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The electron transport layer (ETL) is critical in perovskite solar cells (PSCs) as it controls the optics of the complete solar cell. This study uses an industrially viable RF magnetron sputtering technique to prepare the tungsten oxide (WOx) ETL for PSCs. Necessary morphological and optoelectronic investigations were carried out to ensure the high-quality WOx thin-film. The influence of the deposition power on the ETL thickness and PSC optics were systematically investigated. A three-dimensional (3D) finite-difference time-domain (FDTD) approach analyses the optics and optimization of the complete solar cell. The investigations allow the optimized planar PSC to determine the JSC of > 21 mA/cm2. The optical performance of the planar device is limited due to higher optical losses; hence, the current study proposes a PSC design embedded with Ag nanoparticles. The proposed PSC can improve the JSC by ~ 17% (up to 24.5 mA/cm2) than the planar device owing to improved light trapping, further boosting the PSC's energy conversion efficiency (ECE). A detailed discussion on film realization and solar cell optics is provided. [ABSTRACT FROM AUTHOR]

The race towards modern photovoltaic devices necessitates the development of more efficient and stable perovskite solar cells (PSC) at reliable cost. Metal oxides are exploited as better materials for electron and hole transport in PSCs. ZnO has emerged as a better substitute for the TiO2 electron transport layer (ETL) owing to its higher electron mobility, low cost, simple synthesis methodologies and low annealing temperature which facilitates its application on flexible substrates. Most high-performance PSCs using ZnO ETL employ various organic hole transport layers (HTL) such as spiro-OMeTAD, which are high cost, unstable and involves complex fabrication processes. Metal oxide HTLs are commonly fabricated as p type HTL of ZnO-based inverted p-i-n structures of PSC. Cu2O has emerged as a p-type layer for various p-i-n configurations using ETLs such as TiO2 and phenyl c-61 butyric acid methyl ester (PCBM). The application of metal oxides such as Cu2O as the p type top HTL of PSC is considered as complex in fabrication. The work focusses on the fabrication of Cu2O and NiO as the top layer for ZnO n-i-p planar configuration, fluorine-doped tin oxide (FTO)/ZnO/CH3NH3PbI3/Cu2O/Au and (FTO)/ZnO/CH3NH3PbI3/NiO/Au. Moreover, the metal oxides are synthesized by a simple solution synthesis process and used in their pure form without any doping or surface treatments. Different layers were grown using spin coating at room temperature. The fabricated n-i-p structure, FTO/ZnO/CH3NH3PbI3/Cu2O/Au exhibited a stable power conversion efficiency of 6.02% with Jsc of 12 mA/cm2, Voc of 0.76 V and fill factor of 0.63. The performance of this structure was compared with the second structure which showed a power conversion efficiency of 5.02%. Cu2O thus proves to be a reliable inorganic HTL that can be employed for ZnO n-i-p planar configuration. [ABSTRACT FROM AUTHOR]

Tin oxide (SnO2) is broadly used as an electron transport layer (ETL) in organic solar cells (OSCs). However, there are many hydroxyl groups and the defects of oxygen vacancy on the surface of SnO2, resulting in charge recombination. Herein, an electrolyte 4‐(dimethyl(pyridin‐2‐yl) ammonio)butane‐1‐sulfonate (PAS) is doped into SnO2 films with an appropriate proportion to improve the performance of the inverted OSCs. The PAS can coordinate with the Sn atoms in SnO2 films to reduce the surface defects, resulting adjustable work function and increased electron conductivity. Meanwhile, the PAS doping can decrease the surface energy of SnO2 layer, forming vertical phase distribution of the active layer for better exciton dissociation and charge transport. The PM6:Y6 based inverted OSC with SnO2 ETL shows a power conversion efficiency (PCE) of 14.72%, while the device with PAS‐doped SnO2 ETL demonstrates greatly enhanced PCE of 16.37%. The device performance can be further improved by using PM6:BTP‐eC9 as active layer and a PCE of 17.12% can be achieved with PAS‐doped SnO2 ETL. Furthermore, PAS‐doped SnO2 can effectively enhance the device stability under continuous illumination. These findings demonstrate that exquisite regulation of SnO2 layer via a small electrolyte molecule coordination is a promising approach to achieve efficient and stable inverted OSCs. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) based nanoparticles (NPs) are the most commonly used electron transport layer (ETL) materials in quantum dot light‐emitting diodes (QLEDs). However, numerous defects, severe quenching, and poor stability of ZnO NPs limit the commercialization of QLEDs. Herein, tin oxide (SnO2) NPs are prepared as a substitute to ZnO. The obtained SnO2 NPs exhibit high conductivity, good transparency, and excellent stability, thus enabling them to be applied as multifunctional ETLs for various structured QLEDs, e.g., 1) as a phase tuning layer to tune the microcavity effect in inverted QLEDs, 2) as a thick protection layer to improve the stability of noninverted QLEDs, 3) as a sputtering buffer layer to protect the functional layers from the ion bombardment damage in transparent QLEDs, and 4) as an internal light extraction layer to enhance the light coupling efficiency of top‐emitting QLEDs. With the multifunctional SnO2 ETL, the resultant QLEDs are highly efficient (external quantum efficiency of 27.6%) and stable (half lifetime of 323 h at 4,459 cd m−2), which are comparable and even better than ZnMgO based devices. The results suggest that SnO2 is a promising ETL material for realizing efficient and stable QLEDs. [ABSTRACT FROM AUTHOR]

[Display omitted] Perovskite solar cells (PSCs) have become a promising photovoltaic (PV) technology. Meanwhile, developing an electron transport layer (ETL) has been an effective way to promote the power conversion efficiency (PCE) of PSCs. Here, a 4-morpholine ethane sulfonic acid sodium salt (MES Na+) doped SnO 2 ETL is utilized in planar heterojunction PSCs. The results show that the MES Na+ doped ETL can improve the crystallinity, and absorbance of perovskite films, and passivate interface defects between the perovskite film and SnO 2 ETL. The doping effect accounts for the enhancement of conductivity and the decreasing work function of SnO 2. When 10 mg mL−1 MES Na+ was added to the SnO 2 precursor solution, the device showed the best performance Jsc, Voc, and FF of the PSCs values, which were 23.88 mA cm−2, 1.12 V and 78.69%, respectively, and the PCE was increased from 17.43% to 21.05%. This doping ETL strategy provides an avenue for defect passivation to further increase the efficiency of perovskite solar cells. [ABSTRACT FROM AUTHOR]

