Thin-film Perovskite Solar Cells Research Articles

Controllable Crystallization of Perovskite Films during the Blade-Coating Fabrication Process for Efficient and Stable Solar Cells

The scalable production of high-quality perovskite thin films is pivotal for the industrialization of perovskite thin film solar cells. Consequently, the solvent system employed for the fabrication of large-area perovskite films via coating processes has attracted significant attention. In this study, a solvent system utilizing a volatile solvent as the primary reagent has been developed to facilitate the rapid nucleation of volatile compounds. While adding the liquid Lewis base dimethylformamide (DMF) can help to improve the microstructure of perovskite films, its slow volatilization renders the crystal growth process uncontrollable. Based on the solvent system containing DMF and ethanol (EtOH), introducing a small amount of NH4Cl increases the proportion of the intermediate phase in the precursor films. This not only results in a controllable growth process for the perovskite crystals but also contributes to the improvement of the film microstructure. Under the simulated illumination (AM1.5, 1000 W/m2), the photoelectric conversion efficiency (PCE) of the inverted solar cells has been improved to 20.12%. Furthermore, after 500 hours of continuous illumination, the photovoltaic device can retain 95.6 % of the initial, indicating that the solvent system is suitable for the scalable fabrication of high-quality FAPbI3 thin films.

Milk Tea–Colored Perovskite Solar Cells Fabricated Through a Multilayer Film Design

This study presents the fabrication of perovskite thin-film solar cells (PTSCs) with adjustable colors, achieved through a multilayer film design. The multilayer film, comprising Au and indium-tin-oxide (ITO), functions as an adjusted color reflectance (ACR) multilayer film. When the ITO thickness is varied from 100 to 150 nm, the color of the PTSCs can be adjusted from lighter shades that resemble fresh milk tea to darker tones akin to caramel. The color changes that the ACR multilayer film induces correlate well with its reflectance response. Compared with traditional black-colored PTSCs, the milk tea–colored PTSCs maintain a power conversion efficiency of >12%. This achievement suggests the potential for fabricating PTSCs in various colors and patterns that are suitable for use in furnishings, accessories, and other applications.

Fabrication of efficient methylammonium-free perovskite thin-film solar cells without post-treatment and antisolvent

Recently, there has been a remarkable improvement in the efficiency of organic-inorganic perovskite solar cells (PSCs). However, the complexity of the fabrication process for these PSCs has increased due to the post-processing of the perovskite layer and the use of antisolvents, among others. In this investigation, a straightforward method for fabricating high-performance and CH3NH3+-free [CH(NH2)2PbI3]0.95[CsPbBr3]0.05 solar cells using fluorinated phosphoric acid passivating additives in combination with mixed solvents was presented. This study required neither post-treatment nor anti-solvent for solar cell fabrication. Fluorinated phosphoric acid was introduced into the perovskite layer, which then self-organized on the perovskite surface and exhibited a passivating effect. Planar PSCs fabricated at reduced temperatures without fluorinated phosphoric acid exhibited power conversion efficiencies (PCEs) of 19.9 % and 17.3 % during reverse and forward scanning, respectively. Conversely, PSCs fabricated with fluorinated phosphoric acid as an additive exhibited a remarkable PCE of 20.5 % without hysteresis and a stabilized power output of 20.4 %. This study will facilitate the fabrication of high-efficient PSCs in future research efforts, thereby promoting the advancement of these devices.

Exploration HTL-Free all inorganic mixed halide perovskite solar cells: effects of 4-ADPA passivation

The incredible PV performance of thin-film perovskite solar cells has garnered the attention of researchers. Mixed halide perovskite outweighs pure halide perovskite in its ability to optimize PV performance while performing material composition engineering. All inorganic mixed halide (AIMH) perovskite CsPbI2Br has shown stable performance against thermal variations. This study mainly highlights the performance of HTL (Hole transport layer) free, passivated solar cell structure with utilization of the SCAPS-1D simulator. The inclusion of passivation layer 4-ADPA(4-aminodiphenylamine) between active layer CsPbI2Br and the end electrode mitigates the occurrence of charge carrier recombination. The thickness of passivation layer 4-ADPA is optimized for the range 100 nm–1000 nm, and 100 nm is decided as the optimum width based on the evaluated PV performance of SnO2/CsPbI2Br/4-ADPA/anode. 4-ADPA layer with an optimum thickness of 100 nm, is embedded with a CsPbI2Br layer, and the performance of solar cell has been investigated under the collective impact of BDD (bulk defect density)/thickness of CsPbI2Br for the range (1012 cm−3 to 1018 cm−3)/(50 nm to 500 nm) respectively. Further, this study investigated the capacitance–voltage (C-V), Mott—Schottky (1/C2), and Nyquist plot (C-F) performance of solar cells under the influence of only BDD for two cell configurations (corresponding to maximum and minimum delivered PCE i.e., thickness/BDD is 200 nm/1012 cm−3 and 500 nm/1018 cm−3 respectively). The highest 13.27% of PCE is extracted from HTL-free, 4-ADPA passivated all inorganic PSC, at 200 nm/1012 cm−3 of thickness/BDD respectively. This technique encourages researchers to explore more cost-effective, HTL-free passivated solar cell structures.

