Layer For Perovskite Solar Cells Research Articles

Enhanced optoelectronic characteristics of La-doped ZnO and its compatibility with Cs-doped MAPbI3 perovskite absorber material

Abstract The present study investigates the structural, electrical and optical characteristics of pristine and lanthanum (La)-doped zinc oxide electron transport layers (ETLs) fabricated by the sol gel method and their compatibility with Cs0.10MA0.90Pb(I0.9Br0.10)3 absorber layer for perovskite solar cells. All the ETLs were deposited under same deposition conditions, with the only difference in La percentage in the precursor solutions, ranging from 0 to 6%. X-ray diffraction (XRD) analysis demonstrated the presence of crystalline ZnO thin films and the absence of any impurity phases after La-doping. The calculated crystallite size, determined using Scherrer’s equation, increased from 11.13 to 21.76 nm after the introduction of dopant. The doping with 4% La led to the decrease in the optical bandgap from 3.32 eV of pristine ZnO to 3.23 eV. SEM analysis revealed better morphology of perovskite/4% La:ZnO specimen, which facilitated the absorbance and reduced the charge carrier recombination. It also exhibited superior resilience towards moisture and humidity which will eventually contribute to the development of more stable and efficient planar perovskite solar cells (PCSs).

Synthesis and Characterization of TiO2 Nanorods for Efficient Electronic Transport Layer of Perovskite Solar Cells

Synthesis and Characterization of TiO2 Nanorods for Efficient Electronic Transport Layer of Perovskite Solar Cells

2,2'-Bipyridyl-4,4'-Dicarboxylic Acid Modified Buried Interface of High-Performance Perovskite Solar Cells.

The regulation of interfaces remains a critical and challenging aspect in the pursuit of highly efficient and stable perovskite solar cells (PSCs). Here, 2,2'-bipyridyl-4,4'-dicarboxylic acid (HBPDC) is incorporated as an interfacial layer between SnO2 and perovskite layers in PSCs. The two carboxylic acid moieties on HBPDC bind to SnO2 through esterification, while its nitrogen atoms, possessing lone electron pairs, interact with uncoordinated lead (Pb2+) atoms through Lewis acid-base interactions. This dual functionality enables simultaneous passivation of surface defects on both the SnO2 and buried perovskite layers. In addition, the electron-deficient nature of HBPDC enhances interfacial energy band alignment and facilitates electron transfer from the perovskite to SnO2. Furthermore, the incorporation of HBPDC strengthens the interfacial adhesion, improving mechanical reliability. As a result, the PSCs exhibited an impressive power conversion efficiency (PCE) of 25.41% under standard AM 1.5G conditions, along with remarkable environmental stability.

2,2′‐Bipyridyl‐4,4′‐Dicarboxylic Acid Modified Buried Interface of High‐Performance Perovskite Solar Cells

The regulation of interfaces remains a critical and challenging aspect in the pursuit of highly efficient and stable perovskite solar cells (PSCs). Here, 2,2′‐bipyridyl‐4,4′‐dicarboxylic acid (HBPDC) is incorporated as an interfacial layer between SnO2 and perovskite layers in PSCs. The two carboxylic acid moieties on HBPDC bind to SnO2 through esterification, while its nitrogen atoms, possessing lone electron pairs, interact with uncoordinated lead (Pb2+) atoms through Lewis acid‐base interactions. This dual functionality enables simultaneous passivation of surface defects on both the SnO2 and buried perovskite layers. In addition, the electron‐deficient nature of HBPDC enhances interfacial energy band alignment and facilitates electron transfer from the perovskite to SnO2. Furthermore, the incorporation of HBPDC strengthens the interfacial adhesion, improving mechanical reliability. As a result, the PSCs exhibited an impressive power conversion efficiency (PCE) of 25.41% under standard AM 1.5G conditions, along with remarkable environmental stability.

Synthesis and scalable process for fabrication of Perovskite Solar Cells using organic and inorganic hole transport materials

The Organic Inorganic Lead Iodide perovskite material has emerged as a pioneer in being an active material for third-generation solar cells. Apart from the synthesis, the scalable mechanism which is being used for the deposition process, greatly influences the performance of the cell owing to its impact on the morphology, uniform thickness, and interface between two functional layers. This study briefly discusses the various deposition processes involved in assembling the layers of perovskite solar cells (PSC). Hole transport materials (HTM) are a crucial part of the PSC providing efficient transport of the charge carriers. However, the effect of organic and inorganic HTMs is highly pronounced in the PSCs. This study also discusses the effect of organic and inorganic HTM on the stability and efficiency of the sandwich-structured PSC.

