHOR]

This study focuses on the teaching of electron transport layer materials within the Traditional Energy and New Energy curriculum, using perovskite solar cells as a starting point. It integrates the cutting-edge research on chemical bath deposition (CBD) of tin oxide (SnO2) electron transport layers into teaching practice. The study employs scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL) to characterize the SnO2 thin films prepared by CBD. It then applies these films to fabricate perovskite solar cells, evaluating their impact on device performance. The results show that compared to SnO2 thin films prepared by the traditional spin-coating method, those prepared by CBD are more uniform and denser, exhibit better crystallinity and higher electron extraction capability, ultimately achieving higher device efficiency. This research constructs a “Theory-Practice-Inquiry-Innovation” teaching model. By designing a teaching experiment on CBD of SnO2 electron transport layers, it effectively enhances students' learning interest, deepens their understanding of theoretical knowledge and stimulates their enthusiasm for exploring the field of new energy. This research provides a new approach for experimental teaching reform in universities and holds significant importance for cultivating new energy talents with practical skills and an innovative spirit. [ABSTRACT FROM AUTHOR]

In this paper, we study the effects of Cu, Ni, and Zn doping in TiO2 layers on the performance of MAPbI3-based perovskite solar cells (PSCs) fabricated under ambient air with relative humidity between 60% and 70%. One of the factors limiting the efficiency of MAPbI3-based PSCs is the TiO2 electron transport layer properties. The efficiency of PSCs is the maximum power that can be produced by a PSC when illuminated by light with a specific energy. This study aims to enhance MAPbI3-based PSC efficiency by doping TiO2 with 2 mol.% Cu, Ni, and Zn. MAPbI3-based PSCs were then fabricated using spin coating with the structure ITO/TiO2/MAPbI3/graphite/ITO. X-ray diffraction and scanning electron microscopy (SEM) analyses revealed that doping reduced TiO2 crystal sizes from 19.34 nm (pure) to 18.96 nm (Cu-doped), 18.04 nm (Ni-doped), and 17.6 nm (Zn-doped), with corresponding average particle sizes of 225 nm, 107 nm, 79 nm, and 50.4 nm. Ultraviolet–visible (UV–Vis) spectroscopy indicated an increase in the bandgap from 3.0 eV (pure) to 3.1 eV (Cu-doped), 3.2 eV (Ni-doped), and 3.25 eV (Zn-doped). Current–voltage (I–V) electrical testing revealed improvement in efficiency from 5.7% (undoped) to 7.6% (Cu-doped), 6.9% (Ni-doped), and 8.01% (Zn-doped). These findings demonstrate that metal-doped TiO2 significantly enhances the efficiency of MAPbI3-based PSCs fabricated in open-air environments without the need for a glove box. [ABSTRACT FROM AUTHOR]

We developed inverted red quantum dot light-emitting diodes (QLEDs) with ZnO nanoparticles synthesized in open and closed systems. Wurtzite-structured ZnO nanoparticles were synthesized using potassium hydroxide and zinc acetate dihydrate at various temperatures in the open and closed systems. The particle size increases with increasing synthesis temperature. The ZnO nanoparticles synthesized at 50, 60, and 70 °C in the closed system have an average particle size of 3.2, 4.0, and 5.4 nm, respectively. The particle size is larger in the open system compared to the closed system as the methanol solvent evaporates during the synthesis process. The surface defect-induced emission in ZnO nanoparticles shifts to a longer wavelength and the emission intensity decreases as the synthesis temperature increases. The inverted red QLEDs were fabricated with a synthesized ZnO nanoparticle electron transport layer. The driving voltage of the inverted QLEDs decreases as the synthesis temperature increases. The current efficiency is higher in the inverted red QLEDs with the ZnO nanoparticles synthesized in the closed system compared to the devices with the nanoparticles synthesized in the open system. The device with the ZnO nanoparticles synthesized at 60 °C in the closed system exhibits the maximum current efficiency of 5.8 cd/A. [ABSTRACT FROM AUTHOR]

Sol–gel processed zinc oxide (ZnO) is one of the most widely used electron transport layers (ETLs) in inverted organic solar cells (OSCs). The high annealing temperature (≈200 °C) required for sintering to ensure a high electron mobility however results in severe damage to flexible substrates. Thus, flexible organic solar cells based on sol–gel processed ZnO exhibit significantly lower efficiency than rigid devices. In this paper, an indium‐doping approach is developed to improve the optoelectronic properties of ZnO layers and reduce the required annealing temperature. Inverted OSCs based on In‐doped ZnO (IZO) exhibit a higher efficiency than those based on ZnO for a range of different active layer systems. For the PM6:L8‐BO system, the efficiency increases from 17.0% for the pristine ZnO‐based device to 17.8% for the IZO‐based device. The IZO‐based device with an active layer of PM6:L8‐BO:BTP‐eC9 exhibits an even higher efficiency of up to 18.1%. In addition, a 1.2‐micrometer‐thick inverted ultrathin flexible organic solar cell is fabricated based on the IZO ETL that achieves an efficiency of 17.0% with a power‐per‐weight ratio of 40.4 W g−1, which is one of the highest efficiency for ultrathin (less than 10 micrometers) flexible organic solar cells. [ABSTRACT FROM AUTHOR]

