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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.

Recently, flexible perovskite solar cells (FPSCs) fabricated using solution-processed printing techniques have garnered significant attention. However, challenges remain in achieving cost-effective, scalable manufacturing under ambient conditions and ensuring stable, efficient devices. This study focuses on fabricating printed FPSCs using the slot-die coating technique and examines the impact of SnO2 quantum dot (QD) and (6,6)-Phenyl C61 butyric acid methyl ester (PCBM) based electron transport layers (ETLs) on device performance and hysteresis. Experimentally results show that SnO2 QD-based devices exhibited favorable photovoltaic properties but significant hysteresis compared to PCBM-based devices. Numerical simulations have shown that the hysteresis effect in devices is influenced not only by the higher concentration of mobile ions in the perovskite layer of PCBM-based devices compared to SnO2 QD-based devices, but also by the more effective redistribution of these ions during forward and reverse J-V scans. The results provide insights into the behavior of printed FPSCs with different ETLs, contributing to the development of high-performance, hysteresis-free printed FPSCs.

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.

Abstract 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 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 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 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.

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.

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 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.

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.

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.

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).

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 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.

In just a few years, the worldwide scientific community has worked diligently to increase the photovoltaic conversion efficiency of perovskite solar cells from 3.8% to 25.7%. Due to its low stability and poor scalability, it still lags in commercial performance concerning the crystalline silicon solar cell. Most of the high-efficiency perovskite solar cells (PSC) reported in the literature are on a 0.01 cm2 area, and the efficiency of PSC decreases with an increase in area. The maximum said stability to date is 10,000 h which is relatively low compared to crystalline silicon technology. This work discussed the causes of instability, degradation mechanism, scalable fabrication methods, and high-stability perovskite solar cell. It emphasised the need for setting up testing protocols for universal stability testing of perovskite solar cell technology. The study found that trap states in the absorber layer, hole transport layer (HTL), and electron transport layer (ETL) are the reason for lower stability. The lower dimension perovskite solar cell shows better stability compared to its 3D counterparts.

Abstract Tin oxide (SnO2) nano-crystalline thin films were deposited on silicon and glass substrates at room temperature by sputtering at a constant power of 30 W and different working pressure of 10, 7, and 5 mTorr. Surface morphology, electrical and optical properties of the films were investigated to optimise the deposition condition of the films as electron transport layer (ETL) for high-power conversion efficiency perovskite solar cells. The films were characterized by scanning electron microscopy (SEM), UV–Vis–NIR Spectrophotometer, and Four-point probe. SnO2 films obtained at working pressure of 10 mTorr exhibited uniform surface morphology with high light transmittance (90%) and conductivity (4 S/m). These sputtered SnO2 films appeared to have shown promising properties as ETL for PSC, and further investigation is justified to establish the optimal fabrication parameters and resulting energy conversion efficiency.

Magnetron sputtering technology benefits from an easy process parameter adjustment strategy, good experimental reproducibility, and high-quality film formation; thus, it is widely used in thin-film electronic devices. In the present work, the thickness and morphology of the TiO2 electron transport layer were controlled by magnetron sputtering time, and based on this technology, planar heterojunction perovskite solar cells were prepared. The results showed that with an increase in the sputtering time, the surface roughness of the TiO2 film decreased, and the electrical homogeneity and square resistance of the film increased. Especially, the film transmittance showed a maximum value of 82.29% at 45 min of deposition, and the so prepared perovskite solar cells exhibited the highest photoelectric conversion efficiency of up to 12.42%.

