CsPbI2Br Perovskite Solar Cells Research Articles

Optimization of Inverted All-Inorganic CsPbI3 and CsPbI2Br Perovskite Solar Cells by SCAPS-1D Simulation

Perovskite solar cells (PSCs) have substantially increased their power conversion efficiency (PCE) to more than 25% in recent years. However, the instability of these devices is still a strong obstacle for their commercial applications. Recently, all-inorganic PSCs based on CsPbI3 and CsPbI2Br as the perovskite layer have shown enhanced long-term stability, which makes them potential candidates for commercialization. Currently, all-inorganic PSCs with inverted p-i-n configuration have not yet reached the high efficiency achieved in the normal n-i-p structure. However, the inverted p-i-n architecture has recently drawn attention of researchers because it is more suitable to prepare tandem solar cells. In this work, a theoretical study of inverted p-i-n all-inorganic PSCs based on CsPbI3 and CsPbI2Br as the perovskite layer was carried out using SCAPS-1D software (ver. 3.3.09). The performance of different architectures of PSC was examined and compared by means of numerical simulations using various inorganic materials as the hole transport layer (HTL) and the electron transport layer (ETL). The results reveal that CuI and ZnO are the most suitable as HTL and ETL, respectively. In addition, the performance of the devices was significantly improved by optimizing the hole mobility in CuI as well as the thickness, doping density, and defect density in the absorber layer. Maximum efficiencies of 26.5% and 20.6% were obtained under optimized conditions for the inverted all-inorganic CsPbI3- and CsPbI2Br-based PSCs, respectively. These results indicate that further improvements in the performance of such devices are still possible.

Photo-rechargeable all-solid-state lithium − sulfur batteries based on perovskite indoor photovoltaic modules

Photovoltaic technologies for indoor energy harvesting have attracted considerable attention because of the unique power requirements associated with the Internet of Things. However, intermittent power supplies, low light intensities, and security issues are barriers to the development of indoor photovoltaic technology. Herein, we demonstrate an all-solid-state photo-rechargeable battery system for indoor energy harvesting and storage based on an all-inorganic CsPbI2Br perovskite solar cell module and an all-solid-state lithium − sulfur battery. This energy conversion and storage unit exhibits an excellent overall energy conversion and storage efficiency of 11.2 % under LED illumination, as well as a high electrochemical storage capacity of 1585.3 mAh g−1. Moreover, the unit also shows good safety and stability after 200 h of photo-charge and galvanostatic discharge cycles due to the thermal stability of the solid-state CsPbI2Br perovskite and sulfide electrolyte. Even in the thermal aging tests at 60°C and 90°C, the photo-rechargeable battery still delivers superior high and steady performance for 200 h.

High-performance carbon-based all-inorganic CsPbI2Br perovskite solar cells via ethylammonium iodide and phenethylammonium iodide synergistic passivation

Hole transporting layer (HTL)-free, carbon-based all-inorganic CsPbI 2 Br perovskite solar cells have attracted great attention with suitable band gap, excellent thermal stability, low manufacturing cost and simplified procedure processes. Focusing on issues including energy level match and contact between the carbon electrode and the perovskite layer that limit the device performance, passivation strategies are widely applied on the interfaces within perovskite solar cells. Herein, the effect of synergistic passivation of ethylammonium iodide (EAI) and phenethylammonium iodide (PEAI) on all-inorganic perovskite (CsPbI 2 Br) solar cells is studied for the first time. Results indicate that α-/δ-phase heterojunction and localized 2D/3D heterojunction formed on the CsPbI 2 Br film surface tend to reduce the trap density and promotes the energy level gradient arrangement. In addition, EA + ions enter into the lattice and passivate the bulk phase defects of perovskite. As a result, the synergistic passivated devices (active area 0.0706 cm 2 ) exhibit an increased PCE from 11.74% to 13.76% and a high fill factor (FF) of 80.32%, as well as promising long-term stability. • The α-/δ-phase heterojunction and localized 2D/3D heterojunction were constructed by EAI and PEAI synergistic passivation. • The synergistic passivation reduces the trap density and promotes the energy level gradient arrangement. • It achieves a champion PCE 13.76% with a high FF of 80.32% based on HTL-free carbon-based CsPbI 2 Br PSCs.