When implementing optoelectronic devices through the stacking of heterogeneous materials, considering the bandgap offset is crucial for achieving efficient carrier dynamics. In this study, the bandgap offset characteristics are investigated when n‐type gallium nitride nanowires (n‐GaN NWs) are used as electron transport layers in methylammonium lead iodide (MAPbI3)‐based optoelectronic devices. n‐GaN NWs are grown on indium‐tin‐oxide (ITO)‐coated glass via the plasma‐assisted molecular beam epitaxy (PA‐MBE) process to form the "GaN NWs‐on‐glass" platform. A MAPbI3 thin film is then spin‐coated on the GaN NWs‐on‐glass. X‐ray photoelectron spectroscopy (XPS) shows that the valence and conduction band offsets in the MAPbI3/n‐GaN heterostructure are 2.19 and 0.40 eV, respectively, indicating a type‐II band alignment ideal for optoelectronic applications. Prototype photovoltaic devices stacking perovskite on GaN NWs‐on‐glass show excellent interfacial charge‐transfer ability, photon recycling, and carrier extraction efficiency. As a pioneering step in exploiting the diverse potential of the GaN‐on‐glass, it is demonstrated that the junction characteristics of MAPbI3/n‐GaN NW heterostructures can lead to a variety of optoelectronic device applications. [ABSTRACT FROM AUTHOR]

The buried interface between the electron transport layer (ETL) and the perovskite layer plays a crucial role in enhancing the power conversion efficiency (PCE) and stability of n–i–p type perovskite solar cells (PSCs). In this study, the interface between the chemical bath deposited (CBD) titanium oxide (TiO2) ETL and the perovskite layer using multi‐functional potassium trifluoromethyl sulfonate (SK) is modified. Structural and elemental analyses reveal that the trifluoromethyl sulfonate serves as a crosslinker between the TiO2 and the perovskite layer, thus improving the adhesion of the perovskite to the TiO2 ETL through strong bonding of the ─CF3 and ─SO3− terminal groups. Furthermore, the multi‐functional modifiers reduced interface defects and suppressed carrier recombination in the PSCs. Consequently, devices with a champion PCE of 25.22% and a fill factor (FF) close to 85% is achieved, marking the highest PCE and FF observed for PSCs based on CBD TiO2. The unencapsulated device maintained 81.3% of its initial PCE after operating for 1000 h. [ABSTRACT FROM AUTHOR]

Planar perovskite solar cells (PSCs), as a promising photovoltaic technology, have been extensively studied, with strong expectations for commercialization. Improving the power conversion efficiency (PCE) of PSCs is necessary to accelerate their practical application, in which the electron transport layer (ETL) plays a key part. Herein, a single-anchored ligand of phenylphosphonic acid (PPA) is utilized to regulate the chemical bath deposition of a TiO2 ETL, further improving the PCE of planar PSCs. The PPA possesses a steric benzene ring and a phosphoric acid group, which can inhibit the particle aggregation of the TiO2 film through steric hindrance, leading to optimized interface (ETL/perovskite) contact. In addition, the incorporated PPA can induce the upshift of the Fermi-level of the TiO2 film, which is beneficial for interfacial electron transport. As a consequence, the PSCs with PPA-TiO2 achieve a PCE of 24.83%, which is higher than that (24.21%) of PSCs with TiO2. In addition, the unencapsulated PSCs with PPA-TiO2 also exhibit enhanced stability when stored in ambient conditions. [ABSTRACT FROM AUTHOR]

The assessment of electron transport layer (ETL) for rear-contact engineering of silicon (Si) based optoelectronics has been considered as one of the critical challenges that leverage the performance improvement and device reliability. In this work, the hybrid design of ETL, obtained from the solution-processed nitrogen-doped carbon quantum dots (NCQDs) incorporated with organic polyethylenimine (PEI) demonstrates the feasible contact characteristics for the modification of Si/Al contacts, which greatly facilitates the transport and collection of photoexcited electrons in the Si-based optoelectronics. The aspects of microstructures, functional groups, chemical features, interfacial characteristics and band structures of NCQD/PEI are explicated, visualizing that the evolution of interface dipoles mediated by the overall outcome of physisorption and chemisorption effects, modifies the surface potential difference and results in the explicit reduction of the Al work function from 4.3 eV for pristine Al to 3.23 eV based on the optimized constitutional design (0.10 % NCQD in PEI). These findings are practically employed on the Si-based hybrid solar cells at Si/Al interfaces, fulfilling the conversion-efficiency improvement by 30.9 % compared with reference cells without ETL employment, which are experimentally interpreted by the efficient electron transport across the Si/Al heterojunction and charge collection.

Abstract Perovskite solar cells (PSCs) have gained much attention in recent years because of their improved energy conversion efficiency, simple fabrication process, low processing temperature, flexibility, light weight, and low cost of constituent materials when compared with their counterpart silicon based solar cells. Besides, stability and toxicity of PSCs and low power conversion efficiency have been an obstacle towards commercialization of PSCs which has attracted intense research attention. In this research paper, a Glass/Cu2O/CH3NH3SnI3/ZnO/Al inverted device structure which is made of cheap inorganic materials, n-type transparent conducting oxide (TCO)-free, stable, photoexcited toxic-free perovskite have been carefully designed, simulated and optimized using a one-dimensional solar cell capacitance simulator (SCAPS-1D) software. The effects of layers’ thickness, perovskite’s doping concentration and back contact electrodes have been investigated, and the optimized structure produced an open circuit voltage (Voc) of 1.0867 V, short circuit current density (JSC) of 33.4942 mA/cm2, fill factor (FF) of 82.88% and power conversion efficiency (PCE) of 30.17%. This paper presents a model that is first of its kind where the highest PCE performance and eco-friendly n-type TCO-free inverted CH3NH3SnI3 based perovskite solar cell is achieved using all-inorganic transport materials.

Highlights Developing a universal strategy of the p–n homojunction engineering that could significantly boost electron mobility of electron transport layer (ETL) by two orders of magnitude. Proposing a new mechanism based on p–n homojunction to explain inhibited carrier loss at buried interface. Setting a new performance benchmark as high as 25.50% for planar perovskite solar cells employing TiO2 as ETLs.

