Increase In Power Conversion Efficiency Research Articles

Post‐Treatment of Metal Halide Perovskites: From Morphology Control, Defect Passivation to Band Alignment and Construction of Heterostructures

AbstractMetal halide perovskite solar cells (PSCs) have witnessed a swift increase in power conversion efficiency in the past decade, emerging as one of the most promising next‐generation photovoltaic technologies for commercialization and low‐carbon energy generation. Through significant efforts in optimizing the processing techniques, high‐quality perovskite thin films can now be prepared with polycrystalline morphologies consisting of monolayer grains. Nevertheless, defects and microstructural disorders still form at the surface/heterointerface and in the bulk of the films. Post‐treatment of the as‐crystallized films has been intensively investigated for passivating these defects, being proved effective for improving the device performance. In this review, the versatile strategies for post‐treating the surface of perovskite thin films toward morphology control, defect passivation, and band alignment are discussed. The tailored surface properties are correlated to charge dynamics at interfaces and photovoltaic performance of PSCs. Since the perovskite heterostructures prepared by simple post‐treatments may suffer from degradation at high temperatures, the recent advances in preparing phase‐pure and stable perovskite heterostructures are also discussed. Finally, a perspective elaborating future opportunities for further enhancing the efficiency and stability of PSCs is provided.

Interfacial defect passivation by multiple-effect molecule for efficient and stable perovskite solar cells

Perovskite solar cells (PSCs) have attracted a lot of attention from researchers as the most promising photovoltaic devices due to their outstanding power conversion efficiency (PCE) and low-cost. Although the PSC have reached a PCE over 25%, the interface between the perovskite and hole transport layer (HTL) still is a crucial factor limiting higher PCE and long-term stability. In this work, we choose an organic molecule Bis(trifluoromethyl)benzo amide (BTFZA) to passivate defects at the perovskite/HTL interface. Owing to a strong interaction with uncoordinated Pb2+, the BTFZA effectively passivated the surface defects, remarkably promoted carrier transportation. As a result, the perovskite device based on BTFZA surface modification showed a PCE increase of 16.4% over the control device. Especially, the fill factor (FF) and the open-circuit voltage (VOC) of the modified device increased significantly. In addition, the unencapsulated BTFZA-modified device maintains better PCE compared to the control device after aging for over 600 h in ambient air with extreme humidity and temperature conditions. Results suggested that the introduction of BTFZA is an effective way to regulate the surface of perovskite film aiming at highly efficient and stable perovskite solar cells.

P-Type Functionalized Carbon Nanohorns and Nanotubes in Perovskite Solar Cells.

The incorporation of p-type functionalized carbon nanohorns (CNHs) in perovskite solar cells (PSCs) and their comparison with p-type functionalized single- and double-walled carbon nanotubes (SWCNTs and DWCNTs) are reported in this study for the first time. These p-type functionalized carbon nanomaterial (CNM) derivatives were successfully synthesized by [2 + 1] cycloaddition reaction with nitrenes formed from triphenylamine (TPA) and 9-phenyl carbazole (Cz)-based azides, yielding CNHs-TPA, CNHs-Cz, SWCNTs-Cz, SWCNTs-TPA, DWCNTs-TPA, and DWCNTs-Cz. These six novel CNMs were incorporated into the spiro-OMeTAD-based hole transport layer (HTL) to evaluate their impact on regular mesoporous PSCs. The photovoltaic results indicate that all p-type functionalized CNMs significantly improve the power conversion efficiency (PCE), mainly by enhancing the short-circuit current density (Jsc) and fill factor (FF). TPA-functionalized derivatives increased the PCE by 12-17% compared to the control device without CNMs, while Cz-functionalized derivatives resulted in a PCE increase of 4-8%. Devices prepared with p-type functionalized CNHs exhibited a slightly better PCE compared with those based on SWCNTs and DWCNTs derivatives. The increase in hole mobility of spiro-OMeTAD, additional p-type doping, better energy alignment with the perovskite layer, and enhanced morphology and contact interface play important roles in enhancing the performance of the device. Furthermore, the incorporation of p-type functionalized CNMs into the spiro-OMeTAD layer increased device stability by improving the hydrophobicity of the layer and enhancing the hole transport across the MAPI/spiro-OMeTAD interface. After 28 days under ambient conditions and darkness, TPA-functionalized CNMs maintained the performance of the device by over 90%, while Cz-functionalized CNMs preserved it between 75 and 85%.