Efficiency Potential and Voltage Loss of Inorganic CsPbI2Br Perovskite Solar Cells

Inorganic perovskite solar cells show excellent thermal stability, but the reported power conversion efficiencies are still lower than for organic–inorganic perovskites. This is mainly caused by lower open‐circuit voltages (VOCs). Herein, the reasons for the low VOC in inorganic CsPbI2Br perovskite solar cells are investigated. Intensity‐dependent photoluminescence measurements for different layer stacks reveal that n–i–p and p–i–n CsPbI2Br solar cells exhibit a strong mismatch between quasi‐Fermi level splitting (QFLS) and VOC. Specifically, the CsPbI2Br p–i–n perovskite solar cell has a QFLS–e ·VOC mismatch of 179 meV, compared with 11 meV for a reference cell with an organic–inorganic perovskite of similar bandgap. On the other hand, this study shows that the CsPbI2Br films with a bandgap of 1.9 eV have a very low defect density, resulting in an efficiency potential of 20.3% with a MeO–2PACz hole‐transporting layer and 20.8% on compact TiO2. Using ultraviolet photoelectron spectroscopy measurements, energy level misalignment is identified as a possible reason for the QFLS–e ·VOC mismatch and strategies for overcoming this VOC limitation are discussed. This work highlights the need to control the interfacial energetics in inorganic perovskite solar cells, but also gives promise for high efficiencies once this issue is resolved.

Dual-passivation strategy on CsPbI2Br perovskite solar cells for reduced voltage deficit and enhanced stability

The notorious defects in the grain boundaries (GBs) and surfaces trigger serious nonradiative recombination and interfacial charge losses, concomitantly exacerbating the deterioration of photovoltaic performance and phase stability of CsPbI2Br perovskite solar cells. In this work, a comprehensive dual-passivation strategy enabled by formamidine salts (FADP) is developed to annihilate defects both inside the GBs and over the surface. It is shown that formamidinothiourea (FATU) additive could effectively modulate crystallization and afford to passivate both shallow-/deep-level defects at GBs, thereby endowing CsPbI2Br films with reduced lattice micro-strains and enlarged grains over 2 µm. Meanwhile, formamidinium bromine (FABr) post-treatment can efficiently heal the defective surface and realize cationic exchange with below CsPbI2Br films, forming a gradient band alignment at the CsPbI2Br/HTL interface. Profiting from ameliorated crystallization, inhibited GBs/surface charge recombination and facilitated hole transport ability, the novel FADP strategy substantially lifts the Voc from 1.22 V to 1.34 V, yielding a champion PCE of 16.74% with greatly reduced hysteresis. Coincidently, the unencapsulated FADP devices maintained 86.2% of initial PCE after aging at 25% RH for 40 days and 83.8% after 480 h aging under continuous illumination, which is pertinent to the inhibited defective region as well as Br-rich surface.

Enhanced performance of CsPbI2Br perovskite solar cell through improving the solubility of the components in precursor

As a key of the perovskite growth, the properties of precursor influence the quality of film greatly. Among many properties, the solubility of the solute determines whether crystal film can form or the film with high quality. Therefore, we chose the small organic molecule acetamide (AT) with functional groups NH2 and CO as additive to improve the solubility of the original component CsI and regulate the crystallization of CsPbI2Br perovskite. Different from the Lewis acid-base interaction occurred between the additives and PbI2 reported by many researches, the hydrogen bond formed between the NH2 in AT and the I in CsI in CsPbI2Br perovskite precursor improved the activity and solubility of CsI, the corresponding effects caused the components in precursor participated in the crystallization and stabilized the crystal structure. And which excellent addition reflected in the suppressed unstable δ phase generated during the crystallization. As a consequence, the Pb0 roots in halogen vacancies in control film was also eliminated after added the AT, and the nonstoichiometric ratio in annealed film was further eliminated. In final, the power conversion efficiency (PCE) increased from the 10.24 % for control solar cell to 13.36 % for modified solar cell, and the stability has also been greatly improved.