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. [ABSTRACT FROM AUTHOR]

This study investigated the fabrication and characterization of CH3NH3PbI3 based perovskite solar cells (PSCs) using the one-step spin coating technique under ambient conditions, eliminating the need for expensive glovebox and thermal evaporation equipment. The perovskite layer was annealed at 65 °C for 30 seconds and 100 °C for 30 seconds, 1 and 2 minutes. The scanning electron microscope (SEM) images show a smooth and uniform surface coverage for the ETL and CH3NH3PbI3 layers. SEM results also show an average grain size of 397 nm for CH3NH3PbI3 and an average particle size of ~17 nm for TiO2 was confirmed by transmission electron microscopy (TEM). X-ray diffraction (XRD) results confirmed the formation of tetragonal perovskite (CH3NH3PbI3) phase with high crystallinity with a crystallite size of 19.99 nm for the samples annealed for 30 seconds at 65 °C and 1 min at 100 °C. FTIR results also confirmed the presence of anatase TiO2 at wavenumber 438 cm-1 and the formation of the adduct of Pb2 with dimethyl sulfoxide (DMSO) and MAI is confirmed at 1,015 cm-1. From the Tauc plot the bandgap energy of TiO2 and Perovskite layers was determined to be 3.52 eV and 2.06 eV respectively. An open-circuit voltage was 0.9057 V and short circuit current density was 12.2185 mA/cm² with a fill factor of 48.05 and power conversion efficiency (PCE) of 5.199%. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have gained much attention in recent years because of their improved energy conversion efficiency, simple fabrication process, low processing temperature, flexibility, light weight, and low cost of constituent materials when compared with their counterpart silicon based solar cells. Besides, stability and toxicity of PSCs and low power conversion efficiency have been an obstacle towards commercialization of PSCs which has attracted intense research attention. In this research paper, a Glass/Cu2O/CH3NH3SnI3/ZnO/Al inverted device structure which is made of cheap inorganic materials, n-type transparent conducting oxide (TCO)-free, stable, photoexcited toxic-free perovskite have been carefully designed, simulated and optimized using a one-dimensional solar cell capacitance simulator (SCAPS-1D) software. The effects of layers' thickness, perovskite's doping concentration and back contact electrodes have been investigated, and the optimized structure produced an open circuit voltage (Voc) of 1.0867 V, short circuit current density (JSC) of 33.4942 mA/cm2, fill factor (FF) of 82.88% and power conversion efficiency (PCE) of 30.17%. This paper presents a model that is first of its kind where the highest PCE performance and eco-friendly n-type TCO-free inverted CH3NH3SnI3 based perovskite solar cell is achieved using all-inorganic transport materials. [ABSTRACT FROM AUTHOR]

At present, heavy-metal-free quantum dot light-emitting diodes (QLEDs) have shown great potential as a research hotspot in the field of optoelectronic devices. This article reviews the research on heavy-metal-free quantum dot (QD) materials and light-emitting diode (LED) devices. In the first section, we discussed the hazards of heavy-metal-containing quantum dots (QDs), such as environmental pollution and human health risks. Next, the main representatives of heavy-metal-free QDs were introduced, such as InP, ZnE (E=S, Se and Te), CuInS2, Ag2S, and so on. In the next section, we discussed the synthesis methods of heavy-metal-free QDs, including the hot injection (HI) method, the heat up (HU) method, the cation exchange (CE) method, the successful ionic layer adsorption and reaction (SILAR) method, and so on. Finally, important progress in the development of heavy-metal-free QLEDs was summarized in three aspects (QD emitter layer, hole transport layer, and electron transport layer). [ABSTRACT FROM AUTHOR]

Context: Density functional theory (DFT) calculations are carried out on pure and doped rutile TiO 2 . The bandgap (E g ) for pristine, S-doped, Fe-doped, and Fe/S co-doped materials is direct, with values of 2.98 eV, 2.18 eV, 1.58 eV, and 1.40 eV. The effective mass of charge carriers (m*) and ratio of effective masses of holes to effective masses of electrons (R) are also investigated, and it is discovered that Fe/S co-doped materials have the lowest charge carrier recombination rate. The Fe/S co-doped material has the highest ε (ω) . α (ω) of doped materials shifted into the visible range. Due to the high dopant concentration in Fe and Fe/S-doped cases, the E g is lowered to a relatively small value; hence, only pristine and S-doped materials are verified as electron transport layer (ETL). A solar cell device analysis employing pure and S-doped rutile TiO 2 as ETL is completed using DFT-derived parameters in SCAPS-1D modeling software for the first time. For the optimized solar cells, current–voltage (IV) characteristics, quantum efficiency (QE), capacitance-voltage (CV) characteristics, and capacitance-frequency (Cf) characteristics are provided. The aim of the present study is to improve efficiency of perovskite solar cell by doping as well as to improve accuracy of simulation by applying DFT extracted parameters as input. From the analysis, improvement is found in efficiency of doped TiO 2 compared to un-doped TiO 2 . The efficiency of the PSC with S-doped ETL is 1.418% higher than the PSC with un-doped ETL. Method: Quantumwise Automistic Tool Kit (ATK) is used to extract DFT parameters. Using these DFT parameters as input in SCAPS-1D (Solar Cell Capacitance Simulator), solar cells for doped and un-doped material are simulated. The density functional theory (DFT)-based orthogonalized linear combination of atomic orbital (OLCAO) technique is used. Structural optimization is done using the LBFGS (Limited-memory Broyden-Fletcher-Goldfarb-Shanno). PBESol-GGA (Perdew-Burke-Ernzerhof solid-generalized gradient approximation) is applied as exchange correlation for calculating structural parameters, while MGGA-TB09 (meta-generalized gradient approximation-Tran and Blaha) is applied as exchange correlation for calculating optical and electronic properties. [ABSTRACT FROM AUTHOR]