Perovskite solar cells could strongly compete with the silicon solar cells in the market soon as illustrated in recent studies. In this work, promising and stable metal-free perovskite solar cells (PSCs) has been successfully fabricated using an inorganic SnO2/Quantum dot SnO2 (QD-SnO2) double layer as an efficient electron transport layer via a low-temperature solution process. The fully-air fabricated PSCs in the form of FTO/SnO2/QD-SnO2/CH3NH3PbI3/Carbon were tested at different annealed QD-SnO2 between 300 and 500 °C. The as-prepared QD-SnO2 and the fabricated devices are characterized by various techniques, including XRD, XPS, HR-TEM, FE-SEM, UV–vis–NIR spectroscopy, PL, and solar simulator. The prepared QD-SnO2 at 300 °C has shown well-ordered nanoparticles of 5.6 nm in diameter with superior carrier density (1.5 × 1015 cm−3) and highest carrier mobility (64.1 cm2·V-1·s−1), accelerating the carriers separation process within the cell. The best devices demonstrated a maximum power conversion efficiency (PCE) of 11.7%, VOC 0.81 V, JSC 19.5 mA·cm−2, and FF 74%. The presence of an interfacial layer of QD-SnO2 over the blocking SnO2 upsurges the band gaps alignment and accelerates the carriers extraction rate affecting the performance of the fabricated perovskite devices. Moreover, the optimized fabricated devices revealed a shelf stability-life of four months in humid air (40%–50%) with >83% of its initial PCE. This simple synthetic approach can develop the opportunities to transfer the cell from the lab to the market, which will be compatible with large-scale production.

Abstract 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.

All-inorganic CsPbI3–xBrx perovskite solar cells (PSCs) are advantageous in terms of high thermal stability, while its efficiency lags behind those of organic-inorganic hybrid perovskite counterparts. Defect passivations have been extensively applied for enhancing efficiency of all-inorganic PSCs, which are mainly based on univocal defect passivation of perovskite layer. Herein, we incorporated a bis-dimethylamino-functionalized fullerene derivative (abbreviated as PCBDMAM) as an interlayer between ZnO electron transport layer (ETL) and all-inorganic CsPbI2.25Br0.75 perovskite layer, accomplishing synchronous defect passivations of both layers and consequently dramatic enhancements of efficiency and thermal stability of PSC devices. Upon spin-coating PCBDMAM onto ZnO ETL, the surface defects of ZnO especially oxygen vacancies can be effectively passivated due to the formation of Zn−N ionic bonds. In addition, PCBDMAM incorporation affords effective passivation of PbI and IPb antisite defects within the atop perovskite layer as well via coordination bonding with Pb2+. As a result, the regular-structure planar CsPbI2.25Br0.75 PSC device delivers a champion power conversion efficiency (PCE) of 17.04%, which surpasses that of the control device (15.44%). Moreover, the PCBDMAM-incorporated PSC device maintains ~ 80% of its initial PCE after 600 h heating at 85 °C hot plate in N2 atmosphere, whereas PCE of the control device degrades rapidly to ~ 62% after 460 h heating under identical conditions. Hence, PCBDMAM incorporation benefited dramatic improvement of the thermal stability of PSC device.

To enhance the overall performance of perovskite solar cells, the quality of the electron transport layer (ETL) held significant importance. Zinc oxide (ZnO) emerged as highly promising due to its exceptional optical and electrical characteristics. This study included the incorporation of lanthanum (La III) into the ZnO lattice to improve its optoelectronic properties. All the produced thin films were crystallized at low annealing temperatures. Through careful analysis, it was observed that the inclusion of doping with 4% La (III) resulted in increased crystallinity, leading to low surface roughness. Additionally, this doping strategy facilitated enhanced mobility of charge carriers and conductivity.

The power conversion efficiency (PCE) of thin-film solar cells (TFSCs) has drastically increased in the last few years. In this regard, perovskite solar cells (PSCs) come on the top thanks to their bandgap tunability, lower fabrication cost, and high absorption coefficient. In this work, a comprehensive simulation study is presented in which methylammonium-free PSCs are analyzed and designed. Also, the design of the presented solar cell structure is based on using a hole transport layer (HTL)-free. So, the design is carried out in such a way as to prevent the instability and cost issues associated with the organic materials, usually incorporated in HTLs, as well as methylammonium (MA) which limits the device operation stability. Next, the conduction band offset between the perovskite as an absorber and the electron transport layer (ETL) is controlled to provide a spike-like band offset that is more desirable by selecting appropriate materials serving as ETLs. The work function of the back contact is also investigated, and it is found that using Carbon, which has a lower cost than gold, is beneficial to get high efficiency. An enhanced performance has been achieved by combining the different steps of the design. This is reflected in the PCE which performs 25.35% instead of the initial calibrated cell which shows a PCE of 20.7%. The PCE could further be boosted to 27.8% if reduced absorber and interface defects are included. The calibration and simulation of the presented PSCs were done by utilizing SCAPS one-dimensional simulator, based on practical material parameters, at AM1.5 illumination.