Enhancing Light Harvesting in Dye-Sensitized Solar Cells through Mesoporous Silica Nanoparticle-Mediated Diffuse Scattering Back Reflectors

Dye-sensitized solar cells (DSSCs) hold unique promise in solar photovoltaics owing to their low-cost fabrication and high efficiency in ambient conditions. However, to improve their commercial viability, effective, and low-cost methods must be employed to enhance their light harvesting capabilities, and hence photovoltaic (PV) performance. Improving the absorption of incoming light is a critical strategy for maximizing solar cell efficiency while overcoming material limitations. Mesoporous silica nanoparticles (MSNs) were employed herein as a reflective layer on the back of transparent counter electrodes. Chemically synthesized MSNs were applied to DSSCs via bar coating as a facile fabrication step compatible with roll-to-roll manufacturing. The MSNs diffusely scatter the unused incident light transmitted through the DSSCs back into the photoactive layers, increasing the absorption of light by N719 dye molecules. This resulted in a 20% increase in power conversion efficiency (PCE), from 5.57% in a standard cell to 6.68% with the addition of MSNs. The improved performance is attributed to an increase in photon absorption which led to the generation of a higher number of charge carriers, thus increasing the current density in DSSCs. These results were corroborated with electrochemical impedance spectroscopy (EIS), which showed improved charge transport kinetics. The use of MSNs as reflectors proved to be an effective practical method for enhancing the performance of thin film solar cells. Due to silica’s abundance and biocompatibility, MSNs are an attractive material for meeting the low-cost and non-toxic requirements for commercially viable integrated PVs.

Efficiency enhancement of GaAs nanowire array-based solar cell by plasmonic Al nanoparticles

Gallium arsenide (GaAs) nanowire (NW) solar cells (SCs) have piqued the interest of researchers because they exhibit superior light-harvesting and anti-reflection properties along with reduced material consumption compared to their planar counterparts. However, the high surface-to-volume ratio associated with these NWs degrades their performance in practical applications. Light trapping is considered one of the most crucial parameters for producing low-cost high-efficiency NW-SCs. Thus, numerous light-trapping strategies have been explored, among which surface plasmon resonance (SPR) based optical absorption enhancement using metal nanoparticles (NPs) has emerged as a potential method. The role of plasmonic aluminum (Al) NPs in the efficiency enhancement of GaAs NW SC has not yet been explored. Therefore, in this study, a vertically aligned GaAs NW SC structure incorporated with Al NPs has been investigated using the finite-difference time-domain (FDTD) method. The sidewalls of GaAs NWs are embellished with uniformly arranged Al NPs with diameters ranging from 30 to 60 nm. The excitation of localized surface plasmon resonance in metal NPs results in significant light absorption enhancement at the GaAs near-band of the proposed structure. The results demonstrate that even with a low aspect ratio (D/P) of 0.3, optimizing the geometrical parameters of the NPs results in a 41.96 % increase in power conversion efficiency (PCE) and a 45 % increase in absorption efficiency at 800 nm for the proposed structure when compared to the bare structure. Hence, our suggested structure which utilizes the light-trapping mechanism of Al NPs proves to be a cost-effective and promising material combination for high-efficiency nanoscale SCs.

Synergistic Effects of Localized Surface Plasmon Resonance, Surface Plasmon Polariton, and Waveguide Plasmonic Resonance on the Same Material: A Promising Hypothesis to Enhance Organic Solar Cell Efficiency.