Highlights: Developing a universal strategy of the p–n homojunction engineering that could significantly boost electron mobility of electron transport layer (ETL) by two orders of magnitude. Proposing a new mechanism based on p–n homojunction to explain inhibited carrier loss at buried interface. Setting a new performance benchmark as high as 25.50% for planar perovskite solar cells employing TiO2 as ETLs. Low-temperature processed electron transport layer (ETL) of TiO2 that is widely used in planar perovskite solar cells (PSCs) has inherent low carrier mobility, resulting in insufficient photogenerated electron transport and thus recombination loss at buried interface. Herein, we demonstrate an effective strategy of laser embedding of p-n homojunctions in the TiO2 ETL to accelerate electron transport in PSCs, through localized build-in electric fields that enables boosted electron mobility by two orders of magnitude. Such embedding is found significantly helpful for not only the enhanced crystallization quality of TiO2 ETL, but the fabrication of perovskite films with larger-grain and the less-trap-states. The embedded p–n homojunction enables also the modulation of interfacial energy level between perovskite layers and ETLs, favoring for the reduced voltage deficit of PSCs. Benefiting from these merits, the formamidinium lead iodide (FAPbI3) PSCs employing such ETLs deliver a champion efficiency of 25.50%, along with much-improved device stability under harsh conditions, i.e., maintain over 95% of their initial efficiency after operation at maximum power point under continuous heat and illumination for 500 h, as well as mixed-cation PSCs with a champion efficiency of 22.02% and over 3000 h of ambient storage under humidity stability of 40%. Present study offers new possibilities of regulating charge transport layers via p-n homojunction embedding for high performance optoelectronics. [ABSTRACT FROM AUTHOR]

Compared to organic–inorganic hybrid perovskites, the cesium‐based all‐inorganic lead halide perovskite (CsPbI3) is a promising light absorber for perovskite solar cells owing to its higher resistance to thermal stress. Nonetheless, additional research is required to reduce the nonradiative recombination to realize the full potential of CsPbI3. Here, the diffusion of Cs ions participating in ion exchange is proposed to be an important factor responsible for the bulk defects in γ‐CsPbI3 perovskite. Calculations based on first‐principles density functional theory reveal that the [PbI6]4− octahedral tilt modifies the perovskite crystallographic properties in γ‐CsPbI3, leading to alterations in its bandgap and crystal strain. In addition, by substituting amorphous barium titanium oxide (a‐BaTiO3) for TiO2 as the electron transport layer, interfacial defects caused by imperfect energy levels between the electron transport layer and perovskite are reduced. High‐resolution transmission electron microscopy and electron energy loss spectroscopy demonstrate that a‐BaTiO3 forms entirely as a single phase, as opposed to Ba‐doped TiO2 hybrid nanoclusters or separate domains of TiO2 and BaTiO3 phases. Accordingly, inorganic perovskite solar cells based on the a‐BaTiO3 electron transport layer achieved a power conversion efficiency of 19.96%. [ABSTRACT FROM AUTHOR]

Abstract When implementing optoelectronic devices through the stacking of heterogeneous materials, considering the bandgap offset is crucial for achieving efficient carrier dynamics. In this study, the bandgap offset characteristics are investigated when n‐type gallium nitride nanowires (n‐GaN NWs) are used as electron transport layers in methylammonium lead iodide (MAPbI3)‐based optoelectronic devices. n‐GaN NWs are grown on indium‐tin‐oxide (ITO)‐coated glass via the plasma‐assisted molecular beam epitaxy (PA‐MBE) process to form the “GaN NWs‐on‐glass” platform. A MAPbI3 thin film is then spin‐coated on the GaN NWs‐on‐glass. X‐ray photoelectron spectroscopy (XPS) shows that the valence and conduction band offsets in the MAPbI3/n‐GaN heterostructure are 2.19 and 0.40 eV, respectively, indicating a type‐II band alignment ideal for optoelectronic applications. Prototype photovoltaic devices stacking perovskite on GaN NWs‐on‐glass show excellent interfacial charge‐transfer ability, photon recycling, and carrier extraction efficiency. As a pioneering step in exploiting the diverse potential of the GaN‐on‐glass, it is demonstrated that the junction characteristics of MAPbI3/n‐GaN NW heterostructures can lead to a variety of optoelectronic device applications.

Perovskite solar cells (PSCs) have experienced an unprecedented advancement in the last decade owing to their astonishingly attractive properties, especially high-power conversion efficiency (PCE). In this study, the influence of reduced graphene oxide (rGO) on the photovoltaic performance of perovskite solar cells prepared via solution processes-based spin coating method was investigated. X-ray Diffraction (XRD), Fourier Transform Infrared spectrometer (FTIR), UV-visible spectrophotometry, Scanning Electron Microscopy (SEM) were used to study the properties of the prepared films. ITO/MAPbBr3/Gr and ITO/rGO/MAPbBr3/Gr planar PSCs were fabricated via spin coating method. ITO/rGO/MAPbBr3/Gr film achieved a power conversion efficiency (PCE) of 4.1 short circuit current (Jsc) of 7.5 mAcm−2 and fill factor (FF) of 61.2% compared to a PCE of 3.6%, Jsc of 6.6 mAcm−2 and FF of 58.0% achieved compared to PCE of 3.6%, %, Jsc of 6.6 mAcm−2 and FF of 58.0% achieved by ITO/MAPbBr3/Gr film. The PSC demonstrated the percentage enhancement value of 16.80% when modified with rGO. This study shows that rGO generated functional groups that act as conducting bridge in reducing the contact resistance between interface of the device.

Abstract MXenes, a class of two-dimensional (2D) transition metal carbides and nitrides, have a wide range of potential applications due to their unique electronic, optical, plasmonic, and other properties. SnO2–Ti3C2 MXene with different contents of Ti3C2 (0.5, 1.0, 2.0, 2.5 wt‰), experimentally, has been used as electron transport layers (ETLs) in Perovskite Solar Cells (PSCs). The SCAPS-1D simulation software could simulate a perovskite solar cell comprised of CH3NH3PbI3 absorber and SnO2 (or SnO2–Ti3C2) ETL. The simulation results like Power Conversion Efficiency (PCE), Open circuit voltage (VOC), Short circuit current density (JSC), Fill Factor (FF), and External Quantum Efficiency (EQE) have been compared within samples with different weight percentages of Ti3C2 MXene incorporated in ETL. Reportedly, the ETL of SnO2 with Ti3C2 (1.0 wt‰) effectively increases PCE from 17.32 to 18.32%. We simulate the role of MXene in changing the ideality factor (nid), photocurrent (JPh), built-in potential (Vbi), and recombination resistance (Rrec). The study of interface recombination currents and electric field shows that cells with 1.0 wt‰ of MXene in SnO2 ETL have higher values of ideality factor, built-in potential, and recombination resistance. The correlation between these values and cell performance allows one to conclude the best cell performance for the sample with 1.0 wt‰ of MXene in SnO2 ETL. With an optimization procedure for this cell, an efficiency of 27.81% is reachable.