Abstract This paper elucidates the increased luminescence efficiency of CsPbBr2.1Cl0.9 sky-blue perovskite light-emitting diodes (PeLEDs) achieved through the interface modification of 3,4 ethylenedioxythiophene (PEDOT):polystyrene sulfonic acid (PSS)/quasi-two-dimensional (QTD) perovskite using CsCl and CsBr materials, respectively. QTD films were fabricated using ratios of CsPbBr2.1Cl0.9 doped with phenethylamine hydrobromide (PEABr) at 60%, 80%, and 100%. The solvent dimethyl sulfide (C2H6OS) was employed under the excitation of ambient and 365-nm laser lights. The PeLED structure was composed of Al/LiF/2,2',2"-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi)/CsPbBr2.1Cl0.9:PEABr/interface modification layer/PEDOT:PSS/ITO glass. The optimized results revealed that the luminance, current efficiency, and external quantum efficiency of the QTD CsPbBr2.1Cl0.9:80% PEABr PeLED with the CsCl interface modification additive was 892 cd/m2, 3.87 cd/A, and 5.56%, respectively.

Significant advances in the performance of organic photovoltaic (OPV) devices can facilitate their use in internet of things applications. However, achieving excellent photostability and high efficiency using stable, efficient OPV devices in indoor settings is considerably difficult. To address this issue, a zinc oxide (ZnO) electron transport layer (ETL) was modified with a self-assembled monolayer of 4-aminobenzoic acid (ABA) in the present study, and the impact of this modification was correlated with the indoor performance of an OPV device with the PM6:L8-BO photoactive layer. The ABA-treated ZnO ETL exhibited a significant reduction in the work function (from 4.51 to 4.04 eV), surface roughness (from 0.201 to 0.177 nm), and hydrophilicity of an indium-tin-oxide electrode; this aided in selectively extracting charge carriers from the device and minimizing trap-assisted recombination losses. Additionally, the ABA treatment of the ZnO ETL considerably enhanced the electron mobility and recombination resistance. It reduced the trap density, thereby enabling the ZnO/ABA-based device to achieve improved performance. Consequently, the ZnO/ABA-based device exhibited a noteworthy 14.68% higher maximum power output than that of the device without any ZnO surface modification under 1000 lx halogen (HLG) illumination ( P _out, max = 354.48 and 309 µ A cm ^−2 , respectively). Moreover, under thermal illumination conditions (1000 lx HLG lighting), the ZnO/ABA-based device sustained ∼74% of its initial power conversion efficiency over 120 h, significantly higher than its ABA-free equivalent (∼55%).

Abstract Tin oxide has made a major breakthrough in high‐efficiency perovskite solar cells (PSCs) as an efficient electron transport layer by the low‐temperature chemical bath deposition method. However, tin oxide often contains pernicious defects, resulting in unsatisfactory performance. Herein, we develop high‐quality tin oxide films via a nitrogen‐doping strategy for high‐efficiency and stable planar PSCs. The aligned energy level at the interface of doped SnO2/perovskite, more excellent charge extraction and reduced nonradiative recombination contribute to the enhanced efficiency and stability. Correspondingly, the power conversion efficiency of the devices based on N‐SnO2 film increases to 23.41% from 20.55% of the devices based on the pristine SnO2. The N‐SnO2 devices show an outstanding stability retaining 97.8% of the initial efficiency after steady‐state output at a maximum power point for 600 s under standard AM1.5G continuous illumination without encapsulation, while less than 50% efficiency remains for the devices based on pristine SnO2. This simple scalable strategy has shown great promise toward highly efficient and stable PSCs.