This work explores the utilization of plasmonic resonance (PR) in silver nanowires to enhance the performance of organic solar cells. We investigate the simultaneous effect of localized surface plasmon resonance (LSPR), surface plasmon polariton (SPP), and waveguide plasmonic mode on silver nanowires, which have not been thoroughly explored before. By employing finite-difference time-domain (FDTD) simulations, we analyze the plasmonic resonance behavior of a ZnO/Silver nanowires/ZnO (ZAZ) electrode structure. Our investigations demonstrate the dominance of LSPR, leading to intense electric fields inside the nanowire and their propagation into the surrounding medium. Additionally, we observe the synergistic effects of SPP and waveguide plasmonic mode, contributing to enhanced light absorption within the active layer of the organic solar cell. This leads to an improvement in photovoltaic performance, as demonstrated by our previous work, showing an approximate 20% increase in photocurrent and overall power conversion efficiency of the organic solar cell. The incorporation of metallic nanostructures exhibiting these multiple plasmonic modes opens up new opportunities for improving light absorption and overall device efficiency. Our study highlights the potential of these combined plasmonic effects for the design and optimization of organic solar cells.

Enhancing perovskite solar cells performance via sewing up the grain boundary

Grain boundaries (GBs) are inevitable for the solution-processed perovskite polycrystalline films, but they become the weakest regions when the film undergoes degradation, especially unreacted PbI2 prefers to locate at GBs. Herein, this issue is solved by applying hydroxyl functionalized ionic liquids (ILs) on perovskite solar cells (PSCs). The ILs sew up the GBs continuously through in situ formation of a plumbite complex with residual PbI2. By sewing-up the GBs, the PSCs afford a notable increase in both power conversion efficiency (PCE, from 21.49% to ∼24.00%) and device stability (remaining over 80% of the initial PCE after 600 h at 60 ℃, 90% of the initial PCE after 2000 h in a constant humidity environment of 40% RH, and 85% of its PCE under continuously light illumination for 700 h). These improvements are ascribed to the precise passivation of related defects, optimization of interfacial energy level, suppression of the charge recombination, and enhancement of charge collection through sewing-up the GBs. This “sewing-up grain boundaries” method is highly promising toward construction of robust films for solution-process PSCs.

Zinc-bis-8-hydroxyquinoline doped by biochar extracted from red sea algae Chlorophyta as a novel photoactive layer in heterojunction solar cells

Recently, scientists have shown interest in utilizing biochar made from natural sources to enhance various photovoltaic technologies. In this study, Zinc-Bis-8-hydroxyquinoline (Zn-Hq2) was mixed with 10 % biochar obtained from red sea microalgae (Chlorophyta) using a microwave combustion process. This mixture was then used as a novel photoactive layer in a solar cell. The structural properties of Zn-Hq2@BC were analyzed by XRD, FTIR, HRTEM, and SEM. The analysis showed that Zn-Hq2@BC had evenly distributed nano-rods within the BC nanopores network, with widths ranging from 26.94 to 30.90 nm and lengths ranging from 136.43 to 192.38 nm. When measuring dark current density-voltage, it was found that Zn-Hq2@BC/n-Si showed better-rectifying characteristics compared to pristine Zn-Hq2/n-Si, with a higher rectification ratio. The results also showed that the current density and voltage at the maximum power point increased to 5.63 mA/cm2 and 0.45 V, respectively, due to the activation of the biochar. When exposed to light, the addition of approximately 10 % biochar resulted in a 15 % increase in fill factor and a 92 % increase in power conversion efficiency. This is because biochar helps introduce extra charge carriers into the material, thus improving charge transport and reducing recombination losses. These findings reveal the positive effects of microalgae-derived biochar and indicate potential applications of Zn-Hq2 in solar cells.

Tailoring the electronic properties of the SnO2 nanoparticle layer for n-i-p perovskite solar cells by Ti3C2TX MXene