Low-temperature influence on the properties and efficiency of thin-film perovskite solar cells fabricated by the PVco-D technique

The study discussed in this publication aimed to develop a perovskite solar cell adapted to operating conditions at reduced temperature and pressure and less than 1 μm thick. The physical vapor co-deposition technique was proposed and successfully used to create a solar cell structure with a thin layer of hybrid perovskite as an energy-collecting material. A comprehensive analysis of methylammonium lead iodide behavior in a wide temperature range from 10 K to 320 K was carried out to implement this project. The initial phase included assessing the degradation of the perovskite material layer after cooling to the temperature of liquid helium and then re-heating it to room temperature. Then, using spectroscopic techniques, the characteristics of the layers' optical and electrical properties were determined. The obtained results allowed the design of the complete structure of a thin-film perovskite cell, which was made using only the vacuum sublimation process. Simulations using the SCAPS-1D program and experimental results showed high agreement and allowed for obtaining an efficiency of approximately 18.5 % in the interested temperature range. Perovskite solar cell stability tests over six months confirmed the positive impact of the proposed technique for depositing the complete cell structure on its temporal stability. The research results are optimistic for the applications of perovskite cells in space.

An optical study on the enhanced light trapping performance of the perovskite solar cell using nanocone structure

Photon management strategies are crucial to improve the efficiency of perovskite thin film (PTF) solar cell. In this work, a nano-cone (NC) based 2D photonic nanostructure is designed and simulated aiming at achieve superior light trapping performance by introducing strong light scattering and interferences within perovskite active layer. Compared to the planar PTF solar cell, the NC nanostructured device with 45 degrees half apex angle obtains highest short-circuit current density, which improved over 20% from 15.00 mA/cm2 to 18.09 mA/cm2. This work offers an alternative design towards effective light trapping performance using 2D photonic nanostructure for PTF solar cell and could potentially be adopted as the nano-structuring strategy for the future perovskite solar cell industry.

Infrared-reflective ultrathin-metal-film-based transparent electrode with ultralow optical loss for high efficiency in solar cells

In this work we study in-depth the antireflection and filtering properties of ultrathin-metal-film-based transparent electrodes (MTEs) integrated in thin-film solar cells. Based on numerical optimization of the MTE design and the experimental characterization of thin-film perovskite solar cell (PSC) samples, we show that reflection in the visible spectrum can be strongly suppressed, in contrast to common belief (due to the compact metal layer). The optical loss of the optimized electrode (~ 2.9%), composed of a low-resistivity metal and an insulator, is significantly lower than that of a conventional transparent conductive oxide (TCO ~ 6.3%), thanks to the very high transmission of visible light within the cell (> 91%) and low thickness (< 70 nm), whereas the reflection of infrared light (~ 70%) improves by > 370%. To assess the application potentials, integrated current density > 25 mA/cm2, power conversion efficiency > 20%, combined with vastly reduced device heat load by 177.1 W/m2 was achieved in state-of-the-art PSCs. Our study aims to set the basis for a novel interpretation of composite electrodes/structures, such as TCO–metal–TCO, dielectric–metal–dielectric or insulator–metal–insulator, and hyperbolic metamaterials, in high-efficiency optoelectronic devices, such as solar cells, semi-transparent, and concentrated systems, and other electro-optical components including smart windows, light-emitting diodes, and displays.

Modeling for Efficiency Enhancement of Perovskite Thin-Film Solar Cell by Using Double-Absorber and Buffer Layers

Perovskite solar cells appear to be the most promising candidate for thin-film solar cells. In this work, double layer Perovskite solar cells were simulated using a SCAPS-1D simulator in which different thickness of the perovskite layers was used, a buffer layer of PEDOT:PSS was used, the effect of defect density in absorbing layers, the influence of doping in Spiro-OMeTAD as well as the effect of temperature is studied. With this proposed simulated model, the maximum efficiency of the perovskite solar cell reaches 28.22%. Hence this simulation work will provide handy information in fabricating perovskite solar cells to reasonably choose material parameters and to achieve high efficiency.