We demonstrate the high efficiency of quantum dot light-emitting diodes (QLEDs) that consist of a mixed layer of SnO2 nanoparticles (NPs) and quantum dots (QDs). A stable mixture of SnO2 NPs and QDs is prepared in chlorobenzene and then applied to QLEDs with no separate electron transport layer (ETL). QLEDs with such a simplified structure produce a maximum luminance of 142,855 cd/m2, an EQE of 9.42%, and a current efficiency of 41.18 cd/A that result from the improved charge balance of the mixed layer. This produces one of the best device performances of QLEDs with a non-ZnO inorganic ETL, clearly indicating the remarkable promise of using SnO2 NPs as an inorganic ETL for QLEDs. Moreover, the reduction of fabrication steps in this solution-based process proves advantageous to next-generation display technology.

The methyl ammonium tin iodide (Ch3Nh3SnI3) perovskite nanocrystals have attracted research interest and have become a rising star in the horizon of photovoltaics due to its narrow band gap, wide visible absorption coefficient and environmental friendliness than its lead-based counterpart (Ch3Nh3PbI3) . In this article, a tin based perovskite solar cell with Zinc oxide (ZnO) and Copper Oxide (CuO) as electron transport medium (ETM) and hole transport medium (HTM) was proposed and investigated numerically using a Solar Cell Capacitance Simulator (SCAPS) tool. With appropriate parameters, a short-circuit current density (Jsc) of 27.56 mA/cm2, open-circuit voltage (Voc) of 0.82 V, fill factor (FF) of 59.32 %, and power conversion efficiency (PCE) of 13.41 % are obtained for the initial simulation. By varying the thicknesses of the absorber and electron transport layer, the optimum thicknesses were observed at 0.6 um and 0.3 um for Ch3Nh3SnI3 and ZnO with corresponding PCEs of 14.36 % and 13.42 %. Upon simulation with optimized parameters, a Jsc of 29. 71 mA/cm2, Voc of 0.83 V, FF of 61.23 % and PCE of 15. 10 % were recorded. These values are superior to those obtained without optimization which means that solar cell performance can be improved to some extent by adjusting the perovskite and electron transport layer and also, Ch3Nh3SnI3 Perovskite solar cell (PSC) is a potential environmentally friendly solar cell with considerable efficiency.

Tin (IV) oxide is a highly promising electron transport layer (ETL) for lead halide perovskite solar cells due to its high conductivity, transparency, wide band gap, and the possibility of low-temperature processing. Nonetheless, charge carrier recombination processes at the SnO2/perovskite interface diminish the device performance. Here, we demonstrate that SnO2 doping with guanidine hydrochloride (G-SnO2) leads to efficient surface passivation and a larger band offset between the ETL and the perovskite layer, resulting in reduced voltage losses and faster electron transfer. Moreover, G-SnO2 facilitates the growth of highly crystalline perovskite layers. Consequently, a power conversion efficiency of up to 23.48% and a high open-circuit voltage of 1.18 V are obtained in solar cells incorporating the G-SnO2 ETL. These devices also exhibited negligible hysteresis and maintained more than 96% of their initial power conversion efficiency after 1,250 h exposure to the air without encapsulation.

In this work, the use of poly [(9,9-bis (30- (N,N-dimethylamino) propyl) -2,7-fluorene) -alt-2,7- (9,9-dioctylfluorene) (PFN) as electron transport layer (ETL) in inverted small molecule solar cells (SM-iOSCs) is analyzed. The optical and electrical characteristics obtained are compared with those obtained for similar SM-iOSCs where the ETL was zinc oxide. The p-DTS(FBTTh2)2 and PC70BM materials are used as donor and acceptor in the bulk heterojunction active layer, respectively for all devices. The photovoltaic devices exhibited a power conversion efficiency of 6.75% under 1 sun illumination. Impedance measurements were used to understand the causes that dominate the performance of the devices. We found that the loss resistance is governed by the PFN layer, which results in a lower fill factor value. Studies of atomic force microscopy, external quantum efficiency, and absorption UV-vis on the active layer have been performed to understand the effects of the charge transport dynamics on the performance of the devices.