High power conversion efficiency (PCE) flexible perovskite solar cells (FPSCs) are highly desired power sources for aerospace crafts and flexible electronics. However, their PCEs still lag far behind their rigid counterparts. Herein, we report a high PCE FPSC by controllable growth of a SnO2 electron transport layer through constant pH chemical bath deposition (CBD). The application of SnSO4 as tin source enables us to perform CBD without strong acid, which in turn makes it applicable to acid-sensitive flexible indium tin oxide. Furthermore, a mild and controllable growth environment leads to uniform particle growth and dense SnO2 deposition with full coverage and reproducibility, resulting in a record PCE of up to 25.09% (certified 24.90%) for FPSCs to date. The as-fabricated FPSCs exhibited high durability, maintaining over 90% of their initial PCE after 10000 bending cycles.

Abstract In recent years, the power conversion efficiency (PCE (%)) of perovskite solar cells (PSCs) has improved to over 26%. To enhance the photovoltaic properties of PSCs, several materials for the electron transport layer (ETL) have been investigated. Zinc oxide (ZnO) is a significant ETL due to its high electron mobility and optical transparency in PSCs. As a result of various deposition methods, ZnO ETL can be processed at low temperatures. On the other hand, based on several studies, metal-doped ZnO can facilitate electron transfer, thereby improving the performance of un-doped ZnO ETL-based PSCs. Here, to improve the PCE (%) and long-term stability of un-doped ZnO ETL-PSCs, silver (Ag)-doped ZnO 1wt% as a buffer layer is examined. In this paper, with the addition of an organic solvent (ethanol) to the dispersion of Ag-doped ZnO 1 wt% nanoparticles (NPs) in deionized (DI) water, the morphology of the buffer layer (Ag-doped ZnO 1 wt%) can be controlled. This approach focuses on reducing the wettability of the ZnO/Ag-doped ZnO 1 wt% bilayer ETLs and enhancing the stability of un-doped ZnO ETL-PSCs. According to the results, the ZnO/H2O-ethanol mixtures-Ag-doped ZnO 1 wt% bilayer ETL leads to the formation of high-quality perovskite with low defects, reducing the recombination rate, and long-term stability of un-doped ZnO ETL-PSCs in ambient conditions.

The efficiency of organic solar cells (OSCs) is influenced by various factors, among which environmental temperature plays a significant role. Previous studies have shown that the thermal stability of these cells can be enhanced by incorporating a third component into their structure. Ternary organic solar cells, particularly, have shown promising results in improving thermal stability. A well-designed electron transport layer (ETL) can significantly bolster thermal stability by facilitating efficient charge transport and reducing charge recombination. In this study, we investigated the effect of temperature, ranging from 300 K to 400 K, on the efficiency of inverted ternary structures by using a one-dimension optoelectronic model on “Oghma-Nano 8.0.034” software. The structures examined include (S1) “FTO/SnO2/PM6:D18:L8-BO/PEDOT: PSS/Ag”, (S2): “FTO/C60/PM6:D18:L8-BO/PEDOT: PSS/Ag”, and (S3): “FTO/PC60BM/PM6:D18:L8-BO/PEDOT: PSS/Ag”. Simulations using three different ETLs—SnO2, C60, and PC60BM—at 340 K (66.85 °C) resulted in a main effect on open circuit voltage (Voc) and fill factor (FF) values, in addition to an important Jsc value in terms of thermally stable devices. However, these structures retained 92% of their initial ~20% efficiency observed at 300 K, demonstrating significant thermal stability under high power conversion efficiency (PCE) conditions.

Not only can perovskite solar cells be exposed to high temperatures, up to 80 °C, depending on the operating environment, but absorbed energy is lost as heat, so it is important to have thermal stability for commercialization. However, in the case of the recently reported p-i-n structure solar cell, most of the electron and hole transport layers are composed of organic materials vulnerable to heat transfer, so the light absorption layer may be continuously exposed to high temperatures when the solar cell is operated. In this study, we attempted to improve the thermal conductivity of the electron transport layer using phenyl-C61-butyric acid methyl ester (PCBM) containing zinc oxide (ZnO). As a result, the thermal conductivity was improved by more than 7.4% and 23.5% by adding 6.57vol% and 22.38vol% of ZnO to PCBM, respectively. In addition, the insertion of ZnO resulted in changes in the electron transport behavior and energy level of the electron transport layer. As a result, it was confirmed that not only could the temperature stability of the perovskite thin film be improved, but the efficiency of the solar cell could also be improved from 14.12% to 17.97%. [ABSTRACT FROM AUTHOR]

