Electrode binders are conventionally regarded as inert structural components. Here, we show that in lead-free perovskite supercapacitors, the binder defines the optimal electrolyte composition. Across a factorial matrix of poly(vinylidene fluoride) (PVDF) loadings and LiTFSI concentrations in CsSnCl_3 electrodes, the capacitance optimum shifts systematically with binder content along a single linear relationship, described by the Interfacial Balance Rule (λ+θ=1), where λ and θ are the normalized lithium-supply and polymer contributions at the optimized interfacial state. The same relationship holds for hybrid MASnCl_3, showing that the optimum is governed by the polymer-electrolyte interface rather than the perovskite lattice chemistry. Simulations using a pre-trained MACE machine-learned interatomic potential show that PVDF adopts a planar configuration on CsSnCl_3 and simultaneously interacts with cationic and anionic sites. This configuration homogenizes lithium adsorption energetics, introduces fluorine-mediated coordination, and confines lithium to a two-dimensional interfacial region while preserving lateral mobility. Tuning polymer coverage through surface density and chain length reveals a finite interfacial lithium accommodation capacity that marks the onset of out-of-plane aggregation. The Interfacial Balance Rule provides a macroscopic descriptor of this finite interfacial resource, balancing polymer-mediated lithium stabilization against limited accommodation space. Binder loading is therefore an active design parameter for polymer-regulated energy-storage interfaces.

We present the design and fabrication of bifacial perovskite solar cells that possess remarkable transparency to infrared light. Our approach involves the incorporation of an oxide-metal-oxide structure-based hybrid top transparent electrode (TE) consisting of NiO/Ag/NiO (NAN). With feedback from optical modeling, NAN-TE was successfully fabricated with electrical sheet resistance as low as 5.04 Omega/sq, along with an average visible transmittance of similar to 80%, using a low-energy adatom-based physical vapor deposition technique. Incorporating the fabricated TE in the device configuration of ITO/SnO2/MAPbI(3)/Sprio-OMeTAD/NAN, a power conversion efficiency (PCE) of 9.05% and 6.54% was achieved when illuminated from the ITO and NAN side, respectively, demonstrating a high bifacility factor of 72%. In comparison, an opaque device showed a PCE of 13.61%. The devices also showed high durability, retaining 80% of their initial PCE for over 1000 h without any encapsulation in ambient environmental conditions. The device also exhibited significantly high light transmission (similar to 40%) in the 800- to 1200-nm near-infrared region. Furthermore, our NAN-TE has a total thickness of <40 nm, making it a potential TE for various optoelectronic applications due to its carefully engineered optical design. The demonstrated NAN-TE has immense potential to achieve outstanding performance in building integrated photovoltaics and tandem applications.

This study focuses on electrochemical energy that can be used as a catalyst to produce oxygen and hydrogen.

Iodine‐based hybrid planar perovskite solar cells’ (PSCs) overall performance is still very limited. In this work, a highly functionalized iodine‐based hybrid perovskite layer is fabricated by incorporating trimethylolpropane ethoxylated triacrylate (TET) within the perovskite precursor, which can crosslink with the grain boundaries to improve the crystallinity as well as the grain size and passivate the defect states of the perovskite material. The MAPbI 3 ‐based thin films with TET exhibited large grain sizes from 195.73 to 587.49 nm with 8 mg mL −1 of TET concentration. The X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X‐ray (EDX) elemental mapping, photoluminescence (PL), and time resolved photoluminescence (TRPL) characterization results suggest the strong crosslinking effect between TET and MAPbI 3 , which improves the crystallinity and reduces the charge trap density. Planar PSCs is fabricated with the device architecture fluorine‐doped tin oxide (FTO)/c‐TiO 2 /MAPbI 3 :TET/Spiro‐MeOTAD/Au and achieved a power conversion efficiency (PCE) of 14.75% under 1.5 AM light illumination. The fabricated PSCs shows excellent ambient stability which retains 80% of their PCE after being exposed to the ambient environment of relative humidity (RH) ≈60%, room temperature (RT) ≈27 °C without any encapsulation.