Fluorine and indium elements in F‐doped SnO2 (FTO) and Sn‐doped In2O3 (ITO), respectively, significantly contribute toward enhancing the electrical conductivity of these transparent conductive oxides. In this study, fluorine was combined with indium to modify the SnO2 electron transport layer (ETL) through InF3. Consequently, the modified perovskite solar cells (PSCs) showe the favorable alignment of energy levels, improved absorption and utilization of light, enhanced interfacial charge extraction, and suppressed interfacial charge recombination. After InF3 modification, the open circuit voltage (Voc) and fill factor (FF) of the PSC were significantly improved, and the photoelectric conversion efficiency (PCE) reached 21.39 %, far exceeding that of the control PSC (19.62 %). [ABSTRACT FROM AUTHOR]

[Display omitted] • Effects of KCl treatment on SnO 2 ETL and perovskite absorber were investigated. • KCl treatment modified conduction band minimum and Fermi energy so as to improve band alignment between ETL and perovskite absorber. • By the KCl treatment, K + ion diffused into absorber and passivated defects both at perovskite/ETL interface and in bulk perovskite. • Admittance spectroscopy firstly showed direct evidence of the defect passivation via the diffused K + ion. • Due to better band alignment and defect passivation, J-V hysteresis was diminished in the KCl-treated cell. SnO 2 has been studied intensively as an electron transport layer (ETL) for highly efficient metal halide perovskite solar cells. However, SnO 2 ETL frequently exhibits defect-related issues associated with the bulk SnO 2 and the perovskite/SnO 2 interface, and to passivate the defect states potassium ion has been used. In order to investigate the passivation effect of potassium ion, we carried out KCl treatment on the solution-processed SnO 2 ETL. It was found that KCl-treatment shifted up conduction band maximum and Fermi energy of SnO 2 , and reduced the band gap of perovskite absorber by K+ diffusion, which resulted in a better conduction band alignment at perovskite/SnO 2. Admittance spectroscopy revealed that diffused K+ ions can passivate defects of the perovskite absorber layer. With the improvement of band alignment and defect passivation via the KCl treatment, the J-V hysteresis was almost eliminated and power conversion efficiency was much enhanced with improved open-circuit voltage and fill factor. [ABSTRACT FROM AUTHOR]

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.

Compositional engineering is considered one of the recent interesting techniques used in the field of perovskite solar cells (PSCs). In this method, more than one material was used in a specific cation in the perovskite structure. This work aims to simulate the cesium-containing triple-cation perovskite (TCP) via the SCAPS-1D simulation program with a device structure of ITO/SnO2/TCP/Spiro-OMeTAD/Au. First, we studied the effect of interface defects on the PCSs with respect to experimental results and found that when no interface defects occur, the power conversion efficiency (PCE) reaches a value of 22.16% which is higher than the reported PCE, implying that the fabricated cell suffers from the interface defects as a main effect on cell degradation. Incorporating interface defects into the simulation results in a very good match between the experimental and simulated data with a PCE of 17.92%. Further, to provide possible routes to enhance the performance of the solar cell under investigation, impacts of absorber layer thickness, conduction band offset (CBO), surface recombination velocity, and light intensity were explored. In addition, hole transport layer (HTL)-free design was investigated to alleviate the instability issues associated to the organic HTL, leading to a PCE of 18.28%, for a surface velocity of 104 cm/s, which is interestingly higher than the initial cell. The provided study reveals the critical role of interface defects and other key design factors and suggests potential solutions to alleviate the subsequent degradation mechanisms, thereby enhancing the overall cell performance.

In the realm of photovoltaic research, 2D transition metal carbides (MXenes) have gained significant interest due to their exceptional photoelectric capabilities. However, the instability of MXenes due to oxidation has a direct impact on their practical applications. In this work, the oxidation process of Nb 2 CT x MXene in aqueous systems is methodically simulated at the atomic level and nanosecond timescales, which elucidates the structural variations influenced by the synergistic effects of water and dissolved oxygen, predicting a transition from metal to semiconductor with 44% C atoms replaced by O atoms in Nb 2 CT x . Moreover, Nb 2 CT x with varying oxidation degrees is utilized as electron transport layers (ETLs) in perovskite solar cells (PSCs). Favorable energy level alignments with superior electron transfer capability are achieved by controlled oxidation. By further exploring the composites of Nb 2 CT x to its derivatives, the strong interaction of the nano-composites is demonstrated to be more effective for electron transport, thus the corresponding PSC achieves a better performance with long-term stability compared with the widely used ETLs like SnO 2 . This work unravels the oxidation dynamics of Nb 2 CT x and provides a promising approach to designing ETL by exploiting MXenes to their derivatives for photovoltaic technologies., (© 2024 Wiley‐VCH GmbH.)

Inverted organic solar cells (OSCs) have garnered significant interest due to their remarkable stability. In this study, the efficiency and stability of inverted OSCs are enhanced via the in situ self-organization (SO) of an interfacial modification material Phen-NaDPO onto tin oxide (SnO 2 ). During the device fabrication, Phen-NaDPO is spin-coated with the active materials all together on SnO 2 . Driven by the interactions with SnO 2 and the thermodynamic forces due to its high surface energy and the convection flow, Phen-NaDPO spontaneously migrates to the SnO 2 interface, resulting in the formation of an in situ modification layer on SnO 2 . This self-organization of Phen-NaDPO not only effectively reduces the work function of SnO 2 , but also enhances the ordered molecular stacking and manipulates the vertical morphology of the active layer, which suppress the surface trap-assisted recombination and minimize the charge extraction. As a result, the SO devices based on PM6:Y6 exhibit significantly improved photovoltaic performance with an enhanced power conversion efficiency of 17.62%. Moreover, the stability of the SO device is also improved. Furthermore, the SO ternary devices based on PM6:D18:L8-BO achieved an impressive PCE of 18.87%, standing as one of the highest values for single-junction inverted organic solar cells to date., (© 2024 Wiley‐VCH GmbH.)