Improving morphological and electronic properties of the electron transport layer (ETL) is a critical issue to fabricate highly efficient perovskite solar cells. Tin dioxide is used as an ETL for its peculiarities such as low-temperature solution-process and high electron mobility and several handlings have been tested to increase its performances. Herein, SnO2:ZnO and SnO2:In2O3 composites are studied as ETL in planar n-i-p CH3NH3PbI3 solar cells fabricated in ambient air, starting from glass/ITO substrates. Morphological, electrical and optical properties of zinc- and indium-oxide nanoparticles (NPs) are investigated. First-principle calculations are also reported and help to further explain the experimental evidences. Photovoltaic performances of full devices show an improvement in efficiency for SnO2:In2O3–based solar cells with respect to pristine SnO2, probably due to a suppression of interfacial charge recombination between ITO/ETL and ETL/perovskite. Moreover, a better homogeneity of SnO2:In2O3 deposition with respect to SnO2:ZnO composites, conducts an increase in perovskite grain size and, consequently, the device performances.

Abstract Suitable electron transport materials bearing good interfacial contact, improved electron transport ability, and matched energy levels are indispensable for developing efficient perovskite solar cells (PSCs). Herein, regular (n‐i‐p) planar Cs0.05FA0.83MA0.12PbI2.55Br0.45 (CsFAMA) PSC devices were fabricated using a pyridine‐functionalized fullerene derivative (C60‐3‐BPy) as an independent electron transport layer (ETL), delivering a decent power conversion efficiency (PCE) of 18.22%, which is dramatically higher than that of the control device based on [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) ETL (15.70%). The energy level offset between C60‐3‐BPy and the perovskite is smaller than that based on PCBM ETL, which is beneficial for efficient ohmic contact in ETL/perovskite interface and improved open‐circuit voltage (Voc). Moreover, C60‐3‐BPy affords strong coordination interactions with perovskite, leading to an improved film quality of the perovskite layer with enlarged grain size and decreased trap state density, which contribute to facilitated electron extraction as reflected by the increases of both the fill factor (FF) and the short‐circuit current (Jsc). C60‐3‐BPy‐facilitated electron extraction further results in hysteresis‐free devices.

SnO2 nanorods were grown on two kinds of seed layers formed from SnCl2·2H2O and SnO2 nanoparticles precursors, respectively, and used as one-dimensional electron transport materials to fabricate perovskite solar cell (PSCs). Effects of the seed layers on morphology, structure, optical properties of SnO2 nanorods and perovskite films, charge transfer at SnO2/perovskite interfaces as well as device performance were investigated by utilizing field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible-near infrared spectroscopy(UV-vis), steady-state photoluminescence spectroscopy (PL) and volt-ampere characteristic curves (J-V). The results show that more dense seed layers can be formed from SnO2 nanoparticles and SnO2 nanorods films formed from SnO2 nanoparticles are more smooth and uniform relative to those grown from SnCl2·2H2O. The perovskite films deposited on the former show better crystallization quality and higher light absorption. The maximum efficiency of the device based on the SnO2 nanorods is 12.93%. This work demonstrates that SnO2 nanoparticles are a kind of excellent seed layer material for growing SnO2 nanorods films, and lays foundation for the preparation of high-performance perovskite solar cells based on one-dimensional electron transport materials.