Semitransparent solar cells (ST-SCs) have emerged as a prominent energy harvesting technology that combines the benefits of transparency and light-to-electricity conversion. The biggest opportunities for ST-SCs lie in their integration as windows and skylights within energy-sustainable buildings or combining them with other solar cell technologies in tandem configuration. The performance of ST-SCs is mainly determined by the trade-off between the competing parameters of the capability to convert the light-to-electricity while allowing some part of it to pass through imparting transparency. Depending on the target application, the selection of ST-SCs is a tricky affair as some devices might offer high efficiency but compromise transparency and vice versa. In addition, this is again not helped by the fact that due to advancements in materials engineering, processing, and characterization, vastly different combinations of efficiency and transparency have been reported. So to quantify the performance of ST-SCs, we attempted and developed a figure-of-merit (FoM), which can be used as a tool that can help in analyzing and comparing the performance among various ST-SCs. The defined FoM focuses on the efficiency of the device, bifaciality factor, transmittance in the desired region, and that corresponding to 550 nm wavelength. Additionally, we have been shown how the proposed FoM can be correlated for tandem and building-integrated photovoltaics applications. Based on these resultant parameters, FoM is calculated and compared for different device architectures available in the literature. The proposed FoM shall serve as a meaningful guiding path to the researchers for the development of advanced ST-SCs. (c) 2023 Society of Photo-Optical Instrumentation Engineers (SPIE)

Flexible and lightweight photovoltaics have attracted great attention in recent years owing to their application in wearable and portable electronic devices. However, the use of polymer substrates obstructs the fabrication of highly efficient and stable devices due to their limitations like low transmittance, poor temperature tolerance, photodegradation, high material cost, etc. In addition, conventional flexible transparent electrodes (TEs) such as indium tin oxide (ITO) deposited on polymeric substrates have poor electro-optical properties compared to their glass counterpart and are still brittle, which not only negatively affect the performance but also the flexibility/ bendability. Here in this work, a kitchen-grade aluminium foil providing a lightweight, low-cost, mechanically flexible substrate-cum-electrode has been utilized for the very first time in the fabrication of perovskite solar cells. Also, an indium-free, oxide-metal-oxide (OMO) based TE exhibiting a sheet resistance below 6 omega/ and an average visible transmittance above 80% is used as a top TE. A power conversion efficiency (PCE) of over 10% is obtained with a high power per unit weight of over 3.5 W/g, which is much higher than conventional solar cells. The present work traces a way towards the fabrication of lightweight and flexible photovoltaic/optoelectronic devices by incorporation of metallic foil as substrate-cum-electrode.

Nitrogen-enriched nanoporous polytriazine (NENP) synthesized by conventional heating method possesses a high specific surface area (SA(BET)) of 966 m(2) g(-1), controlled pore size distribution (1.6, 5, and 8.3 nm) and total pore volume of 2.73 cm(3) g(-1). The synthesized specimen was utilized as an electrode material for supercapacitor (SC) application in non-aqueous media. The electrodes of NENP were fabricated by two approaches viz., conventional binder-based method and a binder-free electrophoretic deposition (EPD) approach. In case of electrode fabrication by controlled EPD process, the mass of 0.58 mg was obtained as the optimized mass achieved at pH = 2, deposition voltage = 20 V and deposition time = 6 min. The optimized electrodes and tetraethylammonium tetrafluoroborate in adiponitrile (TEA-BF4/ADP) non-aqueous electrolyte were used to fabricate symmetric supercapacitor devices (SC). The SC device, with EPD- based binder-free electrodes, exhibited higher specific capacitance (C-sp = 84 F g(-1)), energy density (E-sp = 118.8 Wh kg(-1)) and power density (P-sp = 17 kW kg(-1)) compared to SC device (49 F g(-1), 68.8 Wh kg(-1), and 11 kW kg(-1) at 0.8 A g(-1)) fabricated using electrode made from the binder based method. To enhance the SC performance, KI was added as a redox additive to the non-aqueous electrolyte (TEA-BF4/ADP). The SC device, with NENP binder-free electrodes and redox-active nonaqueous electrolyte (TEA-BF4/ADP/KI), achieved the highest C-sp, E-sp, and P-sp (112 F g(-1), 150.5 Wh kg(-1), and 27 kW kg(-1)) and demonstrated high cyclic stability (similar to 80.2 % initial capacitance retention after 30,000 cycles, at 5 A g(-1)).