We fabricated MAPbI 3 perovskite thin films with ZnO on a glass substrate, in which a passivation layer (Phenethylammonium iodide (PEAI); p-methoxyphenethylammonium iodide (CH 3 O-PEAI); 2-methoxyethylammonium iodide (MEAI)) was inserted between two layers. In order to understand the effect of the insertion of each passivation material on the transfer efficiency of the photo-generated electrons from MAPbI 3 to ZnO, we observed the near-field heterodyne transient grating (NF-HD-TG) responses of each film and investigated the component arising from the recombination of the trapped electrons at the ZnO surface. Based on the accelerated recombination between photo-generated holes remaining in the MAPbI 3 layer and surface-trapped electrons in ZnO and the increase in the number of the trapped electrons in ZnO when either CH 3 O-PEAI or PEAI was applied, we successfully revealed that the charge transfer efficiency was enhanced by the insertion of the passivation materials including a benzene ring stabilizing the defect states. Particularly, it was demonstrated that CH 3 O-PEAI showed the highest increase in the charge transfer efficiency, which could be attributed to the high electron density in the benzene ring, resulting from the existence of the electron donating group, CH 3 O, and its role in the effective transition from 3D to 2D perovskite phases., (© 2024 The Author(s). ChemPhysChem published by Wiley-VCH GmbH.)

The efficacy of electron transport layers (ETLs) is pivotal for optimizing the device performance of perovskite photovoltaic applications. However, colloidal dispersions of SnO 2 are prone to aggregation and possess structural defects, such as terminal-hydroxyls (OH T ) and oxygen vacancies (V O s), which can degrade the quality of ETLs, impede charge extraction and transport, and affect the nucleation and growth processes of the perovskite layer. In this study, the Sb(OH) 4 - ions hydrolyzed from SbCl 3 in colloidal dispersion can bind to defect sites and effectively stabilize the SnO 2 nanocrystals are demonstrated. Upon oxidative annealing, a Sb 2 O 5 @SnO 2 composite film is formed, in which the Sb 2 O 5 not only mitigates the aforementioned defects but also broadens the energy range of unoccupied states through its dispersed conduction band. The increased electron affinity (EA) facilitates more efficient capture of photoexcited electrons from the perovskite layer, thus augmenting electron extraction and minimizing electron-hole recombination. As a result, a significant improvement in power conversion efficiency (PCE) from 22.60% to 24.54% is achieved, with an open circuit voltage (V OC ) of up to 1.195 V, along with excellent stability of unsealed devices under various conditions. This study provides valuable insights for the understanding and design of ETLs in perovskite photovoltaic applications., (© 2024 Wiley‐VCH GmbH.)

Simplifying the manufacturing processes of multilayered high-performance perovskite solar cells (PSCs) is yet of vital importance for their cost-effective production. Herein, an in situ blending strategy is presented for co-deposition of electron transport layer (ETL) and perovskite absorber by incorporating (3-(7-butyl-1,3,6,8-tetraoxo-3,6,7,8-tetrahydrobenzo- [lmn][3,8]phenanthrolin-2(1H)-yl)propyl)phosphonic acid (NDP) into the perovskite precursor solutions. The phosphonic acid-like anchoring group coupled with its large molecular size drives the migration of NDP toward indium tin oxide (ITO) surface to form a distinct ETL during perovskite film forming. This strategy circumvents the critical wetting issue and simultaneously improves the interfacial charge collection efficiencies. Consequently, n-i-p PSCs based on in situ blended NDP achieve a champion power conversion efficiency (PCE) of 24.01%, which is one of the highest values for PSCs using organic ETLs. This performance is notably higher than that of ETL-free (21.19%) and independently spin-coated (21.42%) counterparts. More encouragingly, the in situ blending strategy dramatically enhances the device stability under harsh conditions by retaining over 90% of initial efficiencies after 250 h in 100 °C or 65% humidity storage. Moreover, this strategy is universally adaptable to various perovskite compositions, device architectures, and electron transport materials (ETMs), showing great potential for applications in diverse optoelectronic devices., (© 2024 Wiley‐VCH GmbH.)

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 (TiO 2 ) 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 TiO 2 and the perovskite layer, thus improving the adhesion of the perovskite to the TiO 2 ETL through strong bonding of the ─CF 3 and ─SO 3 - 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 TiO 2 . The unencapsulated device maintained 81.3% of its initial PCE after operating for 1000 h., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

The electron transport layer (ETL) plays a critical role in efficient and stable perovskite solar cells (PSCs). The current effective method for the large-scale preparation of metal oxide ETLs is mainly based on expensive sputtering processes. Here, a screen-assisted self-spreading method is proposed as a novel approach to prepare uniformly thin and conformal TiO 2 films on a rough fluorine-doped tin oxide (FTO) substrate as an ETL in planar PSCs. The TiO 2 ETL deposited by this method exhibited good coverage and homogeneity on the rough FTO substrate, thereby minimizing interfacial recombination. The photovoltaic performance of the PSCs fabricated by this method is superior to that of the cells fabricated by spin coating, especially in terms of the fill factor. The performance enhancement can be attributed to the complete coverage of the FTO substrate by the conformal TiO 2 film, confirming the effectiveness and reliability of the proposed method for the preparation of the TiO 2 ETL. The advantages of this method lie in its scalability to prepare oxide films with a large area, eliminating the requirement of complex equipment, such as spinners, sputters, or physical vapor deposition equipment.

In recent years, carbon-based materials, particularly carbon nanotubes (CNTs), have gained intensive research attention in the fabrication of organic solar cells (OSCs) due to their outstanding physicochemical properties, low-cost, environmental friendliness and the natural abundance of carbon. In this regard, the low sheet resistance and high optical transmittance of CNTs enables their application as alternative anodes to the widely used indium tin oxide (ITO), which is toxic, expensive and scarce. Also, the synergy between the large specific surface area and high electrical conductivity of CNTs provides both large donor-acceptor interfaces and conductive interpenetrating networks for exciton dissociation and charge carrier transport. Furthermore, the facile tunability of the energy levels of CNTs provides proper energy level alignment between the active layer and electrodes for effective extraction and transportation of charge carriers. In addition, the hydrophobic nature and high thermal conductivity of CNTs enables them to form protective layers that improve the moisture and thermal stability of OSCs, thereby prolonging the devices’ lifetime. Recently, the introduction of CNTs into OSCs produced a substantial increase in efficiency from ∼0.68 to above 14.00%. Thus, further optimization of the optoelectronic properties of CNTs can conceivably help OSCs to compete with silicon solar cells that have been commercialized. Therefore, this study presents the recent breakthroughs in efficiency and stability of OSCs, achieved mainly over 2018–2021 by incorporating CNTs into electrodes, active layers and charge transport layers. The challenges, advantages and recommendations for the fabrication of low-cost, highly efficient and sustainable next-generation OSCs are also discussed, to open up avenues for commercialization.