Solution slot-die coating perovskite film crystalline growth observed by &lt;i&gt;in situ&lt;/i&gt; GIWAXS/GISAXS

Solution method is an important means of fabricating optoelectronic devices. During the thin film sample preparation, organic or inorganic perovskite semiconductor material usually needs to be finished in a glove box. However, most of the traditional experimental characterizations under the air environment, it is hard to reflect the reality of the structure and performance between film and device, therefore it is urgently needed to solve the microstructure evolutions of these semiconductor films based on &lt;i&gt;in situ&lt;/i&gt; real-time representation technique. In this work, we report a synchrotron-based grazing incidence wide and small-angle scattering (GIWAXS and GISAXS) &lt;i&gt;in situ&lt;/i&gt; real-time observation technique combined with a mini glove box, thereby realizing the standard glove box environment (H&lt;sub&gt;2&lt;/sub&gt;O, O&lt;sub&gt;2&lt;/sub&gt; content all reached below 1×10&lt;sup&gt;–6&lt;/sup&gt;) under remote control film spin coating or slot-die preparation and various sample post-processing. Meanwhile, this technique can real-time monitor the microstructure and morphology evolution of semiconductor film during fabrication. Based on the &lt;i&gt;in situ&lt;/i&gt; device and GIWAXS, SnO&lt;sub&gt;2&lt;/sub&gt; ETL interface induced perovskite growth crystallization process shows that CQDs additive can result in three-dimensional perovskite, with the random orientation growth changing into highly ordered vertical orientation, meanwhile can effectively restrain the low-dimensional perovskite domain formation, helping to reveal the film microstructure transformation of inner driving force and providing the perovskite device preparation process optimized with experimental and theoretical basis. The conversion efficiency of large-area fully flexible three-dimensional perovskite thin film solar cells prepared by the roll-to-roll total solution slit coating method is increased to 5.23% (the area of a single device is ~15 cm&lt;sup&gt;2&lt;/sup&gt;). Therefore, using the &lt;i&gt;in situ&lt;/i&gt; synchrotron-based glove box device, the microstructure evolution and the associated device preparation conditions of perovskite and organic semiconductor thin films can be controlled, and the thin film growth interface characteristics and film quality can be further controlled, which is the key technology to control the optimization process conditions of semiconductor thin films and devices.

Improving photoluminescence properties and reducing recombination of CsPbBr3 perovskite through lithium doping.

This study investigates the impact of lithium doping on the structural and photophysical properties of spin-coated CsPbBr3 perovskite thin films. The deposited films display a pristine structure, preferentially growing along the (220) direction, and exhibit high-quality green photoluminescence at around 530 nm. The doping leads to an improvement in the optical properties of the films, as evidenced by a stronger photoluminescence (PL) intensity compared to undoped CsPbBr3, particularly at temperatures below 200 K. The increase in PL intensity suggests a decrease in defects and surface passivation. Additionally, the decrease in the power-law exponent β from 1.6 to 1.0 indicates a reduction in non-radiative recombination, likely due to trap states filling with free electrons induced by the doping. Overall, doping with lithium reduces non-radiative recombination, fills trap states, and reduces band tail/activation energy, leading to improved optoelectronic properties of the films. This investigation provides insights into the photophysical properties of the Li-CsPbBr3 absorber layer and the recombination mechanism, and helps to unravel new methods for the development of high-stability, high-performance perovskite thin-film solar cells and optoelectronic devices.

Numerical Simulation of Lead-Free Tin and Germanium Based All Perovskite Tandem Solar Cell

The ability to customize the materials bandgaps makes perovskite solar cells a promising candidate for hybrid-tandem applications. This allows them to effectively utilize parts of the solar spectrum that silicon-based solar cells cannot efficiently capture, resulting in higher absorption coefficients. However, there is a lack of research on lead-free all-perovskite tandem solar cells, and secondary data on materials is limited. One of the main challenges in previous studies is the high cost and solid structure of traditional silicon-based solar cells, which require significant storage space. Additionally, lead-based perovskite solar cells pose environmental concerns due to their water solubility and potential harmful effects upon consumption. To address these issues, thin-film perovskite solar cells with liquid solvents are employed in the solar cell design. Lead is replaced with germanium and tin-based perovskites, which exhibit comparable photovoltaic performance to silicon. In the present work, the OghmaNano simulation tool was utilized to conduct numerical simulation of the perovskite design. The perovskite solar cell layers were structured as follows: FTO/ZnO/MAGeI3/Spiro-OMeTAD/FAMASnGeI3/Cu2O/Au. The variables considered included optimum layer thicknesses and bandgaps, as well as the most suitable materials for the ETL and HTL, aiming to obtain the highest efficiency. Based on the simulation results, the proposed perovskite structure shows remarkable photovoltaic parameters. The Voc was measured at 0.84 V Jsc of 16.1 mA/cm2, FF of 0.825, and PCE that reached 11.12%. This project contributes to future research on materials for the ETL and HTL of lead-free, tin and germanium based APTSCs.