Transition-metal-substituted manganese ferrites, Mn0.95M0.05Fe2O4 (M: Co, Cu, and Zn), synthesized by the combustion method exhibit a single-phase cubic spinel structure. A maximum specific surface area (SABET) of 125 m2 g-1 and a controlled pore size distribution (1.0 and 3.6 nm) and pore volume (0.17 cm3 g-1) were estimated for Mn0.95Zn0.05Fe2O4. All of these ferrites are used as active electrode materials for electrochemical supercapacitor applications. The best specific capacitance (Csp) and areal capacitance (Car) in nonaqueous electrolytes, i.e., 0.1 M lithium perchlorate/propylene carbonate (LiClO4/PC), were estimated for Mn0.95Zn0.05Fe2O4. Further, in order to understand the effect of redox additive electrolytes, the Csp and Car for Mn0.95Zn0.05Fe2O4 were measured in 0.1 M lithium perchlorate/propylene carbonate/tetraethylammonium tetrafluoroborate/ potassium iodide (LiClO4/PC/TEA-BF4/KI) along with non-redox-active electrolytes (LiClO4/PC). The electrodes were fabricated using Mn0.95Zn0.05Fe2O4 with optimized mass and exhibited high Csp and Car of 829 F g-1 and 1277 mF cm-2, respectively, in a redox-active electrolyte as compared to lower values of 452 F g-1 and 696 mF cm-2, respectively, at 1 mV s-1, in a non-redox-active electrolyte. A symmetric pouch cell supercapacitor device (SPCSDR) fabricated using Mn0.95Zn0.05Fe2O4 with a redox-active electrolyte (LiClO4/PC/TEA-BF4/KI) provides high energy (E) and power (P) densities of 77.5 W h kg-1 and 900 W kg-1, respectively, at 0.5 A g-1. The SPCSDR has demonstrated stability up to 8000 charge-discharge cycles with an initial Csp retention of -,80% and high Coulombic efficiencies of -,97-100%, at 2 A g-1.

Ultrathin metal films (UTMFs) have emerged as a potential contender as a transparent electrode (TE) in various optoelectronic applications. Oxide-metal-oxide (OMO) based TEs incorporating UTMFs are the new state-of-the-art approach towards fabricating high-performance indium-free TEs. Here, we have demonstrated an OMO-based indium-free TE utilizing nickel oxide (NiO) and silver (Ag) as oxide and metal films respectively. Optical constants of NiO and Ag obtained from spectroscopic ellipsometry have been utilized in determining the optimum thickness of alternate layers in the OMO stack using a MATLAB code based on the transfer matrix method. To minimize the reflection losses, 40 nm of NiO as films was deposited on either side of the Ag film. A highly transparent NiO/Ag/NiO (NAN) electrode has been obtained by the physical vapor deposition technique. The fabricated TE shows high transmittance >82% in the visible region along with a low sheet resistance below 6 Ω/□. To analyze the thermal stability of NAN-TE, it has been treated at different elevated temperatures. It was observed that NAN-TE shows better thermal stability in comparison to commercially available ITO-TE. The incorporation of NiO as an overcoat layer results in enhancing the work function to 5.35 eV as measured by Kelvin Probe Force Microscopy (KPFM). The high average visible transmittance, high work function, low sheet resistance, and high-temperature tolerance make the developed TE compatible with optoelectronic devices where high-temperature processing is necessary. To verify the same a bifacial perovskite solar cell is fabricated incorporating the NAN-TE as top TE and a power conversion efficiency (PCE) of 3.51% and 2.56% is obtained by illuminating the fabricated device from FTO and NAN side.