Efficient organic photovoltaics (OPV) based on SnO2 | perylene diimide (PDI) bilayer as an electron transport layer (ETL) is fabricated and tested in an ambient environment. The PTQ10:Y6 photoactive system is used as the primary bulk‐heterojunction. Without any surface treatment, the power conversion efficiency (PCE) of SnO2‐based OPV devices is 1.5%. Treating the SnO2 nano‐particles with UV‐ozone and then applying a layer of N‐annulated PDI with a functional NH bond (PDIN‐H) on top increase device PCEs to 9.2%. For indoor applications, the OPV device PCE rises from 8.1% to 12.3% when PDIN‐H is employed on SnO2 and tested under low light conditions, without the need for light soaking. The SnO2 | PDIN‐H ETL bilayer is slot‐die coated and corresponding OPV devices have a PCE of 7.9%, demonstrating utility for OPV scale‐up. The hybrid ETL is tested with other photoactive systems employing Y6, Y7, and IDIC as acceptors, as well as PM6 donor, and all these cases yield OPV devices with improved PCE when compared to OPV devices with SnO2‐only ETLs. These results show the successful implementation of SnO2 | PDIN‐H as an ETL for OPV. [ABSTRACT FROM AUTHOR]

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 FROM AUTHOR]

High conductivity and transparency of the electron-transporting layer (ETL) is essential to achieve high efficiency perovskite solar cells (PvSCs). Generally, titanium dioxide (TiO2) has been extensively utilized as an ETL in PvSCs. Both surface roughness and uniformity of the compact-TiO2 (C-TiO2) can influence the efficiency of the PvSC. This work investigates the optimization of the direct current (DC) sputtering power and the ratio of argon (Ar) to oxygen (O2) plasma to achieve high quality ETL films. The effect of changing the DC sputtering power on the C-TiO2 films and subsequently on the overall efficiency was studied. The electrical and optical properties of the C-TiO2 layer were characterized for various DC powers and different ratios of Ar to O2 plasma. It was found that the optimum preparation conditions for the C-TiO2 films were obtained when the DC power was set at 200 W and a flow rate of 6 sccm Ar and 12 sccm O2. A power conversion efficiency (PCE) of 15.3% in forward sweep and 16.7% in reverse sweep were achieved under sunlight simulator of 100 mW/cm2. These results indicate that significant improvement in the efficiency can be achieved, by optimizing the C-TiO2 layer. [ABSTRACT FROM AUTHOR]

Summary: Herein, ferroelectric Ti‐doped BiFeO3 (BFTO) heterojunction photovoltaic (PV) cells are realized for underwater PV applications. In the heterostructure, NiO functions as a transparent wide‐bandgap (3.2 eV) hole transport layer (HTL), whereas BFTO is the visible energy harvester and the highly conductive WS2 behaves as the electron transport layer (ETL). The multijunction PV device with a cell area of 1cm2 revealed a current density (JSC) and an open‐circuit voltage (VOC) of 1.90 mA/cm2 and 1.20 V, respectively, under ambient conditions (before submerging into water). Subsequently, the polydimethylsiloxane (PDMS)‐encapsulated Ag/NiO/BFTO/WS2/ITO PV device was investigated for underwater solar energy harvesting in a shallow tank. For a comparative analysis, the mono‐junction NiO/BFTO and BFTO/WS2 PVs were also evaluated. The results indicated a steady decrease in the efficacy and power density of the cell with depth, and the heterojunction PV has outperformed the single‐junction PVs. As there are spectral variations with increase in depth, the heterostructure seem to have the potential to absorb the overall spectrum as NiO being transparent transmits high energy UV radiations into the device, while BFTO and WS2 layers absorb the visible and NIR spectrum. Therefore, the device though submerged can capture the solar energy efficiently with minimal losses in terms of spectrum and function efficiently. These results establish that the ferroelectric nano‐heterostructured PV devices can be utilized as a power generating source for various low‐power marine‐based sensing applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Interfacial engineering for passivating perovskite surface defects and reducing nonradiative recombination loss has been proven to be an effective strategy to fabricate highly efficient and stable perovskite solar cells (PSCs). However, the detailed understanding of the original role of interface materials on the charge‐carriers transfer dynamics of electron transport layer (ETL) remains lacking. Herein, a perylene diimide (PDI) was engineered onto perovskite surfaces to afford passivation of undercoordinated surface defects, which correlates this with the improvement of photovoltaic performance and stability of PSCs. Extensively experimental and theoretical studies reveal that PDI molecule can effectively modulate the surface properties of perovskite film through not only interaction of carbonyl groups in PDI with surface defects but also formation of close‐packed superstructure of PDI onto perovskite surfaces. Consequently, the PDI‐treated PSCs exhibits an increase of power conversion efficiency from 19.52% to 22.24% with an excellent stable device maintaining 95% of its initial value for 900 h in ~45% relative humidity. Importantly, transient absorption spectroscopic measurements further provide an evidence for the origin of the improved photovoltaic performance in PDI‐treated PSCs device, in which the modulation of PDI enhanced the electron transfer across ETL interface more efficiently. Our study provides new insights to understand the effect of interfacial material on the charge‐carrier transfer dynamics in PSCs device.

Towards commercialization of perovskite solar cells (PSCs), further reducing the cost and increasing the stability of PSCs have been the most important tasks of researchers, as the efficiency of single-junction PSCs has reached a competitive level among all kinds of single-junction solar cells. Carbon-electrode-based PSCs (CPSCs), as one of the most promising constructions for achieving stable economical PSCs, now attract enormous attention for their cost-effectiveness and stability. Here, we briefly review the development of CPSCs and reveal the importance of n-i-p architecture for state-of-the-art CPSCs. However, despite their promising potential, challenges still exist in CPSCs in the n-i-p architecture, which mainly stem from the incompact contact of the hole-transporting layer (HTL)/carbon electrode. Thus, new carbon materials and/or novel manufacturing methods should be proposed. In addition, HTL is yet to be appropriate for state-of-the-art CPSCs because the fabrication of carbon electrode could result in the destruction of the underlayer. To further enhance the performance of CPSCs, both the HTL and electron transport layer as well as their interfaces with perovskite active layer need to be improved. We recommend that the perovskite active layer, with its long carrier lifetime, strong carrier transport capability, and long-term stability, is necessary as well for improved performance of CPSCs. We also highlight current researches on CPSCs and provide a systematic review of various types of regulation tools.