In recent years, the perovskite solar cells have gained much attention because of their ever-increasing power conversion efficiency (PCE), simple solution fabrication process, flyable, light-weight wearable and deployable for ultra-lightweight space and low-cost materials constituents etc. Over the last few years, the efficiency of perovskite solar cells has surpassed 25% due to high-quality perovskite-film accomplished through low-temperature synthesis techniques along with developing suitable interface and electrode-materials. Besides, the stability of perovskite solar cells has attracted much well-deserved attention. In this article we have focused on recent progress of the perovskite solar cells regarding their crystallinity, morphology and synthesis techniques. Also, demonstrated different layers such as electron transport-layers (ETLs), hole transport-layers (HTLs) and buffer-layers utilized in perovskite solar-cells, considering their band gap, carrier mobility, transmittance etc. Outlook of various tin (Sn), carbon and polymer-based perovskite solar cells and their potential of commercialization feasibility has also been discussed.

Organic-inorganic halide perovskite thin film perovskite solar cells are gaining much attention, in recent years. Designing proper electron transport layer (ETL) and hole transport layer (HTL) with high quality to achieve devices with higher efficiency are fundamental. One dimensional (1D) nanostructures are newly introduced materials with high mobility and low recombination rate, which may improve the device performance. In this paper, 1D ZnO nanorods (ZnO-NRs) as well as planar TiO2 are considered as the ETL of the device and their electrical performance are compared with different HTL materials in Sn- and Pb- perovskite. In addition, impact of critical design parameters including absorber thickness, interface defect density, back contact electrode materials on the performance of the device are comprehensively assessed. In this work, the simulations have been carries out using a 1D Solar Cell Capacitance Simulator (SCAPS-1D). The results show that in Sn- perovskite, ZnO-NRs has superior performance in comparison with TiO2 with maximum photon conversion efficiency (PCE) of 16.7 % and short circuit current density of 30.21(mA/cm2). However, in terms of Pb-perovskite planar TiO2 has given the best performance with PCE of 19.6%. The results in this paper pave the way for introducing inexpensive high performance solar cell.

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.

Tin dioxide (SnO2) has recently been recognized as an excellent electron transport layer (ETL) for perovskite solar cells (PSCs) due to its advantageous properties, such as its high electron mobility, suitable energy band alignment, simple low-temperature process, and good chemical stability. In this work, nitrogen-doped graphene quantum dots (N-GQDs) were prepared using a hydrothermal method and then used to fabricate N-GQD:SnO2 nanocomposite ultrathin films. N-GQD:SnO2 nanocomposite ultrathin films were investigated and applied as electron transport layers in planar PSCs. The presence of N-GQDs with an average size of 6.2 nm in the nanocomposite improved its morphology and reduced surface defects. The excitation–emission contour map indicated that the N-GQDs exhibited a remarkably enhanced light-harvesting capability due to the possibility of absorbing UV light and producing emissions in the visible range. The quenching of photoluminescence spectra showed that the N-GQDs in nanocomposite ultrathin films improved electron extraction and reduced charge recombination. As a result, the power conversion efficiency (PCE) of our planar PSCs fabricated with the optimized N-GQD:SnO2 nanocomposite electron transport layer was improved by 20.4% over pristine SnO2-based devices.

Abstract Efficient electron transport layers (ETLs) not only play a crucial role in promoting carrier separation and electron extraction in perovskite solar cells (PSCs) but also significantly affect the process of nucleation and growth of the perovskite layer. Herein, crystalline polymeric carbon nitrides (cPCN) are introduced to regulate the electronic properties of SnO2 nanocrystals, resulting in cPCN-composited SnO2 (SnO2-cPCN) ETLs with enhanced charge transport and perovskite layers with decreased grain boundaries. Firstly, SnO2-cPCN ETLs show three times higher electron mobility than pristine SnO2 while offering better energy level alignment with the perovskite layer. The SnO2-cPCN ETLs with decreased wettability endow the perovskite films with higher crystallinity by retarding the crystallization rate. In the end, the power conversion efficiency (PCE) of planar PSCs can be boosted to 23.17% with negligible hysteresis and a steady-state efficiency output of 21.98%, which is one of the highest PCEs for PSCs with modified SnO2 ETLs. SnO2-cPCN based devices also showed higher stability than pristine SnO2, maintaining 88% of the initial PCE after 2000 h of storage in the ambient environment (with controlled RH of 30% ± 5%) without encapsulation.