The tetragonal crystal structured anatase titanium dioxide (TiO2) has been conventionally used as an electron transport layer in emerging solar cells. Conventionally, a high-temperature process above 450 °C is indispensable to form crystallized TiO2 films with a well-defined mesoporous structure. Due to the temperature limitations of the flexible polymer substrates, notably below 150 °C, such a high-temperature process is ineffective for flexible emerging solar cells. Currently, cutting-edge and high-potential solar cells are flexible dye-sensitized and perovskite solar cells which are preeminent in mass production due to their roll-to-roll printing technique. Hence, this study explores a low-temperature synthesis of crystallized TiO2 layers using the sol-gel method with various precursor concentrations of titanium tetraisopropoxide (TTIP). Then, the crystallized TiO2 was deposited with a simple yet low-cost spin-coat technique on flexible substrates (ITO/PET). A thorough scrutinization of TTIP concentration is crucial in identifying the potential of TiO2 films through comprehensive studies of elements aspects of structural, optical and electrical properties. The synthesized TiO2 films with a TTIP concentration of 0.5 M demonstrated a high porosity microstructure with exceptional transmittance, allowing a large number of photons to penetrate and thereby resulting in an enhanced charge carrier conduction mechanism. In addition, the direct optical bandgap is reduced with increasing TTIP molarity, proving the involvement of particle factors influencing photocatalytic activities. Moreover, electrical analysis proved that all the correlation features resulted in remarkably low sheet resistance and conductivity of 0.4 MΩ/sq and 0.1194 mS/cm, respectively. It can be conjectured from this study that the synthesis of crystallized TiO2 at low-temperature conditions with a certain TTIP molarity is successful and has resulted in an enhancement of the electron conduction mechanism, particularly for flexible emerging solar cell applications. Highlights: The TiO2 layer has been successfully synthesized by the sol-gel technique without the need for a subsequent conventional high-temperature annealing process, which enables the realization of fabrication for flexible emerging solar cells. A broad range of different titanium tetrapropoxide (TTIP) molarities have been optimized, resulting in sheet resistance comparable to conventional TiO2 layers subjected to a high annealing process. Furthermore, detailed studies from various aspects have also been critically analysed in terms of microstructure, optical and electrical properties to analyse the efficient charge carrier conduction mechanism. Last and foremost, sol-gel synthesized TiO2 with 0.5 M TTIP has shown remarkable features, paving the way for the fabrication of flexible PSC in the future. [ABSTRACT FROM AUTHOR]

In recent years, the power conversion efficiency (PCE (%)) of perovskite solar cells (PSCs) has improved to over 26%. To enhance the photovoltaic properties of PSCs, several materials for the electron transport layer (ETL) have been investigated. Zinc oxide (ZnO) is a significant ETL due to its high electron mobility and optical transparency in PSCs. As a result of various deposition methods, ZnO ETL can be processed at low temperatures. On the other hand, based on several studies, metal-doped ZnO can facilitate electron transfer, thereby improving the performance of un-doped ZnO ETL-based PSCs. Here, to improve the PCE (%) and long-term stability of un-doped ZnO ETL-PSCs, silver (Ag)-doped ZnO 1wt% as a buffer layer is examined. In this paper, with the addition of an organic solvent (ethanol) to the dispersion of Ag-doped ZnO 1 wt% nanoparticles (NPs) in deionized (DI) water, the morphology of the buffer layer (Ag-doped ZnO 1 wt%) can be controlled. This approach focuses on reducing the wettability of the ZnO/Ag-doped ZnO 1 wt% bilayer ETLs and enhancing the stability of un-doped ZnO ETL-PSCs. According to the results, the ZnO/H2O-ethanol mixtures-Ag-doped ZnO 1 wt% bilayer ETL leads to the formation of high-quality perovskite with low defects, reducing the recombination rate, and long-term stability of un-doped ZnO ETL-PSCs in ambient conditions. [ABSTRACT FROM AUTHOR]

Perovskite solar cells show great potential application prospects in the field of solar cells due to their promising properties. However, most perovskite solar cells that exhibit excellent photovoltaic performance typically require a carrier transport layer that necessitates a high-temperature annealing process. This greatly restricts the scalability and compatibility of perovskite solar cells in flexible electronics. In this paper, SnO2 nanoparticles with high crystallinity, good dispersibility and uniform particle size distribution are first prepared using a solvothermal method and dispersed in n-butanol solution. SnO2 electron transport layers are then prepared by a low-temperature spin coating method, and the photovoltaic characteristics of perovskite solar cells prepared with different SnO2 nanoparticles/n-butanol concentrations are studied. Results indicate that the rigid perovskite solar cell achieves the highest power conversion efficiency of 15.61% when the concentration of SnO2 nanoparticles/n-butanol is 15 mg mL-1. Finally, our strategy is successfully applying on flexible perovskite solar cells with a highest PCE of 14.75%. Our paper offers a new possibility for large-scale preparation and application of perovskite solar cells in flexible electronics in the future. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have garnered significant attention in the photovoltaic field owing to their exceptional photoelectric properties, including high light absorption, extensive carrier diffusion distance, and an adjustable band gap. Temperature is a crucial factor influencing both the preparation and performance of perovskite solar cells. The annealing temperature exerts a pronounced impact on the device structure, while the operational temperature influences carrier transport, perovskite band gap, and interface properties. This paper provides a comprehensive review of the influence of varied annealing temperatures on the hole transport layer, electron transport layer, and perovskite layer. Additionally, we present an overview of innovative annealing methods applied to perovskite materials. The effects of diverse working temperatures on the overall performance of perovskite cells are thoroughly examined and discussed in this review. In the end, different temperature conditions under ISOS testing conditions are summarized. [ABSTRACT FROM AUTHOR]

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.

Perovskite Solar Cells (PSCs) have managed to significantly capture attention by achieving efficiency values of 25.6% in a remarkably short period of around ten years. Each layer within the device plays a crucial role in the overall device efficiency when it comes to PSC production. PC61BM, a derivative of fullerene, is one of the most commonly used electron-transport layers (ETLs) in inverted-type PSCs. In this study, the improvement of the ETL was aimed by incorporating C60 into PC61BM, and the effects of the doped ETL on MAPbI3-based inverted-type PSCs were investigated. For inverted type PSCs which are fabricated under high humidity (40-60%) and room conditions (~25 °C), the power conversion efficiencies (PCEs) have boosted from 11.54% (for undoped PC61BM) to 13.40% (for C60-doped PC61BM). To comprehend the sources of improvement in the fabricated devices, a series of characterizations were carried out, including Current Density-Voltage (J-V), Hysteresis Factor (HF), Scanning Electron Microscope (SEM), and Atomic Force Microscope (AFM) measurements.