Measurement of optical constants of semiconducting thin films is an ongoing strive for optoelectronics and related applications. The optical constants (refractive index (n) and extinction coefficient (k)) plays a vital role in optimizing the thicknesses of different layers for improved performance in optoelectronic devices such as solar cells, photodetectors, light-emitting diodes, etc. In the present work, we measured the optical constants of methylammonium lead iodide (CH3NH3PbI3 or MAPbI3) deposited on five different underlying layers/substrates and estimated the error in simulated current density estimation for a device with the architecture of Glass/ITO/TiO2/CH3NH3PbI3/Spiro-OMeTAD/Au. The optical modeling and performance analysis of this device has been done using transfer matrix method while spectroscopic ellipsometry has been used to measure the optical constants of MAPbI3 film on five different types of underlayer stacks. A maximum error of around 10.6% has been observed when the optical constants are taken from MAPbI3 films deposited on the different underlying stacks. Additionally, experimental aspects of these films such as surface morphology, structural, and optical properties have also been studied to better understand and correlate the observed differences.

Oxide–metal–oxide (OMO)‐based stacks are highly attractive by virtue of their favorable properties for being used as a top transparent electrode (TE) in semitransparent solar cells. Herein, getting the best trade‐off between performance and transparency is focused on by optimizing the OMO electrode and the device layers with the help of optical simulation. NiO/Ag/SnO 2 as the OMO electrode integrated into a device having SnO 2 , Spiro‐OMeTAD, and MAPbI 3 as the electron transport layer, hole transport layer, and photoactive layer, respectively, in n–i–p geometry is investigated. It is shown that an optimized OMO electrode in terms of average visible transparency (AVT) does not translate to the best device performance. It is found that for the overcoat to undercoat oxide layer ratio of 1.17, a maximum short‐circuit current density ( J SC ) of 4.34 mA cm −2 is achieved while a maximum AVT of 21.55% is obtained for a ratio of 0.78. On further optimization of the MAPbI 3 thickness, for an oxide ratio of 1, a modeled device with 4.58 mA cm −2 with AVT of 31.55% is demonstrated. In addition, it is also found that by integrating an optical spacer layer after the OMO electrode, the J SC of the device shows a jump of >115% to 9.86 mA cm −2 .

Following an approach combining optical modeling and experimental study in this proposed work, we report designing and fabrication of MoO3/Ag/MoO3 transparent electrode (MAM-TE) for perovskite solar cell (PvSC) applications. We started with the optical design of the TE to determine the optimized thickness of the alternating layers. Variable angle spectroscopic ellipsometry was employed to find the accurate optical constants of each layer which works as the input parameter for the Transfer Matrix Method (TMM) based Matlab code. With the help of optical modeling, the optimum thickness of the undercoat and overcoat oxide layer is calculated. The thickness of the metal layer (Ag) is kept fixed at 9 nm as it is found to be thick enough to provide good electrical conductivity. In this work, we investigated the effect of the rate of deposition (RoD) of sandwiched Ag layer on the optical and electrical behavior of MAM-TE. For a better understanding of the effect of RoD on Ag, characteristics of Ag films are performed via scanning electron microscopy (SEM) and optical absorption spectroscopy (UV–Visible). Transmittance spectra revealed that as the RoD of the Ag layer is increased from 0.5 Å/s to 5 Å/s, the films become more transparent, which is in good agreement with SEM images of the deposited Ag films. In this way, keeping the RoD of the Ag layer fixed at 5 Å/s, we successfully fabricate a highly transparent MAM-TE with an average visible transmittance > 77 %, along with a sheet resistance < 5 Ω/□. After the complete optimization of fabricated TE, it is finally incorporated into a perovskite solar cell device architecture consisting of FTO/TiO2/MAPI/Spiro/MAM. The preliminary results of the fabricated PvSC give a power conversion efficiency (PCE) of 4.79 %. Hence, the fabricated TE can integrate routes for its revolutionizing applications in diverse fields, including optoelectronic industries and bifacial photovoltaics applications.