The present study evaluates the effects of ZnO nanorods electron transport layer morphology synthesized using the low temperature chemical bath method on the performance of organic solar cells. The photoactive layers consisted of P3HT as electron donor and PCBM as electron acceptor. Two ZnO nanorods electron transport layers were studied, one with a smooth surface and a decorated surface. Well-defined ZnO nanorods with perfect hexagonal shapes could be synthesized by chemical bath deposition. Structural characterization confirmed that the vertically aligned ZnO nanorods were successfully obtained in pure form. Performance analysis revealed that the use of decorated ZnO nanorods increased the overall performance relative to the uncoated ZnO nanorods, attributed to the possible increase of light paths on the ZnO nanorods. The best device was obtained from annealed decorated ZnO nanorods ETL having PCE of 7.38%, Voc of 0.63 V, Jsc 18.44 mAcm−2 and FF of 0.60. Solar cells made from decorated ZnO nanorods ETL presented high Rsh of 1311.67 Ω.cm2 and 1497.23 Ωcm2 for as-synthesized and annealed ZnO ETL, respectively. In general, the strategy of decorating ZnO nanorods ETL is an important strategy to fabricate highly efficient organic solar cells and thus may have good potential for many other organic solar cells comprising other polymers apart from P3HT. Even though the efficiency obtained is low compared to the PCE achieved so far, this study gives the observation that may be possibly useful in the further improving PCE of already achieved high efficiencies.

Electron transport layer (ETL), one of the important layers for high-performing perovskite solar cells (PSCs), also has great potential in bioengineering applications. It could be used for biological sensors, biological imaging, and biomedical treatments with high resolution or efficiency. Seldom research focused on the development of biological material for ETL and their application in biological uses. This review will introduce commercial and biological materials used in ETL to help readers understand the working mechanism of ETL. And the ways to prepare ETL at low temperatures will also be introduced to improve the performance of ETL. Then this review summarizes the latest research on material doping, material modification, and bilayer ETL structures to improve the electronic transmission capacity of ETLs. Finally, the application of ETLs in bioengineering will be also shown to demonstrate that ETLs and their used material have a high potential for biological applications.

Research about mesoporous TiO2 as an electron transport layer in perovskite solar cell has been done to obtain the best fabricated cell’s performance. In this research, the concentrations of opaque and transparent TiO2 nanoparticle were varied, in order to optimize the TiO2 mesoporous electron transport layer in FTO/CL-TiO2/MS-TiO2/Perovskite/P3HT/Ag perovskite-based solar cell. Morphological, optical, and electrical characteristics of TiO2 layers were investigated using scanning electron microscopy (SEM), four-point probe (FPP), and UV-Vis spectroscopy. The influences of those characteristics in solar cell performance were analyzed by using illumination of sun simulator with a light intensity of 500 W/m2. The results showed that transparent TiO2 has a higher conductivity and transmittance compared to the opaque TiO2. The concentration of TiO2 solutionin1:17 ratio resulted in higher electrical performance in both the transparent and opaque TiO2 layer. The best perovskite solar cell performance with PCE of 0.37% was achieved from the sample using TiO2 transparent layer with a concentration of 1:7 ratio.

Abstract A high‐quality electron transport layer (ETL) is a critical component for the realization of high‐efficiency perovskite solar cells. We developed a controllable direct‐contact reaction process to prepare a chlorinated SnO2 (SnO2‐Cl) ETL. It is unique in that (a) 1′2‐dichlorobenzene is used to provide more reactive Cl radicals for more in‐depth passivation; (b) it does not introduce any impurities other than chlorine. It is found that the chlorine modification significantly improves the electron extraction. Consequently, its associated solar cell efficiency is increased from 17.01% to 17.81% comparing to the pristine SnO2 ETL without the modification. The hysteresis index is significantly reduced to 0.017 for the SnO2‐Cl ETL.