We developed inverted red quantum dot light-emitting diodes (QLEDs) with ZnO nanoparticles synthesized in open and closed systems. Wurtzite-structured ZnO nanoparticles were synthesized using potassium hydroxide and zinc acetate dihydrate at various temperatures in the open and closed systems. The particle size increases with increasing synthesis temperature. The ZnO nanoparticles synthesized at 50, 60, and 70 °C in the closed system have an average particle size of 3.2, 4.0, and 5.4 nm, respectively. The particle size is larger in the open system compared to the closed system as the methanol solvent evaporates during the synthesis process. The surface defect-induced emission in ZnO nanoparticles shifts to a longer wavelength and the emission intensity decreases as the synthesis temperature increases. The inverted red QLEDs were fabricated with a synthesized ZnO nanoparticle electron transport layer. The driving voltage of the inverted QLEDs decreases as the synthesis temperature increases. The current efficiency is higher in the inverted red QLEDs with the ZnO nanoparticles synthesized in the closed system compared to the devices with the nanoparticles synthesized in the open system. The device with the ZnO nanoparticles synthesized at 60 °C in the closed system exhibits the maximum current efficiency of 5.8 cd/A.

The electron transport layer plays a pivotal role in shaping the photovoltaic attributes of perovskite solar cells. SnO2 stands out as an exemplary electron transport layer for perovskite solar cells due to its exceptional carrier mobility, deep conduction band, suitable band gap, and compatibility with low-temperature processing. Although surface modification of SnO2 has yielded noteworthy enhancements in device performance over recent years, there remains considerable untapped potential to further refine its efficiency and long-term stability. In this study, thioacetamide was employed to modify the SnO2 surface, aiming to elevate the quality of the electron transport layer and establish a robust interface with perovskite. The findings underscored that the thioacetamide-modified SnO2 layer exhibited augmented perovskite absorption in the visible spectrum compared to the control sample. Additionally, the attenuation in photoluminescence intensity within the modified sample alludes to improved electron extraction and enhanced charge transport from the perovskite layer to the electron transport layer. Assessment of solar cell performance unveiled superior and more consistent photovoltaic parameters in the modified sample. Ultimately, the best efficiency was achieved with the perovskite solar cell using SnO2 modified with thioacetamide, boasting an efficiency of 15.15%

This work includes the numerical modeling (NM) of solar cells consisting of the active layer of CH3NH3SnI3 and electron transport layer of CdS, by employing a software SCAPS-1D. Organic-inorganic lead-based perovskites are superior in terms of power conversion efficiency. However, there are some serious drawbacks associated with them including poor stability, shorter life time and toxicity. Therefore, it is the demand of the hour to explore alternative materials to overcome these shortcomings. In this regard, tin is a competitive alternative to lead because it has similar electronic and chemical properties. Moreover, it is nontoxic, making it environmentally friendly. However, Sn based perovskite devices are reported with inferior power conversion efficacy, to date. In the present work, we have worked on a novel architecture of solar cells containing CH3NH3SnI3 as a light absorber layer and CdS as electron fetching layer. Optimization of the device was performed numerically by varying physical parameters related to the active layer such as thickness, defect density and shallow acceptor concentration. The proposed architecture of solar cells was proved as an efficient system with Jsc of 33.40 mA/cm2, Voc of 0.878 V, FF of 85.25 %, and PCE of 25.02 %. The temperature analysis has revealed that, temperature higher than 300 K increases the reverse saturation current, seriously degrading the structure of the device, hence limiting the power conversion performance of the solar cell. Furthermore, a rear electrode made of the high work function materials like Pt forms an ohmic junction at the HTL/anode interface, enhancing the performance of the device. Results of this study have paved the way for experimentalists to explore opportunities, to rationalize this architecture for real time applications such as inhouse lighting and laptop/smartphone charging.

The toxicity and stability concerns of lead based perovskite solar cells have limited the commercialization. The lead-free Cesium based double perovskite could be a viable answer to these issues. In this present work a theoretical analysis of Cesium based double perovskite solar cell using Spiro-OMeTAD as hole transport layer and effect of different ETLs such as SnO2, ZnO-NR, TiO2 and CdS has been studied. The optimized active layer thickness of 0.3 μm has been used and a device structure of FTO/ETLs/Cs2AgBiBr6/Spiro-OMeTAD/Cu was simulated. The Solar Cell Capacitance Simulator (SCAPS-1D) was used for one dimensional simulation and analysis. The maximum PCE of 5.62 % was found using SnO2 as ETL. The device performance has been optimized by employing various ETLs and the most suitable ETL for this structure was found to be SnO2. The maximum quantum efficiency of 86.09 % has been found for SnO2 electron transport layer. The simulation results obtained in this study are encouraging and will provide insightful guidance in replacing toxic Pb-based perovskite with eco-friendly inorganic perovskite solar cell. [ABSTRACT FROM AUTHOR]

Significant progress has been made in the advancement of perovskite solar cells, but their commercialization remains hindered by their lead-based toxicity. Many non-toxic perovskite-based solar cells have demonstrated potential, such as Cs2AgBi0.75Sb0.25Br6, but their power conversion efficiency is inadequate. To address this issue, some researchers are focusing on emerging acceptor–donor–acceptor'–donor–acceptor (A-DA'D-A)-type non-fullerene acceptors (NFAs) for Cs2AgBi0.75Sb0.25Br6 to find effective electron transport layers for high-performance photovoltaic responses with low voltage drops. In this comparative study, four novel A-DA'D-A-type NFAs, BT-LIC, BT-BIC, BT-L4F, and BT-BO-L4F, were used as electron transport layers (ETLs) for the proposed devices, FTO/PEDOT:PSS/Cs2AgBi0.75Sb0.25Br6/ETL/Au. Comprehensive simulations were conducted to optimize the devices. The simulations showed that all optimized devices exhibit photovoltaic responses, with the BT-BIC device having the highest power conversion efficiency (13.2%) and the BT-LIC device having the lowest (6.8%). The BT-BIC as an ETL provides fewer interfacial traps and better band alignment, enabling greater open-circuit voltage for efficient photovoltaic responses. [ABSTRACT FROM AUTHOR]