Here we have demonstrated an indium-free transparent electrode (TE) consisting of an ultrathin silver film in combination with zinc oxide as undercoat and overcoat layer. The oxide layers help to minimize the inherent reflection of the metal film while the silver layer provides the conductivity. Electrical and optical properties of this TE have been investigated using four probe and UV-Vis spectrophotometer. Before the experimental realization of the TE, an optical simulation based on transfer matrix method has been performed to calculate the optimum thickness of the undercoat and the overcoat oxide layer to minimize the reflection loss and to get the highest transmittance. The simulation results show that thickness equal to 40 nm for both undercoat and overcoat ZnO layer gives the highest transmittance. A transmittance value above 90% (at 550 nm) with average transmittance above 85% in the visible region has been obtained theoretically and realized experimentally along with the sheet resistance below 6 omega/?. Hackke's figure of merit and sigma(DC)/sigma(OP) values for this ZnO/Ag/ZnO (ZAZ)-TE comes out to be better than commercially available ITO. The deposited TE and commercially available ITO were treated under different temperatures (200, 350, and 500 degrees C) to analyse their stability towards elevated temperature and it has been observed that ZAZ shows better stability towards temperature when compared to ITO. The high-temperature stability of this TE shows its potential for various optoelectronic applications including solar cells. Such TEs can be used in device fabrication at a higher temperature without compromising performance. Copyright (C) 2022 Elsevier Ltd. All rights reserved.

Semi-transparent Solar Cells (ST-SCs) has emerged as one of the most prominent energy harvesting technology that combines the benefits of light transparency and light-to-electricity conversion. The biggest opportunities for such technologies lie in their integration as windows and skylights within energy-sustainable buildings or combining them with other solar cell technologies in tandem configuration. The performance of ST-SCs is mainly determined by the trade-off between the competing parameters of the capability to convert the incident light into electricity while allowing some parts to transmit providing transparency through the device. Depending on the target application, the selection of ST-SCs is a tricky affair as some devices might offer high efficiency but compromises transparency and vice-versa. On the other way around, this is again not helped by the fact that due to advancements in materials engineering, processing, and characterization, a vastly different combination of efficiency and transparency has been reported by research groups. So, in order to quantify the performance of ST-SCs, we proposed, a figure-of-merit (FoM) which can be used as a tool that can help in analysing and comparing the performance among various ST-SCs. The defined FoM focuses on the power conversion efficiency of the device, bifaciality factor, transmittance in the desired region, and that corresponding to 550 nm wavelength. Additionally, in this work, we have been shown how the proposed FoM can be correlated for tandem and building-integrated photovoltaics applications. Based on these resultant parameters, FoM is calculated and compared for different device architectures available in the literature. The proposed FoM shall serve as a meaningful guiding path to the researchers for the development of advanced ST-SCs.

Organic–inorganic lead halide perovskite is promising photovoltaic energy harvesting material to fabricate high-efficiency solar cells. To enhance the power conversion efficiency (PCE) and stability of the fabricated device, a high-quality, pinhole-free, and larger grain size perovskite film is essential. Anti-solvent-assisted crystallization is a popular technique to deposit perovskite thin film. With the help of this technique, perovskite layer can be deposited with smooth surface morphology, low surface defect density, and excellent carrier transport. However, choosing a proper anti-solvent is essential for highly efficient perovskite solar cells (PvSCs). Here, we qualitatively evaluate the impacts of different anti-solvent on methylammonium lead iodide (MAPbI 3 ) perovskite film. We used chlorobenzene (CB), diethyl ether (Eth), toluene (TL), and isopropyl alcohol (IPA) as an anti-solvent. Our result demonstrates that the anti-solvent with a relatively higher boiling point and lower polarity contributes to superior efficiency, low hysteresis, and better reproducibility of MAPbI 3 active layer-based PvSCs. The device fabricated with CB anti-solvent exhibits the best PCE of 8.16% with a Cu-based electrode. This work provides a promising approach to controlling the growth and morphology of perovskite films and paves the way for further optimizing the fabrication process of large-area low-cost electrode-based high-efficiency devices.

The use of inorganic materials is generally considered a prerequisite for the realization of inexpensive and long-lasting perovskite solar cells (PvSCs). Herein, we have demonstrated a low-cost, inorganic, ultrathin thermally oxidized copper film (Cu_Oxd) as a hole transport layer (HTL) in PvSC in p-i-n geometry with MAPbI3 as the photoactive layer. A highly reproducible technique of vapor deposition (magnetron sputtering) followed by thermal annealing has been used to deposit the Cu_Oxd layer over an ITO-coated glass substrate. The material properties of the Cu_Oxd film have been thoroughly investigated and their effect on photovoltaic properties and the photoactive absorbing layer has been studied in detail and correlated. Photovoltaic performance of the devices fabricated with different Cu_Oxd thicknesses has been measured and a maximum PCE of 11.44% has been obtained with a 5 nm thickness of Cu_Oxd layer as HTL with a pixel area of 0.25 cm2. The devices showed higher stability with T80 lifetime >1000 h without any encapsulation. With the ease of fabrication and compatibility with large-area devices, Cu_Oxd as HTL can be scaled up and also, help in the progress towards large-scale fabrication and commercialization.