On performance of thin-film meso-structured perovskite solar cell through experimental analysis and device simulation

In the last few years, there has been an unprecedented progress in the increase of the power conversion efficiency of perovskite solar cells. Evidently, further advances in the efficiency of these devices will depend on the constraints imposed by the optical and electronic properties of their constituents. Quite apparently during the manufacturing process of a solar cell, there is an inevitable variation in the thicknesses of various functional layers, which affects the optoelectronic characteristics of the final sample. In this work, a possible strategy of the analysis of the solar cell performance is suggested, based on statistically averaging procedure of experimental data. We present a case study, in which the optoelectronic properties of the meso-structured perovskite solar cell (with a mesoporous TiO2 layer) are analyzed within the method providing a deeper understanding of the device operation. This method enables an assessment of the overall quality of the device, pointing pathways towards the maximum efficiency design of a perovskite solar cell by material properties tuning.

Tungsten dopant incorporation for bandgap and type engineering of perovskite crystals

Organic–inorganic hybrid halide perovskites have shown to be viable semiconductor materials, as the absorber layer of solar cells. Unfortunately, the polycrystalline qualities of perovskite films result in nonuniform coverage or a high recombination rate, which weakens the photoelectric capabilities of thin films. Here, the pure and tungsten (W)-doped methylammonium lead bromide (CH3NH3PbBr3 or MAPbBr3) films are deposited to FTO-glass substrates using the sol–gel spin coating method. The W-doping causes the nucleation and crystallization processes, which then have an impact on the film’s characteristics. It is discovered that the introduction of tungsten metal significantly enhances the quality of the perovskite film, resulting in larger grain sizes, lower band gap energy, and shorter recombination lifetimes, increasing the power conversion efficiency of perovskite thin film solar cells.

Screen-Printing Technology for Scale Manufacturing of Perovskite Solar Cells.

As a key contender in the field of photovoltaics, third-generation thin-film perovskite solar cells (PSCs) have gained significant research and investment interest due to their superior power conversion efficiency (PCE) and great potential for large-scale production. For commercialization consideration, low-cost and scalable fabrication is of primary importance for PSCs, and the development of the applicable film-forming techniques that meet the above requirements plays a key role. Currently, large-area perovskite films are mainly produced by printing techniques, such as slot-die coating, inkjet printing, blade coating, and screen-printing. Among these techniques, screen printing offers a high degree of functional layer compatibility, pattern design flexibility, and large-scale ability, showing great promise. In this work, the advanced progress on applying screen-printing technology in fabricating PSCs from technique fundamentals to practical applications is presented. The fundamentals of screen-printing technique are introduced and the state-of-the-art studies on screen-printing different functional layers in PSCs and the control strategies to realize fully screen-printed PSCs are summarized. Moreover, the current challenges and opportunities faced by screen-printed perovskite devices are discussed. This work highlights the critical significance of high throughput screen-printing technology in accelerating the commercialization course of PSCs products.

Methods for improving the stability of perovskite materials and their conversion efficiency

he research on perovskite thin film solar cells has made great progress in recent years and is believed to be a material with enormous potential for development. However, problems like relatively poor stability, environmental unfriendliness and low large-area photoelectric conversion efficiency remain to solve. Its large-scale production is still a long way off. This study introduces the recent progress of the perovskite materials for perovskite solar cells and reviews the three ways of improving the stability and photoelectric conversion efficiency of perovskite materials for solar cells, including dye sensitization, doping and graphene oxidation. Diverse dyes for sensitization of perovskite materials are listed, and their mechanics are briefly introduced. The principles of how doping and graphene oxidation improve the stability and photoelectric conversion efficiency of perovskite materials are also described in this manuscript. Finally, based on those methods, suggestions for the future development of perovskite materials for solar cells are provided.