Reaction Dynamics between Formamidinium Lead Iodide and Copper Oxide.

Copper oxide (CuOx) has been announced as a very promising hole-transporting layer for perovskite solar cells. However, in our previous work, we have shown that once a formamidinium lead triiodide (FAPI) perovskite is spin-coated on a spray-coated cuprous oxide (Cu2O) substrate, the Cu2O diffuses into and reacts with the FAPI film. In order to verify if the degradation products are related to the oxidation state of CuOx and/or its preparation method, in this work, we first prepared CuOx films by thermal oxidation at temperatures ranging from 120 to 300 °C. While increasing the process temperature, a transformation from copper I (Cu2O) to copper II (CuO) oxidation states was observed. For both oxidation states of copper, FAPI perovskite degradation was found; however, some alterations in the reaction products were noticed. In contrast to our expectations, the introduction of an ultrathin plasma-enhanced atomic layer deposited Al2O3 layer in between both films only partially blocked the CuOx migration into the FAPI film. It can be concluded that regardless of the chemical composition and/or preparation method of CuOx, the overlayered FAPI film gets decomposed. In order to use CuOx as a hole-transporting layer in solar cells, new strategies must be developed to limit these unwanted chemical reactions.

Buried interface management for FAPbI3-based perovskite solar cells via multifunctional benzothiadiazole derivatives

Attaining high efficiency in perovskite solar cells (PSCs) often necessitates effective interfacial passivation, which poses challenges, especially concerning the buried interface due to the dissolution of passivation agents during perovskite deposition. In this work, we report a multifunctional modification strategy by introducing the variations of benzothiadiazole (BTD) derivatives to function as interface-modified layers in PSCs. This buried interface modification mitigates oxygen vacancies on the SnO2 surface and fine-tunes the energy level of the electron transport layer, resulting in an improved alignment with the FAPbI3 layer. Furthermore, the introduced BTD derivatives led to the improved crystallinity of FAPbI3 films as well as suppressed the non-radiative recombination losses through passivating the interfacial defects. Consequently, a device with modified SnO2 exhibited an enhanced power conversion efficiency (PCE) of 25.04% along with an improved long-term device stability.

Optimizing electron transport layers for high-efficiency perovskite solar cells using impedance spectroscopy

The best interface for a perovskite solar cell is designed to facilitate effective charge transport to achieve a high-power conversion efficiency. Tin dioxide (SnO2) is widely recognized as an electron transport material for perovskite solar cells, offering advantages such as low hysteresis, low defect concentration, and low fabrication temperature. However, the low conduction band edge of SnO2 restricts the built-in potential of the solar cell device. In this study, we designed a double layer of electron transport by applying zinc oxide (ZnO) on SnO2 to improve the electron transport properties in perovskite solar cells. The bilayer of electron transport enhances the interfaces between the perovskite and the electron transport layer, leading to an improvement in the efficiency and stability of solar cell devices up to 11.71 % compared to a single SnO2 layer device with a PCE of 9.06 %. The introduction of ZnO reduces charge recombination, resulting in a lower recombination resistance (Rrec). Also, charge transfer resistance (Rct) of ZnO/SnO2 increased to 16.6KΩ compared to a single SnO2 layer device with a Rct of 5.29KΩ. Our findings provide valuable insights into the design of electron transport layers for perovskite solar cells and highlight the importance of electrochemical impedance spectroscopy in understanding the dynamic processes that govern their performance.

Reduced graphene oxide as the electron transport layer in perovskite solar cell: effect on the photovoltaic performance

Reduced graphene oxide as the electron transport layer in perovskite solar cell: effect on the photovoltaic performance

Enhancing the Performance of Nanocrystalline SnO2 for Solar Cells through Photonic Curing Using Impedance Spectroscopy Analysis.

Wide-bandgap tin oxide (SnO2) thin-films are frequently used as an electron-transporting layers in perovskite solar cells due to their superior thermal and environmental stabilities. However, its crystallization by conventional thermal methods typically requires high temperatures and long periods of time. These post-processing conditions severely limit the choice of substrates and reduce the large-scale manufacturing capabilities. This work describes the intense-pulsed-light-induced crystallization of SnO2 thin-films using only 500 μs of exposure time. The thin-films' properties are investigated using both impedance spectroscopy and photoconductivity characteristic measurements. A Nyquist plot analysis establishes that the process parameters have a significant impact on the electronic and ionic behaviors of the SnO2 films. Most importantly, we demonstrate that light-induced crystallization yields improved topography and excellent electrical properties through enhanced charge transfer, improved interfacial morphology, and better ohmic contact compared to thermally annealed (TA) SnO2 films.