The CsPbI2Br Perovskite Solar Cell with High Open‐Circuit Voltage by Crystallization Optimization

All‐inorganic CsPbI2Br perovskite acquires affirmation in recent years by reason of the excellent balance between stability and power conversion efficiency (PCE), but its PCE is still inferior to the commercial application standard, of which inferiority roots from the uncontrolled crystallization and a mass of the imperfections. Herein, the crystallization is regulated by introducing a certain amount of lead acetate into the precursor, and the complex Pb(Ac)2 × DMSO × PbI2 forms in precursor. The Oswald crystal pattern changes into the 2D layered structure —3D cubic structure crystal pattern, and this transition process is delayed, and the complex in precursor is regarded as the 2D crystal growth template. And the iodine vacancy defects are passivated by the Ac−, and the PbO passivates the grain boundary defects, as proved by the photoluminescence spectrum and X‐ray photoelectron spectroscopy. The two effects work together improve the performance of the CsPbI2Br perovskite solar cells. The PCE increases from 9.78% to 13.73%, and the open‐circuit voltage increases from 1.23 to 1.32 V, which is one of the superior performances reported for the carbon‐based pure CsPbI2Br perovskite solar cells to date.

Stable High‐Efficiency CsPbI2Br Solar Cells by Designed Passivation Using Multifunctional 2D Perovskite

AbstractCsPbI2Br perovskite is known for its advantages over its organic‐inorganic hybrid counterpart including better thermal stability and appropriate bandgap for the front sub‐cell of tandem solar cell. However, its lower‐than‐satisfactory efficiency, problematic phase stability and sensitivity to moisture hinder its further advancement. Here, three kinds of glycine halides (Gly‐X: X = Cl, Br, and I) are strategically deigned to improve the performance of CsPbI2Br perovskite solar cells (PSCs). Systematic experimental and calculated results prove that a 2D/3D hybrid structure is formed, wherein the Gly‐X‐based 2D perovskite is mainly located at the CsPbI2Br grain boundaries, and the A‐sites of the 2D perovskite form strong bonds with the 3D perovskite to suppress ion migration by increasing its activation energy. As a result, a power conversion efficiency (PCE) of 17.26% was obtained with an open‐circuit voltage (VOC) of 1.33 V, which is among the best PCE values for the CsPbI2Br PSCs. In addition, the efficiency of encapsulated device decrease only by 14.1% after 340 h continuous illumination in ambient conditions, representing one of the most‐stable inorganic PSCs reported so far. This work provides important insights into designing passivating agents to address the issue of phase segregation for the development of highly stable perovskite optoelectronic devices.

Organic ionic plastic crystals: A promising additive for achieving efficient and stable CsPbI2Br perovskite solar cells

CsPbI2Br perovskite is a promising candidate for highly efficient photoactive materials. We firstly introduced an organic ionic plastic crystals additive, 1,1′-Spirobipyrrolidinium hexafluoride (SBP + PF6−), to increase the power conversion efficiency and improve the stability by adjusting the crystallization of the CsPbI2Br perovskite light-absorbing layer and passivating the pinhole defects at the grain boundary. The detailed results reveal that PF6− molecular anions can fill the vacancy in the X-site and passivate the interface defects. Moreover, SBP+ with high conductivity can be used to regulate A-site defects. The results show that the SBP + PF6− modified device exhibits a champion efficiency of 13.20%, enhanced by 19% than that of the control device. This work proposes not only a straightforward strategy to control the crystallization process in CsPbI2Br perovskite-based solar cells but also the functionality of organic ionic plastic crystals additive for chemical bonding and defects passivation to improve efficiency and stability.