Device simulation of CH3NH3PbI3-xClx based mixed halide perovskite thin film solar cells

Perovskite solar cells are an emerging area of study in photovoltaics research due to their low cost fabrication and high efficiency. In this paper, the numerical simulation of FTO/CdS/CH3NH3PbI3-xClx/CuI/Au device performance was investigated using solar cell capacitance simulator (SCAPS-1D). Here, mixed halide perovskite, Chloride (Cl) doped methyl ammonium lead iodide (CH3NH3PbI3-xClx), is used as perovskite light absorber layer due to good thermal stability, film quality and tunable bandgap property. In this present solar cell configuration CdS is used as buffer layer and CuI as hole transport layer (HTL). The effect of absorber layer thickness, operating temperature and different HTL’s were also analyzed on device performance. By varying the thickness of the absorber layer from 0.1 to 1.0 µm,the optimum thickness was found at 0.7 µm. In addition to this different HTL’s CuI, Spiro-OMeTAD and Cu2O were used in simulation and CuI gives best results compared to others. With optimized parameters, the proposed device achieves a PCE of 27.19%, FF of 87.88%, JSC of 23.86 mA/cm2 and VOC of 1.29 V. These optimized results will be used for the fabrication of an CH3NH3PbI3-xClx perovskite thin film solar cell.

Towards High-Efficiency Photon Trapping in Thin-Film Perovskite Solar Cells Using Etched Fractal Metadevices.

Reflective loss is one of the main factors contributing to power conversion efficiency limitation in thin-film perovskite solar cells. This issue has been tackled through several approaches, such as anti-reflective coatings, surface texturing, or superficial light-trapping metastructures. We report detailed simulation-based investigations on the photon trapping capabilities of a standard Methylammonium Lead Iodide (MAPbI3) solar cell, with its top layer conveniently designed as a fractal metadevice, to reach a reflection value R<0.1 in the visible domain. Our results show that, under certain architecture configurations, reflection values below 0.1 are obtained throughout the visible domain. This represents a net improvement when compared to the 0.25 reflection yielded by a reference MAPbI3 having a plane surface, under identical simulation conditions. We also present the minimum architectural requirements of the metadevice by comparing it to simpler structures of the same family and performing a comparative study. Furthermore, the designed metadevice presents low power dissipation and exhibits approximately similar behavior regardless of the incident polarization angle. As a result, the proposed system is a viable candidate for being a standard requirement in obtaining high-efficiency perovskite solar cells.

The surface chemistry of ionic liquid-treated CsPbBr3 quantum dots.

The power conversion efficiencies of lead halide perovskite thin film solar cells have surged in the short time since their inception. Compounds, such as ionic liquids (ILs), have been explored as chemical additives and interface modifiers in perovskite solar cells, contributing to the rapid increase in cell efficiencies. However, due to the small surface area-to-volume ratio of the large grained polycrystalline halide perovskite films, an atomistic understanding of the interaction between ILs and perovskite surfaces is limited. Here, we use quantum dots (QDs) to study the coordinative surface interaction between phosphonium-based ILs and CsPbBr3. When native oleylammonium oleate ligands are exchanged off the QD surface with the phosphonium cation as well as the IL anion, a threefold increase in photoluminescent quantum yield of as-synthesized QDs is observed. The CsPbBr3 QD structure, shape, and size remain unchanged after ligand exchange, indicating only a surface ligand interaction at approximately equimolar additions of the IL. Increased concentrations of the IL lead to a disadvantageous phase change and a concomitant decrease in photoluminescent quantum yields. Valuable information regarding the coordinative interaction between certain ILs and lead halide perovskites has been elucidated and can be used for informed pairing of beneficial combinations of IL cations and anions.

Improved Optical Efficiencies of Perovskite Thin Film Solar Cells by Randomly Distributed Ag Nanoparticles

Improved Optical Efficiencies of Perovskite Thin Film Solar Cells by Randomly Distributed Ag Nanoparticles

Multilayer conformal structural perovskite solar cells design for light trapping enhancement

Thin film perovskite solar cells (PSCs) have insufficient light utilization due to thickness limitation. Structural design of thin film PSCs can effectively enhance the property of light trapping and thereby improve the photocurrent density. In this work, both the thickness of perovskite layer and front Indium Tin Oxides (ITO) layer for classical PSCs was firstly optimized. 22.4% of light absorption enhancement can be achieved. Then, we proposed four different types of multilayer conformal structures PSCs consisting of hemisphere, cylinder, inverted pyramid and cone structures. Compared with the planner PSCs, the optimized hemispherical multilayer conformal structure (HMCS) PSCs can further enhance the light absorption by 12.3% and obtain the highest photocurrent density of 23.82 mA/cm−2. The photonic interaction between the structure and incident wavelength is examined and discussed. The presented method and multilayer conformal structures can be used to design the light absorption enhancement for a variety of PSCs.