Tin-Lead Perovskite Solar Cells with Preferred Crystal Orientation by Buried Interface Approach.

Mixed tin-lead perovskite solar cells (PSCs) have garnered much attention for their ideal bandgap and high environmental research value. However, poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS), widely used as a hole transport layer (HTL) for Sn-Pb PSCs, results in unsatisfactory power conversion efficiency (PCE) and long-term stability of PSCs due to its acidity and moisture absorption. A synergistic strategy by incorporating histidine (HIS) into the PEDOT: PSS HTL is applied to simultaneously regulate the nucleation and crystallization of perovskite (PVK). HIS neutralizes the acidity of PEDOT: PSS and enhances conductivity. Especially, the coordination of the C═N and -COO- functional groups in the HIS molecule with Sn2+ and Pb2+ induces vertical growth of PVK film, resulting in the release of residual surface stress. Additionally, this strategy also optimizes the energy level alignment between the perovskite layer and the HTL, which improves charge extraction and transport. With these cooperative effects, the PCE of Sn-Pb PSCs reaches 21.46% (1 sun, AM1.5), maintaining excellent stability under a nitrogen atmosphere. Hence, the buried interface approach exhibits the potential for achieving high-performance and stable Sn-Pb PSCs.

Unveiling the potential of FASnI3 solar cells through advanced charge transport materials: A SCAPS-1D perspective

As demand grows for efficient and affordable photovoltaic technology, investigating alternative materials becomes crucial. Tin-based perovskite has a low bandgap, great optoelectronic properties, and higher carrier mobility. It has become an interesting absorber layer for perovskite solar cells (PSCs). However, improving their device performance presents challenges. Copper-based hole transport materials (HTM) and zinc-based electron transport materials (ETM) offer low cost, easy fabrication, and high electrical conductivity. This research analyzes the impacts of these transport materials on the FASnI3 absorber layer using numerical modeling in SCAPS-1D. Through simulation analysis, the study thoroughly examines the effect of these materials on PSC performance parameters such as QE curve, layer thickness, defect density, interface defect, and doping concentration. Moreover, this study identifies the most efficient PSC configurations, achieving good performance by ITO/ZnSe/FASnI3/Cu2O/Au with aVoc of 2.05 V, Jsc of 29.316 mA/cm2, FF of 53.37 %, and power conversion efficiency (PCE) of 32.13 %, providing valuable insights in optimizing FASnI3 solar cells and advancing next-generation solar energy conversion technologies.

Effect of lanthanum doped SnO2 on the performance of mixed-cation mixed-halide perovskite layer

Perovskite solar cells (PSCs) have attracted significant attention due to their higher efficiencies and lower fabrication costs. But for the better performance of PSCs, a high-quality electron transport layer (ETL) is crucial. Various ETLs have been employed and among them Tin (IV) oxide (SnO2) has emerged as a promising candidate for electron selective layer in PSCs due to its superior optical and electrical characteristics. However, there is still improvement needed in terms of poor surface morphology and conductivities of SnO2. When SnO2 is used in conjunction with absorber layer in ambient conditions, stability, and charge carrier recombinations at SnO2/perovskite interface remains a serious challenge as well. This study presents the doping of lanthanum (La III), a rare earth element, into SnO2 ETLs to improve the quality and performance of the perovskite layer deposited on top of ETL in ambient condition. With the optimized 4% La (III) doping, SnO2 ETLs become more crystalline with lower parasitic light absorption and surface morphology improves significantly. The improvement in morphology due to doping facilitates larger crystal growth of perovskite in ambient environment. Moreover, Photoluminescence reveals that with optimized level of doping, interfacial charge recombinations are significantly mitigated ensuring smooth injection of electrons into ETL because of superior perovskite film quality. The mixed-cation mixed-halide perovskite film deposited on 4% La:SnO2 ETL show better resistance towards moisture ingress and will substantially contribute to develop long-life of planar PSCs.

Key features of perovskite solar cells operando stabilization with ionic liquid choline cinnamate

The ionic liquid choline cinnamate was applied for the first time as a defect passivator in light-absorbing layers of perovskite solar cells (PSCs). It was found that bulk passivation with an addition of 0.5% ionic liquid notably enhances the photothermal stability of PSCs, while surface passivation leads to the opposite effect with the loss of device stability, due to the complex origin of the influence of choline cinnamate on the defect structure and microstructure of hybrid halide perovskites.