Perovskite solar cells (PSCs) have emerged as a promising technology for next-generation photovoltaic devices because of their ease of fabrication and high power conversion efficiency (PCE). The main obstacle that limits the commercialization of large-area PSCs is the lack of suitable solution-processable low-temperature fabrication methods and the perovskite material's chemical stability. With an increase in the active area of the cell, the defect states and the series resistance of the device increase, which is undesirable. We have demonstrated a repeatable fabrication method of small (0.25 cm2) and large (2.0 cm2) active area devices with Au and Cu as back contact electrodes. Small area perovskite devices with Cu and Au contact electrodes showed a PCE of 9.87% and 10.42%, respectively. When scaled up to 2.0 cm2, the devices showed a minor drop in the open-circuit voltage, but a significant decrease in photocurrent was observed. Large-area PSCs with Cu and Au contacts displayed a PCE of 5.61% and 5.92%, respectively. External quantum efficiency measurements at four different points provided similar results, thus confirming the uniformity of large-area devices. The stability of large-area devices under ambient environment conditions was tested for more than 7 weeks. Gold-based PSC retained almost 75% of its initial PCE when stored in ambient conditions for 50 days, whereas Cu-based devices showed a significant decrease in efficiency in the same period. Degradation in efficiency of PSCs occurred primarily due to the loss in photocurrent arising from active layer degradation. Simulations of perovskite devices carried out using Solar Cell Capacitance Simulator (SCAPS)-1D software also showed that similar efficiencies of PSCs may be obtained using Cu, instead of Au, as the low-cost metal contact. Novelty Statement Large-area perovskite solar cells (PSCs) based on gold and copper metal contacts have been fabricated, and copper contacts provide efficiencies comparable with the values obtained with gold contacts. The study shows that copper can be used as a low-cost alternative to gold to fabricate large-area, high-efficiency PSCs. Stability testing under ambient conditions has been carried out for 50 days to compare the performance of gold- and copper-based large-area PSCs.

In semi-transparent perovskite solar cells (ST-PvSC), the thicknesses and choice of charge transport layers and transparent electrode (TE) becomes more prominent in determining the performance and transparency of the device. In this work, we report the potential of NiO/Ag/NiO (NAN) as a top TE for ST-PvSC with methylammonium lead iodide (MAPI) as an absorbing material. Optical simulation based on the transfer matrix method (TMM) is used to optimize the NAN electrode and the whole device. NAN-TE with optimized NiO (37 nm)/Ag(9 nm)/NiO(34 nm) structure gives an average visible transmittance (AVT) of 86.60%. In addition, most of the prior works focus on using spiro-OMeTAD as hole transporting material (HTM), which has poor stability and is expensive. In our device architecture, NiO satisfying the energy level requirement is explored as an alternative to spiro-OMeTAD. Here in NAN-TE, the bottom NiO in contact with the perovskite layer not only works as a layer that helps to reduce the reflection loss due to the Ag layer but also as an HTM. In this work, we also studied the performance of different electron transporting materials (ETM) like TiO2, AZO, and ZnO in combination with the NAN-TE. When simulated with different ETM layers, TiO2 is found to be the best performing. The reported work enlightens the capability of NAN-TE for making devices not only semi-transparent but also in making a good interface with the active layer from the electrical point of view. Taking the optimized values of all layers in the device structure-Glass/ITO (100 nm)/TiO2 (40 nm)/MAPI (100 nm)/NiO (37 nm)/Ag (9 nm)/NiO (34 nm) a J(SC) value of 16.66 mA/cm(2) and AVT of 31.49% for the device has been reported. Further, the use of NiO as HTM in place of spiro-OMeTAD has a greater impact on the stability and cost of the device. Copyright (c) 2022 Elsevier Ltd. All rights reserved.