The electron transport layer (ETL) has been extensively investigated as one of the important components to construct high-performance perovskite solar cells (PSCs). Among them, inorganic semiconducting metal oxides such as titanium dioxide (TiO2), and tin oxide (SnO2) present great advantages in both fabrication and efficiency. However, the surface defects and uniformity are still concerns for high performance devices. Here, we demonstrated a bilayer ETL architecture PSC in which the ETL is composed of a chemical-bath-deposition-based TiO2 thin layer and a spin-coating-based SnO2 thin layer. Such a bilayer-structure ETL can not only produce a larger grain size of PSCs, but also provide a higher current density and a reduced hysteresis. Compared to the mono-ETL PCSs with a low efficiency of 16.16%, the bilayer ETL device features a higher efficiency of 17.64%, accomplished with an open-circuit voltage of 1.041 V, short-circuit current density of 22.58 mA/cm2, and a filling factor of 75.0%, respectively. These results highlight the unique potential of TiO2/SnO2 combined bilayer ETL architecture, paving a new way to fabricate high-performance and low-hysteresis PSCs.

Solar cells based on lead-free perovskite have demonstrated great potential for next-generation renewable energy. The SCAPS-1D simulation software was used in this study to perform novel device modelling of a lead-free perovskite solar cell of the architecture ITO/WS2/CH3NH3SnI3/P3HT/Au. For the performance evaluation, an optimization process of the different parameters such as thickness, bandgap, doping concentration, etc., was conducted. Extensive optimization of the thickness and doping density of the absorber and electron transport layer resulted in a maximum power-conversion efficiency of 33.46% for our designed solar cell. Because of the short diffusion length and higher defect density in thicker perovskite, an absorber thickness of 1.2 µm is recommended for optimal solar cell performance. Therefore, we expect that our findings will pave the way for the development of lead-free and highly effective perovskite solar cells.

Even though Fe2O3 is reported as the electron-transporting layer (ETL) in perovskite solar cells (PSCs), its fabrication and defects limit its performance. Herein, we report a Fe2O3 ETL prepared from FeCl3 solution with a dopant Fe3O4 nanoparticle modification. It is found that the mixed solution can reduce the defects and enhance the performance of Fe2O3 ETL, contributing to improved electron transfer and suppressed charge recombination. Consequently, the best efficiency is improved by more than 118% for the optimized device. The stability efficiency of the Fe2O3-ETL-based device is nearly 200% higher than that of the TiO2-ETL-based device after 7 days measurement under a 300 W Xe lamp. This work provides a facile method to fabricate environmentally friendly, high-quality Fe2O3 ETL for perovskite photovoltaic devices and provides a guide for defect passivation research.

Recently, the simulation of perovskite solar cells (PSCs) via SCAPS-1D has been widely reported. In this study, we adopted SCAPS-1D as a simulation tool for the numerical simulation of lead-free (Pb-free) PSCs. We used methyl ammonium germanium iodide (MAGeI3) as a light absorber, zinc oxysulphide (ZnOS) as an electron transport layer (ETL), and spiro-OMeTAD as a hole transport layer. Further, the thickness of the ZnOS, MAGeI3, and spiro-OMeTAD layers was optimized. The optimal thicknesses of the ZnOS, MAGeI3, and spiro-OMeTAD layers were found to be 100 nm, 550 nm, and 100 nm, respectively. The optimized MAGeI3-based PSCs exhibited excellent power conversion efficiency (PCE) of 21.62%, fill factor (FF) of 84.05%, and Jsc of 14.51 mA/cm2. A fantastic open circuit voltage of 1.77 V was also obtained using SCAPS-1D. We believe that these theoretically optimized parameters and conditions may help improve the experimental efficiency of MAGeI3-based PSCs in the future.

The high performance of perovskite solar cells was produced with the help of an electron transport layer (ETL) and hole transport layer. The film ETL (mesoporous (meso)-TiO2/carbon dot) boosted the efficiency of the perovskite solar cells. A perovskite cell was fabricated by a coating of carbon dot on a meso-TiO2 ETL. The fabricated meso-TiO2/carbon dot-based device has decreased the pin-holes of the perovskite film layer compared to the meso-TiO2-based device, which boosted 3% of the averaged PCE value of the devices. The UV–visible spectroscopy confirmed that the meso-TiO2/carbon dot ETL showed better absorbance, that is, absorbed more incident light than meso-TiO2 ETL to generate higher power conversion efficiency. Coating of carbon dot on meso-TiO2 reduced carrier recombination, and fadeaway of the perovskite film cracks. The X-ray diffraction spectra displayed the removal of the perovskite component after spin-coating of carbon dot to the meso-TiO2 ETL, indicating that the suppression of non-radiative recombination improves the device performance compared to meso-TiO2 ETL. The stability after four weeks on the performance of the device was improved to be 92% by depositing carbon dot on meso-TiO2 ETL compared to the meso-TiO2 ETL-based device (82%). Thus, the high-quality perovskite cell was fabricated by coating carbon dot on a meso-TiO2 ETL, because the electron transport between ETL and perovskite film layer was improved by the injection of electrons from carbon dot.

A hybrid tin-based perovskite solar cell with p-i-n inverted structure is modeled and simulated using SCAPS. The inverted structure is composed of PEDOT:PSS (as hole transport layer—HTL)/GA0.2FA0.78SnI3-1% EDAI2 (as perovskite absorber layer)/C60-fullerene (as electron transport layer—ETL). Previous experimental studies showed that unlike conventional tin-based perovskite solar cells (PSC), the present hybrid tin-based PSC passes all harsh standard tests and generates a power conversion efficiency of only 8.3%. Despite the high stability that this material exhibits, emphasis on enhancing its power conversion efficiency (PCE) is crucial. To that end, various ETL and HTL materials have been rigorously investigated. The impact of energy level alignment between HTL/absorber and absorber/ETL interfaces have been elucidated. Moreover, the thickness and the doping concentration of all the previously mentioned layers have been varied to inspect their effect on the photovoltaic performance of the PSC. The optimized structure with CuI (copper iodide) as HTL and ZnOS (zinc oxysulphide) as ETL scored a PCE of 26%, which is more than three times greater than the efficiency of the initial structure. The current numerical simulation on GA0.2FA0.78SnI3-1% EDAI2 could greatly increase its chance for commercial development.