Low temperature-processed stable and high-efficiency carbon-based CsPbI2Br perovskite solar cells by additive strategy

All-inorganic perovskite solar cells require high-temperature preparation processes, which severely hinders their further commercial development. Inorganic perovskite materials have a high crystallization barrier, so the crystallinity is poor under low temperature conditions, resulting in poor device performance. Therefore, it is an important challenge to develop an excellent low-temperature preparation process. In this paper, the crystallization kinetics of the CsPbI2Br perovskite film under low temperature conditions was studied, and it was found that the perovskite was not completely crystallized during low temperature crystallization, and PbI2 remained. The PbI2 residue not only caused the appearance of lead defects but also formed insoluble CsBr due to the insufficient reaction of the raw materials. Through the interaction between the organic molecules 3-Amino-3-(3-pyridyl)propionic Acid (PA) and PbI2, the crystallization reaction process can be effectively improved. Eliminating the residual PbI2 also effectively inhibited the precipitation of CsBr, thereby significantly improved the crystallinity of CsPbI2Br. Efficiencies of 10.95% are achieved for low-temperature-processed CsPbI2Br planar-architecture FTO/SnO2/CsPbI2Br/carbon, and the obtained device also showed good stability in the air.

Surface dipole affords high-performance carbon-based CsPbI2Br perovskite solar cells

All-inorganic carbon-based perovskite solar cells (C-PSCs) are an effective substitute for traditional organic–inorganic PSCs due to their excellent heat tolerance. However, the energy level mismatch between the inorganic perovskite and the carbon electrode leads to serious undesired charge recombination, which reduces photovoltaic performance of the devices. Here, we introduced 4-aminotetrahydropyran bromide (ATHPBr) as an electric dipole molecule to adjust the electronic state of the interface to cause a change in the work function (WF) and improve the extraction and collection of holes between the CsPbI2Br and the carbon electrode. The efficiency of the modified device increases from 12.78% to 14.50%, which is currently one of the highest reported efficiencies of all-inorganic C-PSCs. The device maintains 94% of the initial efficiency after 1200 h aging under a 15–20% relative humidity (RH) ambient condition at room temperature. Therefore, it is a novel and effective way for preparing highly efficient and stable all-inorganic C-PSCs.

Reversible degradation-assisted interface engineering via Cs4PbBr6 nanocrystals to boost the performance of CsPbI2Br perovskite solar cells

CsPbI2Br perovskites are promising candidates for photovoltaic applications owing to the trade-off between the optoelectronic properties and phase stability of cesium-based inorganic perovskites. However, the major shortcomings of CsPbI2Br perovskite solar cells (PSCs), namely energy loss and poor moisture resistance, still need to be addressed. In this work, reversible degradation-assisted decoration with Cs4PbBr6 nanocrystals (NCs) is used to passivate the perovskite/hole transporting material (HTM) interface. Moisture-induced Cs4PbBr6 decomposition products (CsPbBr3 and CsBr) and CsPbI2−xBr1+x (x > 0), generated as a result of halide anion exchange between CsPbI2Br and Cs4PbBr6 or its decomposition products, are found to improve the quality of the CsPbI2Br film and suppress the trap state density. In addition, the decoration achieves desirable energy-level alignments at the CsPbI2Br/HTM interface and raises the Fermi level of the CsPbI2Br film, thereby strengthening the built-in electric field between the perovskite and HTM. As a result, the optimized CsPbI2Br PSC has a champion efficiency of 15.52% with an open-circuit voltage of 1.30 V (mean value: 1.29 V). The unencapsulated CsPbI2Br film and device both exhibit high air stability (∼40% humidity), and the latter retains 90% of its initial efficiency after a 500 h aging test.