The effect of the Ti3C2Tx MXene modification of the SnO2 electron transport layer (ETL) was studied for the concentration range 0–7.4 wt% MXene. The electronic properties of the MXene-modified ETL were studied by the electrical conductivity measurements, density of states mapping by the energy-resolved electrochemical impedance spectroscopy, ultraviolet photoelectron spectroscopy, and photoluminescence. The structure and morphology of the MXene-modified ETL and the top perovskite layer were analyzed by the scanning electron microscopy (SEM), scanning transmission electron microscopy, grazing-incidence X-ray diffraction and in situ grazing-incidence wide-angle X-ray scattering (GIWAXS). The increased electrical conductivity and electron selectivity for the MXene-modified SnO2 ETL was confirmed up to 1 wt% MXene. For 7.4 wt% MXene, significant suppression of the hole blocking property of the ETL was found. The in situ GIWAXS was performed during the post-deposition annealing of the perovskite layer. The increased perovskite grain size on the SnO2 ETL modified by MXene compared to the pure SnO2 ETL visible by SEM was confirmed. The uniaxial texture of the perovskite crystals was revealed in both cases with an increased misorientation angle for the MXene-modified ETL. The grain size and misorientation angle do not exhibit any systematic temporal changes during the post-deposition annealing. The increasing number of the grains during the annealing was observed. These results are explained using the nucleation and growth model. The increased power conversion efficiency from 17.4% to 18.3% of the archetypal methylammonium-lead-iodide perovskite solar cell after the modification of the SnO2 ETL with 0.1 wt% MXene is the effect of two contributions - increased electrical conductivity of the ETL and improved crystallinity and larger grain size compared to the pure SnO2 ETL, which lowers the total boundary area and charge recombination at trap states typically formed at grain boundaries.

Mechanism of improvement of efficiency of Cu2ZnSn(S,Se)4 solar cells by optimization of deposition temperature of CdS buffer layer

The physical properties of CdS buffer layers and the interface quality between CdS layer and Cu2ZnSn(S,Se)4 (CZTSSe) absorber have a significant impact on the performance of CZTSSe solar cells. In the present work, five types of CZTSSe solar cells with conventional structure (denoted as CdS-x-cells, x = 55, 60, 65, 70 and 75) were fabricated by using CdS prepared at deposition temperatures of 55, 60, 65, 70 and 75 ℃, respectively, as buffer layer, and influence mechanism of the deposition temperature of CdS layers on power conversion efficiency (PCE) of the CdS-x-cells was investigated. It is found that the PCE of the CdS-x-cells increases from 8.52% to 10.36% as the deposition temperature rises from 55 to 60 ℃ but falls from 10.36% to 7.14% from 60 to 75 ℃. The analysis on the photovoltaic and electrical parameters indicates that the increase in PCE is predominantly derived from the decreased reverse saturated current density (J0), followed by the decreased series resistance (RS) and increased shunt resistance (RSh). The decreased PCE with the further increasing deposition temperature is mainly contributed from the increased J0, followed by the decreased RSh and photogenerated current density (JL). The influence mechanism of deposition temperature of the CdS layer on PCE is suggested via quantitatively analysis of influence of electrical, optical properties and crystal quality of CdS prepared at various deposition temperatures on JL and electrical parameters of CdS-x-cells. This work is helpful for improvement of PCE of CZTSSe solar cells by modification of properties of buffer layer.

Surface engineering of mesoporous-TiO2 electron transport layer for improved performance of organic-inorganic perovskite solar cells via suppressing interface defects, enhancing charge extraction and boosting carrier transport