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As a promising photovoltaic technology, perovskite solar cells (pero-SCs) have developed rapidly over the past few years and the highest power conversion efficiency is beyond 25%. Nowadays, the planar structure is universally popular in pero-SCs due to the simple processing technology and low-temperature preparation. Electron transport layer (ETL) is verified to play a vital role in the device performance of planar pero-SCs. Particularly, the metal oxide (MO) ETL with low-cost, superb versatility, and excellent optoelectronic properties has been widely studied. This review mainly focuses on recent developments in the use of low-temperature-processed MO ETLs for planar pero-SCs. The optical and electronic properties of widely used MO materials of TiO2, ZnO, and SnO2, as well as the optimizations of these MO ETLs are briefly introduced. The commonly used methods for depositing MO ETLs are also discussed. Then, the applications of different MO ETLs on pero-SCs are reviewed. Finally, the challenge and future research of MO-based ETLs toward practical application of efficient planar pero-SCs are proposed. [ABSTRACT FROM AUTHOR]

In this paper, we report the amorphous Ge NPs film which is fabricated at room-temperature by PECVD method. The uniform, compact and smooth film is formed by orderly packing of the Ge NPs in the longitudinal direction, resulting in the formation of columnar structures in the Ge NPs film. The electrical, optical properties and energy levels of the Ge NPs film meet the requirements of the OSCs for ETL, and the PTB7:PC 70 BM OSCs with the Ge NPs ETL shows the PCE of 7.38%. [Display omitted] • The amorphous Ge NPs film is fabricated by using the PECVD method at room temperature. • The compact and orderly packing of the NPs in the longitudinal direction leads to the formation of columnar structures in the Ge NPs film. • The electrical, optical properties and energy levels of the Ge NPs film meet the requirements of the OSCs for ETL. • The PTB7:PC 70 BM OSCs with the Ge NPs ETL shows the PCE of 7.38%. The performances of the organic solar cells (OSCs) largely depends on the selection and preparation of the electron transport layer (ETL). In this paper, the uniform and compact Ge nanoparticles (NPs) film was fabricated by using the plasma enhanced chemical vapor deposition (PECVD) method at room temperature. The Ge NPs film is formed by close packing of amorphous Ge particles with an average diameter of 6.05 nm, and the film shows a fairly smooth surface with a root-mean-square (RMS) roughness of 0.6419 nm. The results shows that Ge NPs film exhibits n-type characteristics, and the longitudinal conductivity of the film is 1.90 × 10−5 S/cm, which is better than that of the ZnO NPs film. The excellent longitudinal charge transport characteristics is attributed to the existence of the columnar structures in the Ge NPs. In addition, the Ge NPs film shows a visible light transmittance comparable to that of the ZnO NPs film. More importantly, the energy levels of the Ge NPs film meets the requirements of the PTB7:PC 70 BM OSCs for the ETL, and the devices with the Ge NPs ETL shows the power conversion efficiency (PCE) of 7.38%. The characteristic of room temperature preparation make the Ge NPs ETL may become a reliable choice for the flexible devices in the near future. [ABSTRACT FROM AUTHOR]

• Ozone treated ZnO surface analysed in term of crystallinity, and structure by SEM and XRD. • Charge transport in ozone treated ZnO surface studied by ultrafast transient absorption spectroscopy. • Comparison of the electrical parameter of the organic solar cell under different ozone treatment time. • Defect state and its impact on performance of organic solar cell identified using capacitance spectroscopy. Zinc oxide (ZnO) has great potential as an electron transport layer (ETL) for producing efficient and stable organic solar cells. The effect of ozone treatment on ZnO working as the ETL in the organic solar cell has been studied by analyzing crystallinity, the defect density of states, and charge carrier dynamics from transient absorption spectroscopy to understand its role in the improvement in the interface between ETL and active layers. We have observed that a 10-minute continuous ozone treatment of ZnO film demonstrates improvement in its crystallinity leading to a 23% increment in short circuit current. The improvement in the crystallinity has been confirmed by the morphological and structural analysis using SEM and GIXRD. These analyses reveal the formation of a flake-like structure and an increase in peak intensity in GIXRD. It has been observed that ozone exposure has significantly affected the carrier recombination resistance, ideality factor of the device. From transient absorption spectroscopy, it has been found that for 10 min ozone-treated ZnO film has an average carrier transport time (661.79 ps), which is smallest as compared to untreated film or over treated film leading to faster carrier extraction through ETL. Further, the study of defect density of states shows that optimized ozone-treated film show 22.08% decrease in defects as compared to the control device, which primarily reflected as the improvement in the current density leading to increase in device efficiency from 2.95% to 3.75%. [ABSTRACT FROM AUTHOR]

Interface engineering has been demonstrated to be effective in suppressing the defect‐related carrier recombination loss and optimizing the energy level between SnO2 electron transport layer and mixed‐cation perovskite to further improve the performance of perovskite solar cells (PSCs). Herein, a versatile organic salt, trigonelline hydrochloride (TH), is selected to modify the SnO2/perovskite interface. TH molecule plays a multifunctional role at the interface: (1) COOH and pyridine cation can passivate the interface defects by esterification and electrostatic interaction, respectively. (2) Cl− plays a vital part in the improvement of perovskite crystallization. (3) Dipole effect can move the energy level of SnO2 resulting in optimized band alignment to more efficient electron extraction. The effects of TH at the interface are revealed by density functional theory calculations, surface chemical analyses, and energy level investigations. As a consequence, the PSCs with TH‐modified SnO2 (SnO2‐TH) exhibit best power conversion efficiency of 21.23%, compared to 19.59% for the reference devices, which mainly results from an enhanced open‐circuit voltage (Voc) from 1.098 V to 1.145 V. Moreover, the humidity stability of the non‐encapsulated devices is also significantly improved after introducing TH to the interface. [ABSTRACT FROM AUTHOR]