Self‐Healing Optical Structures for Light‐Trapping in Perovskite Solar Cells

AbstractSelf‐healing transparent polymers are advantageous for various optoelectronic devices to improve resilience and durability. However, most of these materials have been applied only as flat films and do not address the need for optical structures that can manipulate light. Here optical microstructures embossed on a self‐healing polyurea film are presented which can autonomously recover from damage in ambient conditions. The polyurea film have a high optical transmittance above 90% and haze below 1.3%, and Young's modulus of 3.4 MPa. When applied as a protective light‐trapping layer for perovskite solar cells, the champion device shows improved short circuit current density from 23.7 to 25.0 mA·cm−2, and power conversion efficiency from 21.5% to 23.0%. Furthermore, the solar cell with the light‐trapping layer has improved impact resistance and can recover its performance after being scratched. It is envisioned that self‐healing optical structures can be realized for different geometries and materials in a range of optoelectronic applications to produce resilient and durable devices.

Optimizing ZnO as an electron transport layer in perovskite solar cells: Study on aluminum doping and thickness variation

Optimizing ZnO as an electron transport layer in perovskite solar cells: Study on aluminum doping and thickness variation

Advances in Top Transparent Electrodes by Physical Vapor Deposition for Buffer Layer‐Free Semitransparent Perovskite Solar Cells

The advancements in halide perovskite materials, celebrated for their exceptional optoelectronic properties, have not only led to a remarkable increase in the efficiency of perovskite solar cells (PSCs) but also opened avenues for the development of semitransparent devices. Such devices are ideally suited for integration into building facades and for use in tandem solar cell configurations. However, depositing transparent electrodes (TEs) on top of the charge transport layers in PSC poses significant challenges. Physical vapor deposition (PVD), commonly used in the industry to prepare transparent conducting oxides (TCOs) as TEs, can introduce plasma‐induced damage during the process, which decreases the efficiency of the final devices. While incorporating a buffer layer is the typical approach to mitigate plasma damage, it also increases the complexity and costs of solar cell fabrication. This perspective focuses on the developments of buffer‐free semitransparent PSCs. It highlights the shift away from the typical approach of incorporating a buffer layer. Through a comprehensive analysis of recent research, this work presents successful cases of direct TCO deposition onto transport layers, evaluates scalability and stability, and concludes with recommendations for optimizing PVD processes in the fabrication of buffer‐free PSCs.

Low-Cost, Scalable Fabrication of Multi-Dimensional Perovskite Solar Cells and Modules Assisted by Mechanical Scribing.

The performance and scalability of perovskite solar cells (PSCs) based on 3D formamidinium lead triiodide (FAPbI3) absorber are often hindered by defects at the surface and grain boundaries of the perovskite. To address this, the study demonstrates the use of pyrrolidinium iodide for the in situ formation of an energetically aligned 1D pyrrolidinium lead triiodide (PyPbI3) capping layer over the 3D FAbI3 perovskite. The thermodynamically stable PyPbI3 perovskitoids, formed through cation exchange reactions, effectively reduce surface and grain boundary defects in the FAPbI3 perovskite. In addition to improved phase stability, the resulting 1D/3D perovskite film forms a cascade energy band alignment with the other functional layers in PSCs, enabling a barrier-free interfacial charge transport. With a maximum power conversion efficiency (PCE) of ≈23.1% and ≈20.7% at active areas of 0.09 and 1.05 cm2, respectively, the 1D/3D PSCs demonstrate excellent performance and scalability. Leveraging this improved scalability, the study has successfully developed a mechanically-scribed 1D/3D perovskite mini-module with an unprecedentedly high PCE of ≈20.6% and a total power output of ≈270mW at an active area of ≈13.0 cm2. The 1D/3D multi-dimensional perovskite film developed herein holds great promise for producing low-cost, high-performance perovskite photovoltaics at both the cell and module levels.

Oxide Derivatives of Nb2CTx MXene and Their Application as Electron Transport Layers in Perovskite Solar Cells: Unraveling the Oxidation Process and Functionalization.

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 Nb2CTx 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 Nb2CTx. Moreover, Nb2CTx 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 Nb2CTx 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 SnO2. This work unravels the oxidation dynamics of Nb2CTx and provides a promising approach to designing ETL by exploiting MXenes to their derivatives for photovoltaic technologies.

Screen-Assisted Self-Spreading of TiO2 Precursor Solution on FTO Substrates for High-Quality Electron Transport Layers in Perovskite Solar Cells.

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 TiO2 films on a rough fluorine-doped tin oxide (FTO) substrate as an ETL in planar PSCs. The TiO2 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 TiO2 film, confirming the effectiveness and reliability of the proposed method for the preparation of the TiO2 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.