Organic-inorganic perovskite solar cells (PrSCs) have emerged as a promising solar photovoltaic technology in terms of realizing high power conversion efficiency (PCE). However, their limited lifetime and poor device stability limit their commercialization in future. In this regard, interface engineering of the electron transport layer (ETL) using 2D materials have been currently used owing to their high carrier mobility, high thermal stability and tunable work function which in turn enormously impact the charge carrier dynamics. In this work, we report an easy and effective way of simultaneously enhancing the efficiency and air-stability of PrSCs via interface engineering by incorporating 2D-MoS2 (bi/tri-layered) in mesoporous-titanium dioxide (mp-TiO2) scaffold electron transport buffer layer, and using CVD grown perovskite layers. The PrSCs were fabricated in ambient air conditions in device configuration, FTO/c-TiO2/mp-TiO2:2D-MoS2/CH3NH3PbI3/P3HT/Au, with an active area of 0.16 cm2. The best device using c-TiO2/mp-TiO2:2D-MoS2 (0.5 wt%) ETL exhibited a substantial increase in PCE ∼13.04% as compared to PCE ∼8.75% realized in reference device fabricated without incorporating MoS2 in mp-TiO2 buffer layer. The incorporation of MoS2 nanoflakes in mp-TiO2 ETL not only enhances the PCE to ∼49%, but also improve the lifetime (retaining PCE ∼86% of its initial value up to 500 hrs, without encapsulation). The enhancement in performance of c-TiO2/mp-TiO2:2D-MoS2 ETL based devices as compared with reference c-TiO2/mp-TiO2 ETL based devices is attributed to, (i) reduction in the work function of mp-TiO2 ETL buffer on dispersion of 2D-MoS2 nanoflakes forming of a perfect interface at ETL/perovskite offering extremely less interfacial energy barrier to promote the charge extraction process at the interface, and suppress the surface recombination losses, (ii) fast charge collection as 2D-MoS2 in TiO2 strongly support the electron transport due to their highly crystalline nature, and (iii) lifetime improvement due to better moisture stability of 2D-MoS2 and high quality of chemical vapor grown perovskite thin films. This work presents an efficient mp-TiO2:2D-MoS2 scaffold ETL for realizing high performance, low cost, air-processed PrSCs for their future development.

Two-Dimensional Graphitic Carbon Nitride for Improving the Performance of Organic Solar Cells.

Organic solar cells (OSCs) have attracted lots of attention owing to their low cost, lightweight, and flexibility properties. Nowadays, the performance of OSCs is continuously improving with the development of active layer materials. However, the traditional hole transport layer (HTL) material Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) presents insufficient conductivity and rapid degradation, which decreases the efficiency and stability of OSCs. To conquer the challenge, the two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanomaterials incorporated into the PEDOT:PSS as hybrid HTL are reported. The addition of g-C3N4 into PEDOT:PSS enables the thickness of the HTL to decrease for enhancing the transmittance of the film and increase the conductivity of PEDOT:PSS. Thus, the device exhibts improved charge transport and suppressed carrier recombination, leading to the increase in short-circuit current density and power conversion efficiency of the devices. This work demonstrates that the incorporation of 2D g-C3N4 into PEDOT:PSS for D18:Y6 and PM6:L8-BO-based OSCs can significantly improve the device efficiency to 17.48% and 18.47% with the enhancement of 7.04% and 8.46%, respectively.

Atomic-layer-deposited H:MoOx function layer as efficient hole selective passivating contact in silicon solar cells

Transition metal oxides deposited by Atomic Layer Deposition (ALD) exhibit the potential to allow for doping modification by different reaction precursors and annealing during the deposition process. In this work, we demonstrate ALD-deposited hydrogenated molybdenum oxide (H:MoOx) as an efficient hole selective passivating contact for p-type crystalline silicon solar cell. The precursor and deposition temperature has a significant impact on the H:MoOx thin films, leading to the variation in degree of hydrogenation and work function. Employing H:MoOx thin films as hole selective passivating contacts for c-Si(p), a low contact resistivity of 72.6 mΩ cm2 and a high iVoc of 624 mV can be realized. Finally, c-Si(p) solar cell with H:MoOx thin film as hole selective passivating contact showed an increased power conversion efficiency from 15.48% (without H:MoOx) to 17.23% (with H:MoOx). The results show an effective stage to employ ALD-deposited high work function hydrogenated transition metal oxide as hole selective passivating contact.

Perovskite Solar Module: Promise and Challenges in Efficiency, Meta‐Stability, and Operational Lifetime

AbstractPerovskite photovoltaics (PVs) are an emerging solar energy generation technology that is nearing commercialization. Despite the unprecedented progress in increasing power conversion efficiency (PCE) for perovskite solar cells (PSCs), up‐scaling lab‐made cells to solar modules remains a challenge. In this work, the recent progress of making perovskite mini‐modules is reviewed. In particular, a database summarizing the module size, performance, hysteresis, and operational lifetimes reported in the literature is built. After analyzing the performance losses from scaling PSCs to mini‐modules based on the data collected from the literature, the current key to high‐performance perovskite mini‐modules is found to be the coating method optimization. If the perovskite layer quality is well reserved, a >24% mini‐module efficiency is projected by only considering the losses from lateral resistivity and laser scribing area. Next, performance characteristics are explored including hysteresis and meta‐stable power outputs that must be overcome to correctly characterize perovskite modules. Finally, current challenges associated with the long‐term stability of perovskite modules are examined and the importance of such durability for commercialization is discussed. It is hoped that the findings in this review provide a bridge for the development of perovskite modules that will lead to commercialization in the near future.