A high-quality tin oxide electron transport layer (ETL) is a key common factor to achieve high-performance perovskite solar cells (PSCs). However, the conventional annealing technique to prepare high-quality ETLs by continuous heating under near-equilibrium conditions requires high temperatures and a long fabrication time. Alternatively, we present a non-equilibrium, photoexcitation-induced passivation technique that uses multiple ultrashort laser pulses. The ultrafast photoexcitation and following electron–electron and electron–phonon scattering processes induce ultrafast annealing to efficiently passivate surface and bulk defects, and improve the crystallinity of SnO2, resulting in suppressing the carrier recombination and facilitating the charge transport between the ETL and perovskite interface. By rapidly scanning the laser beam, the annealing time is reduced to several minutes, which is much more efficient compared with conventional thermal annealing. To demonstrate the university and scalability of this technique, typical antisolvent and antisolvent-free processed hybrid organic–inorganic metal halide PSCs have been fabricated and achieved the power conversion efficiency (PCE) of 24.14% and 22.75% respectively, and a 12-square-centimeter module antisolvent-free processed perovskite solar module achieves a PCE of 20.26%, with significantly enhanced performance both in PCE and stability. This study establishes a new approach towards the commercialization of efficient low-temperature manufacturing of PSCs. [ABSTRACT FROM AUTHOR]

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.

A potential technology for converting clean and renewable energy is perovskite solar cells (PSCs). The electron transport layer (ETL), one of the vital parts of PSCs, is essential for improving device stability and efficiency. The relevance of indium sulfide (In2S3) as a superior material for ETL in PSCs is explored in this article. We analyzed the operation of PSCs and emphasized the value of ETLs in enabling effective charge extraction and minimizing recombination losses. In2S3 is a favorable nanomaterial for ETL applications due to its advantageous bandgap, excellent electron mobility, and chemical stability. Furthermore, the perovskite layer is shielded by In2S3's passivation properties, which also increase the stability of the device. A summary of recent developments in In2S3-based ETL research, including material engineering and deposition methods improvements, has been provided. The main view for the future is the possibility of improved In2S3 property optimization and interface engineering to improve PSC performance. Collaboration between scientists working on solar energy, devices, and materials will probably lead to new discoveries and test the limits of In2S3-based ETLs. Novel hybrid architectures and tandem arrangements provide exciting opportunities for better charge extraction with existing electron transport materials. The current investigation of In2S3-based ETLs in PSCs offers significant promise to revolutionize the solar energy sector, opening the path for sustainable and effective photovoltaic technology. However, stability, toxicity, and large-scale production issues must be addressed.

Perovskite solar cells are an attractive technology for renewable energy production. However, stability issues with the electron transport layer (ETL), particularly the colloidal tin oxide (SnO2) solution, can impact cell efficiency. In this study, a novel acidization treatment is introduced to reactivate long‐time stored SnO2 solutions, which previously led to low‐efficiency perovskite solar cells. The acidization treatment results in enhanced conductivity of the SnO2 layer, improved perovskite film quality, and ultimately increased efficiency. These findings show that a 1‐month stored SnO2 solution treated with acetic acid produces a device with a photoelectric conversion efficiency (PCE) of 20.9%, compared to 13.5% efficiency without treatment. With the addition of PEAI, the champion efficiency of the acetic acid‐treated device is 22.3%. This study provides a simple and effective engineering approach to fabricating high‐performance and stable ETLs for perovskite solar cells. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) electron transport layer (ETL) has been employed in inverted OSCs for highly efficient and stable devices. In this study, a Sn-doped ZnO layer was produced and employed in inverted OSCs based on the extensively used polymer, poly-3-hexylthiophene (P3HT). The performance of the reference device was enhanced from 1.01 to 3.45% by doping the ZnO layer with 3% Sn. The increased charge production, exciton dissociation, and better morphology, which led in an improved active layer/ETL interface, are the primaryleads to for the more than twofold PCE enhancement. Furthermore, after 3% Sn doping, the Voc of the reference device increased from 0.44 to 0.61 V due to a shift in the conduction band, which promotes charge transfer and minimizes energy loss in the device. The ETL's conductivity was increased by 7%, resulting in a considerable increase in photocurrent from 5.66 to 10.69 mA/cm2. As a result, Sn doping may be a promising low-cost technique to improve inverted OSC performance. [ABSTRACT FROM AUTHOR]

In recent years, perovskite solar cells (PSCs) have gained major attention as potentially useful photovoltaic technology due to their ever-increasing power-conversion efficiency (PCE). The efficiency of PSCs depends strongly on the type of materials selected as the electron transport layer (ETL). TiO2 is the most widely used electron transport material for the n-i-p structure of PSCs. Nevertheless, ZnO is a promising candidate owing to its high transparency, suitable energy band structure, and high electron mobility. In this investigation, hybrid mesoporous TiO2/ZnO ETL was fabricated for a perovskite solar cell composed of FTO-coated glass/compact TiO2/mesoporous ETL/FAPbI3/2D perovskite/Spiro-OMeTAD/Au. The influence of ZnO nanostructures with different percentage weight contents on the photovoltaic performance was investigated. It was found that the addition of ZnO had no significant effect on the surface topography, structure, and optical properties of the hybrid mesoporous electron-transport layer but strongly affected the electrical properties of PSCs. The best efficiency rate of 18.24% has been obtained for PSCs with 2 wt.% ZnO. [ABSTRACT FROM AUTHOR]