[6, 6]-phenyl C 61 butyric acid methyl ester (PC 61 BM) is a common fullerene derivative widely employed as an electron transport layer in inverted perovskite solar cells. However, major challenges such as interfacial recombination, current leakage and low mobility results in poor photovoltaic performance and stability for PC 61 BM-based devices. To overcome these issues, we demonstrated, for the first time, doping of the PC 61 BM with fullerene C 60 to tailor the properties of the PC 61 BM. This doping approach helped to realize superior power conversion efficiency of perovskite solar cell with 17.46% versus pristine device with 14.20%. The C 60 doped PC 61 BM reinforced the surface morphology of the PC 61 BM layer with reduced roughness and better coverage, up-shift of Fermi Level, higher electrical conductivity, higher maximum charge carrier generation rate, and higher charge collection probability. All these improvements contributed to reduced charge leakage at the interface, reduced charge recombination and promoted efficient charge transfer, transport, and collection. Furthermore, the enhanced hydrophobicity of the C 60 doped PC 61 BM enabled superior ambient device stability compared to the pristine device. This work facilitates a simple and effective route to tailor perovskite solar cell performance towards higher efficiency and better stability. [Display omitted] • Doping C 60 into PC 61 BM ETL is a promising route to enhance PSCs performance. • Doping C 60 into PC 61 BM improved the film surface morphology of the PC 61 BM ETL. • Charge leakage at the interface, and charge recombination were decreased. • Electrical conductivity, charge generation, and charge collection were increased. • PC 61 BM:C 60 ETL increased efficiency of PSC by 23% and exhibited superior stability. [ABSTRACT FROM AUTHOR]

With the aim of balancing charge carriers in the active region, we investigated a double electron transporting layer with the size control of zinc oxide nanoparticles. Here, we present cadmium‐free quantum dot light‐emitting diodes that enhance the stability by 5.9 times through preventing spontaneous electron injection compared to references. [ABSTRACT FROM AUTHOR]

[Display omitted] • The introduction of potassium bitartrate (KBT) into the TiO 2 film improves TiO 2 surface smoothness and charge transport, reducing recombination centers in PSCs. • KBT in TiO 2 ETLs enhances PSC morphology, reduces interface defects, and improves energy alignment, leading to higher efficiency and stability. • PSCs with KBT show a significant efficiency increase to 23.35 % and maintain over 80 % efficiency after 800 h. The performance of perovskite solar cells (PSCs) has rapidly improved, largely due to advancements in mitigating inherent defects and enhancing interface carrier transport properties. Herein, we provide a facile method to improve the morphology of TiO 2 ETLs, suppress defects at interface, and tailor energy level alignment to enhance carrier separation and extraction efficiency by introducing potassium bitartrate (KBT) into the TiO 2 electron transport layers (ETLs), achieving high-efficiency and stable PSCs. KBT molecules can enhance the surface smoothness of TiO 2 ETLs, resulting in denser and more uniform perovskite films. In addition, the carboxyl groups, hydroxyl groups, and potassium cations containing in KBT improve charge transport efficiency at TiO 2 /perovskite interface by reducing non-radiative recombination centers in TiO 2 and perovskite bottom as well as improving energy level matching. As a result, the target PSC exhibits an obvious improvement in performance with a champion efficiency of 23.35 %, which is greatly improved relative to the control (21.66 %). The long-term operational stability is also remarkably enhanced, after 800 h MPPT, PSCs with KBT remain over 80 % of its initial efficiency. PSCs with KBT-doped ETLs exhibit increased efficiency and stability, highlighting potential of KBT as an interface engineering tool for enhancing PSCs performance. [ABSTRACT FROM AUTHOR]

The lead-free (Pb-free) perovskite solar cell draws a significant interest in the current photovoltaic (PV) technology due to their substantial improvement in efficiency and their better environmental compatibility. This study uses the computational methods for the efficient identification of optimal ETL and HTL materials without the need for extensive experimental trials. The numerical study of the manganese (Mn)-based ([NH3-(CH2)2-NH3]MnCl4) perovskite solar cell using the one-dimensional solar cell capacitance simulator SCAPS 1D is performed. SCAPS is considered due to its proven accuracy and reliability in simulating the performance of perovskite solar cells, providing detailed insights into device behavior. The optimization of the charge transport layers is accomplished by interrelating the built-in potential (Vbi) with the open-circuit voltage (VOC) which in turn exhibits a direct relationship between them. It is concluded from the simulation analysis that the ECB_ETL-EVB_HTL, ΦFC-EVB_HTL, ΦBC-ECB_ETL, and Vbi indicate a significant impact on the device performance. It is also obtained from a simulation study that to attain a high-performance solar cell, a barrierless interface formation is an essential condition. In the current simulation analysis, the ZnTe and CuAlO2 are considered as optimized HTL, whereas for the ETL, ZnSnN2 is considered which enhances the PCE up to 27.43% which is considered a significant improvement in the Pb-free Mn-based single-junction perovskite solar cell. These findings unlock a new opportunity for further development of Pb-free perovskite solar cells (PSC). [ABSTRACT FROM AUTHOR]

[Display omitted] • Atomic-level precision SnO 2 thin films were grown by a pulsed laser deposition (ALD) method. • The ALD conditions were fine-tuned to examine their effects on film properties. • The carrier concentration and Fermi level tended to increase with increasing the growth temperature, while the surface roughness and oxygen content showed the reverse trend. • PSCs with SnO 2 ETLs grown at various ALD conditions were fabricated and tested. • A PSC with a 15 nm-thick SnO 2 ETL grown at 200 °C showed the best cell performance. The electron transport layer (ETL) of a perovskite solar cell (PSC) plays a pivotal role in determining cell performance. In this work, an atomic layer deposition (ALD) technique was employed to grow high-quality SnO 2 thin films, and those ALD-grown SnO 2 films were used as ETLs of PSCs. The properties of films and the performance of PSCs were closely examined depending on the SnO 2 growth conditions. The SnO 2 films grown at higher temperatures showed a very small surface roughness (≤0.6 nm) though grown faster. The relative oxygen content of the film was inclined to decrease with increasing the growth temperature. Consequently, the carrier concentration and the Fermi level of the film became higher at elevated temperatures. PSCs with ALD-grown SnO 2 ETLs also revealed a clear correlation between cell performance and the film growth temperature. The results of this work may offer practical guidelines for enhancing the performace of a PSC that employs a metal oxide as an ETL. [ABSTRACT FROM AUTHOR]