BaSnO3-SnO2 heterojunction mesoporous photoanode for quantum dot-sensitized solar cells

Mesoporous photoanodes, as quantum dot adsorption framework and electron transfer paths, are the key components in efficient quantum dot-sensitized solar cells (QDSSCs). Binary heterojunction mesoporous photoanodes hold promise for facilitating electron transport due to the heterojunction potential, when compared to conventional mono-component mesoporous photoanodes. In this work, we construct a binary mesoporous photoanode with enhanced mesoporous and electron transport using a BaSnO3-SnO2 heterojunction, and then fabricated CdSe/CdS co-sensitized QDSSCs. The charge extraction, open-circuit voltage decay, electrochemical impedance spectroscopy, and intensity-modulated voltage/photocurrent spectroscopy measurements demonstrated that, in contrast to the BaSnO3 mesoporous photoanode, the BaSnO3-SnO2 mesoporous photoanode could effectively reduce charge recombination and extend the electron lifetime, thus promoting charge collection in the QDSSCs. Based on these merits, the BaSnO3-SnO2 mesoporous photoanode-based solar cells yielded a power conversion efficiency of 3.14%, resulting in a ca. 11% increase in power conversion efficiency, compared to the reference BaSnO3 solar cells.

Improving photovoltaic performance of light-responsive double-heterojunction nanorod light-emitting diodes.

Double heterojunction nanorods enable both electroluminescence and light harvesting capabilities within the same device structure, providing a promising platform for energy-scavenging displays and related applications. However, the efficiency of the photovoltaic mode remains modest for useful power conversion and may be challenging to improve without sacrificing performance in electroluminescence. Through a facile on-film partial ligand exchange with benzenethiol integrated into the device fabrication step, we achieve an average of more than threefold increase in power conversion efficiency while maintaining the maximum external quantum efficiency and the maximum luminance in the LED mode. The improved photovoltaic performance is mainly due to the increase in the short circuit current, which we attribute to the enhanced charge separation afforded by the partial ligand exchange. The recovery of the photoluminescence lifetime under the forward bias suggests that the hole traps introduced by benzenethiols are filled prior to reaching the voltage at which light emission begins, allowing LED performance to be maintained and possibly improved.

Facile and versatile fabrication process for AgNW/GZO transparent composite electrodes for photovoltaic applications by atmospheric pressure plasma jet

Transparent conductive oxide (TCO) must have high electrical conductivity and optical transmittance. Using higher doping concentrations improves the conductivity but often at the expense of transmittance in the near-infrared regime. Using thicker film to improve the conductivity is not preferable as it significantly reduces the transmittance. Silver nanowire (AgNW)/ TCO composite film has been proposed as a viable method to address this dilemma. However, AgNWs often require additional thermal treatment to weld the nanowires to reduce the contact resistance. Also, thermal treatment apparatus, such as lasers, cannot be easily integrated into the TCO deposition setup, adding extra cost for handling samples. Here we use an atmospheric pressure plasma jet (APPJ) to fabricate AgNW/ TCO composite films—APPJ successfully welds the AgNWs and covers them with a thin gallium-doped ZnO or GZO protective layer simultaneously. The AgNW weight significantly affects the optoelectronic and morphological properties and can be tailored to fit the requirements of particular photovoltaic applications. Our perovskite solar cells with the AgNW/GZO front electrodes exhibit a ∼21% increase in power conversion efficiency. Furthermore, unlike conventional methods, our approach is vacuum-free and does not require additional processes, such as lasers, to treat the AgNW network, which may greatly reduce operational complexity.