Gadolinium-incorporated CsPbI2Br for boosting efficiency and long-term stability of all-inorganic perovskite solar cells

All-inorganic CsPbI2Br perovskite solar cells (PSCs) have received extensive research interests recently. Nevertheless, their low efficiency and poor long-term stability are still obstacles for further commercial application. Herein, we demonstrate that high efficiency and exceptional long-term stability are realized by incorporating gadolinium(III) chloride (GdCl3) into the CsPbI2Br perovskite film. The incorporation of GdCl3 enhances the Goldschmidt tolerance factor of CsPbI2Br perovskite, yielding a dense perovskite film with small grains, thus the α-phase CsPbI2Br is remarkably stabilized. Additionally, it is found that the GdCl3-incorporated perovskite film achieves suppressed charge recombination and appropriate energy level alignment compared with the pristine CsPbI2Br film. The noticeable increment in efficiency from 14.01% (control PSC) to 16.24% is achieved for GdCl3-incorporated PSC. Moreover, the nonencapsulated GdCl3-incorporated PSC exhibits excellent environmental and thermal stability, remaining over 91% or 90% of the original efficiency after 1200 h aging at 40% relative humidity or 480 h heating at 85 °C in nitrogen glove box respectively. The encapsulated GdCl3-incorporated PSC presents an improved operational stability with over 88% of initial efficiency under maximum power point (MPP) tracking at 45 °C for 1000 h. This work presents an effective ion-incorporation approach for boosting efficiency and long-term stability of all-inorganic PSCs.

Unraveling the Mechanism of Ion-Migration Suppression by Interstitial Doping for Operationally Stable CsPbI2Br Perovskite Solar Cells

Unraveling the Mechanism of Ion-Migration Suppression by Interstitial Doping for Operationally Stable CsPbI₂Br Perovskite Solar Cells

Multistrategy Toward Highly Efficient and Stable CsPbI2Br Perovskite Solar Cells Based on Dopant‐Free Poly(3‐Hexylthiophene)

All‐inorganic perovskites have attracted substantial interest due to their outstanding thermal stability. However, the device performance is still inferior to the typical organic–inorganic counterparts because of the unsatisfying phase stability and defects of the inorganic perovskite films. Herein, a multistrategy to optimize CsPbI2Br perovskite solar cells (PSCs) based on dopant‐free poly(3‐hexylthiophene) (P3HT) by applying thienylmethylamine acetate additive to enhance the α phase stability and passivate the bulk defects of CsPbI2Br perovskite is successfully demonstrated, followed by implementing BTCIC‐4Cl interlayer at CsPbI2Br/P3HT interface, which can coordinate with both perovskite and P3HT to suppress the surface defects and promote the hole transport. Benefitting from these, a champion power conversion efficiency (PCE) of 16.3% is achieved, and the unencapsulated optimized device can retain 97% of the initial PCE after aging under N2 atmosphere at 85 °C for 530 h. This work opens up a new era of multistrategy for improving performance and stability of CsPbI2Br PSCs based on dopant‐free hole transport layer.

Organic Ionic Plastic Crystals: A Promising Additive for Achieving Efficient and Stable Cspbi2br Perovskite Solar Cells

Organic Ionic Plastic Crystals: A Promising Additive for Achieving Efficient and Stable Cspbi2br Perovskite Solar Cells

High-Efficiency Cspbi2br Perovskite Solar Cells (17.38%) with Over 83% Fill Factor by Synergistic Effects of a Multifunctional Additive

High-Efficiency Cspbi2br Perovskite Solar Cells (17.38%) with Over 83% Fill Factor by Synergistic Effects of a Multifunctional Additive

Htl-Free Carbon-Based Cspbi2br Perovskite Solar Cells with Efficiency Over 14% by Using Nickel Sulfide Nanoparticles Modification

Htl-Free Carbon-Based Cspbi2br Perovskite Solar Cells with Efficiency Over 14% by Using Nickel Sulfide Nanoparticles Modification

Dual-Passivation Strategy on Cspbi2br Perovskite Solar Cells for Reduced Voltage Deficit and Enhanced Stability

Dual-Passivation Strategy on Cspbi2br Perovskite Solar Cells for Reduced Voltage Deficit and Enhanced Stability

The synergistic effect of defect passivation and energy level adjustment for low-temperature carbon-based CsPbI2Br perovskite solar cells

Hydrophobic organic ammonium halide salts are used to passivate perovskite defects, adjust interfacial energy level alignments, and ultimately improve the efficiency and stability of low-temperature carbon-based CsPbI2Br perovskite solar cells.