In semi-transparent perovskite solar cells (PSCs) comprising a sputtered top electrode, the minimisation of detrimental sputter damage and/or its curing by post-processing treatment is essential to reach high efficiencies. In this work, we investigate the influence of sputter damage and post-deposition annealing steps for different electron transport layers (ETLs) in PSCs without the need of a protective buffer layer such as tin oxide deposited by atomic layer deposition. We compare solution-processed 6,6-Phenyl C61 butyric acid methyl ester (PCBM) to thermally evaporated C 60 , each in combination with a bathocuproine (BCP) layer deposited by spin coating or thermal evaporation including a thickness variation. In general, we find that C 60 is more resilient against sputter damage and thus C 60 -based cells show higher as-grown power conversion efficiencies (PCEs). Post-deposition annealing of the complete cell stack increases the PCE further to values > 16 % on 0.5 cm2 active area. However, we observe that the remaining solvent in the spin-coated PCBM layer is highly beneficial for the curing of the sputter damage during post-deposition annealing and we achieve even higher PCEs for cells incorporating solution-processed PCBM with up to > 18 % on 0.5 cm2. We show an alternative way to reach high efficiency semi-transparent perovskite solar cells without using thermally evaporated C 60 and/or a buffer layer like tin oxide deposited by atomic layer deposition (ALD). • Semi-transparent perovskite solar cells with PCE >18 % on 0.5 cm2 active area and a absorber bandgap of 1.63 eV. • No protective buffer layer like ALD-SnOx between ETL and sputtered TCO. • Curing of sputter damage with a short post-deposition annealing step at 90 °C. • Small residues of solvent in PCBM layer are detected by ToF-SIMS and are of great importance for the curing of sputter damage. • Investigating the influence of the ETL deposition method on as-grown efficiencies and post-deposition annealing behaviour. [ABSTRACT FROM AUTHOR]

TiO 2 is one of the most widely explored materials as an electron transport layer (ETL) in dye sensitized solar cells (DSSCs) due to its excellent physical and chemical properties. However, recombination at the device's interface slackens the charge carrier movement, adversely affecting their device performance. Rapid extraction of photogenerated charge carriers plays a vital role in developing high efficiency DSSCs. The conduction band alignment of TiO 2 ETL and N719 dye light absorber plays a crucial role in charge carrier dynamics of DSSCs. Herein, the band structure of TiO 2 ETL is finely tuned by the incorporation of cesium bromide (CsBr). At the optimal concentration (0.4 Wt. %), DSSCs achieved the best power conversion efficiency (PCE) of 9.28 % compared to 7.61 % for pristine TiO 2. The modified TiO 2 –CsBr ETL induced a negative shift in flat band potential (V f b) from −0.46 to −0.50 V, which improved the open circuit voltage (V OC), its work function (ɸ) from −4.71 to −3.75 eV and increased conduction band minimum (CBM) from −3.58 to −2.42 eV. CsBr incorporation increased electron density in TiO 2 matrix, indicating the suppression of trap state and significantly improved the overall photovoltaic performance of DSSCs. • DSSC fabricated with TiO 2 –CsBr (0.4 Wt.%) electron transport layer achieved the best power conversion efficiency of 9.28 %. • The modified TiO 2 –CsBr induced a faster electron transport and shifting flat band potential (V f b) from −0.46 to −0.50V. • After modification the work function (ɸ) of TiO 2 reduced from −4.71 to −3.75eV. [ABSTRACT FROM AUTHOR]

[Display omitted] • Organic solar cells (OSCs) are great for internet of things because these work with versatility and can be used both indoors and outdoors. • Inverted configuration makes OSCs more stable and efficient than the conventional one. • Successful exploration of ZnO and Ga-doped ZnO based electron transport layer (ETL) for improved light harvesting by inverted OSC. • Fine-tuned doping concentration in ZnO yield 10.96 % and 4.95 % power conversion efficiency under 1-sun and 1000 lx halogen. • Ga-doping in ZnO improves the photostability of OSC by decreasing oxygen vacancies and retarding its formation under sustained light exposure. Organic solar cells (OSCs) are gaining attention for powering Internet of Things devices due to their impressive power conversion efficiency, flexibility, and slim designs suitable for both indoor and outdoor. The focus on inverted-structured OSCs is increasing due to their superior stability compared to conventional OSCs. This study investigates the use of inverted OSCs with electron transport layers (ETL) made from ZnO and Ga-doped ZnO for light harvesting. OSCs were fabricated using PM6:ITIC-4F as the active layer, and the impact of ZnO doping (Ga) concentration was examined under 1-sun and 1000 lx halogen. Optimizing the doping concentration significantly improved device performance, with PCE values of 10.96 % and 4.95 % for optimally doped ZnO under 1-sun conditions and halogen lamps, respectively. A comparison of photostability under 1-sun and 1000 lx halogen, with varying light soaking durations (0–240 min), showed that Ga-doping in the ZnO ETL improved photostability by reducing oxygen vacancies and slowing down their formation during continuous light exposure. This decrease in oxygen vacancies and enhancement of grain boundaries positively affected charge transport, leading to higher PCE. In summary, Ga-doped ZnO ETL in inverted OSCs demonstrates improved performance and photostability, making them promising for various light harvesting applications. [ABSTRACT FROM AUTHOR]

Interest in perovskite solar cell (PSC) research is increasing because PSC has a remarkable power conversion efficiency (PCE), which has notably risen to 28.3 %. However, commercialization of PSCs faces a significant obstacle due to their stability issues. This review article primarily focuses on several key aspects of PSCs, including different types of solar cells, their construction and operational mechanisms, efficiency, and overall stability. It explains the structure and functioning of PSCs, covering materials and components used for absorber layer, electron-transport layer, hole-transport layer, and electrodes. This review emphasized stability challenges associated with PSCs and discussed various factors and issues contributing to the degradation of these solar cells over time. It then provided a concise overview of different strategies and ongoing efforts taken to enhance the stability of PSCs. It also summarized various approaches used to improve their durability. In summary, this article offers a comprehensive exploration of PSCs, encompassing their construction, operation, improvement in efficiency, and obstacles related to their long-term stability. Furthermore, it addresses factors influencing PSC stability and outlines future challenges, focusing on prolonging their lifespan and enhancing stability for broader applications. Finally, this article has tackled various possible solutions to address the challenges encountered by the PSCs. [ABSTRACT FROM AUTHOR]