Tris-homoleptic cyclometalated Ir(III) complexes based on oligothiophene-derived ligands as electron donors for organic solar cells

Herein, two octahedral homoleptic tris-Ir(III) complexes namely Py3T3Ir and Py5T3Ir are designed from pyridine/oligothiophene hybridized cyclometalated ligands with different conjugation lengths. Py5T3Ir with enlarged conjugation shows bathochromic absorption, strengthened absorptivity in longer-wavelength region and lower-lying energy levels compared to Py3T3Ir. Moreover, Py3T3Ir bearing small-sized backbones presents stronger triplet characteristic with boosted phosphorescence and prolonged exciton lifetimes. Blending ZY-4Cl acceptor to construct all-small-molecule organic solar cells, Py5T3Ir performs evidently increased power conversion efficiency of 8.62% than 3.04% of Py3T3Ir. The pronounced improvement in photovoltaic performance is originated from the advantageous carrier dynamics and superior blend morphology. Our results indicate coordinated Ir complexes are expected as potential photovoltaic materials by judicious molecular design.

Perovskite interface defect passivation with poly(ethylene oxide) for improving power conversion efficiency of the inverted solar cells.

Inverted perovskite solar cells (PSCs) attract researchers' attention for their potential application due to the low-temperature fabrication, negligible hysteresis and compatibility with multi-junction cells. However, the low-temperature fabricated perovskite films containing excessive undesired defects are not benefit for improving the performance of the inverted PSCs. In this work, we used a simple and effective passivation strategy that Poly(ethylene oxide) (PEO) polymer as an antisolvent additive to modify the perovskite films. The experiments and simulations have shown that the PEO polymer can effectively passivate the interface defects of the perovskite films. The defect passivation by PEO polymers suppressed non-radiative recombination, resulting in an increase in power conversion efficiency (PCE) of the inverted devices from 16.07% to 19.35%. In addition, the PCE of unencapsulated PSCs after PEO treatment maintains 97% of its original stored in a nitrogen atmosphere for 1000 h.

Progress, challenges, and perspectives on polymer substrates for emerging flexible solar cells: A holistic panoramic review

AbstractIn pursuit of a renewable, inexpensive, sustainable, and compact energy source to replace fossil fuels, solar photovoltaic devices have become an ideal alternative to meet human needs for environmentally friendly, affordable, and portable power sources. It is due to their excellent mechanical robustness and outstanding energy conversion efficiency. Concerning the increasing demand for flexible and wearable electronic devices with standalone power sources, much attention has been paid to photovoltaics' flexibility and lightweight developments. Along with high mechanical flexibility and lightweight, flexible photovoltaic devices have the advantages of conformability, bendability, wearability, moldability, and roll‐to‐roll processing into complex shapes that can produce niche products. Emerging solar cells, among other photovoltaic technologies, have been exalted for their high conversion efficiency, low cost, and ease of production, making them a viable new‐generation photovoltaic technology. The main commercialization choice for cutting‐edge solar cells is flexible dye‐sensitized and perovskite solar cells since they can be made using a roll‐to‐roll printing technique and are appropriate for mass manufacturing. More significantly, flexible evolving solar cells may be created on ultrathin and light substrates to fulfill the demands of the developing flexible electronics industry and discover uses that are not possible with traditional photovoltaic technology. In any flexible device, the substrate is a backbone on which further materials rely. A flexible substrate reduces the installation and transportation charges, thereby reducing the system price and increasing power conversion efficiency. In this review, we comprehensively assess relevant materials suitable for making flexible photovoltaic devices. Several flexible substrate materials, including ultra‐thin glass, metal foils, and various types of polymer materials, have been considered. For conducting materials, transparent conducting oxides, metal nanowires/grids, carbon nanomaterials, and conducting polymers have also been comprehended. Progress on various flexible foils, fabrication and stability issues, current challenges, and solutions to those challenges of using conductive polymer substrate is endorsed and reviewed in detail. The originality of this holistic study lies in its ability to offer a thorough overview of recent advancements in flexible dye‐sensitized and perovskite solar cells on polymer substrates, which is conceivable and worthy as a roadmap for future research work.