Bandgap Perovskite Research Articles

Investigation strain effects on the electronic, optical, and output performance of the novel inorganic halide perovskite Sr3SbI3 solar cell

Inorganic perovskite materials have drawn more interest in solar technology because of their outstanding structural, optical, and electrical features. Utilizing first-principles density-functional theory, this work sought to determine how compressive and tensile strain affected the structural, optical, and electrical properties of Sr3SbI3, an inorganic cubic perovskite (FP-DFT). A direct bandgap of 1.307/1.95 eV was detected with PBE/HSE method at the point in the unstrained planar Sr3SbI3 molecule. But when the relativistic spin-orbital coupling (SOC) effect was taken into consideration, the bandgap of Sr3SbI3 perovskite dropped to 0.862 eV Additionally, the structure's bandgap showed a tendency to decrease under compressive pressure and slightly increase under tensile strain. According to the optical parameters, including dielectric functions, absorption coefficient, reflectivity, and electron loss functions, the band characteristics suggested that the material had substantial absorption capabilities in the visible area. The dielectric constant spikes of Sr3SbI3 moved towards lower photon energy (redshift) during compressive strain, however, the material showed an increase in photon energy changing behavior under tensile strain (blueshift). Finally, the photovoltaic (PV) performance of novel Sr3SbI3 absorber-based cell structures with SnS2 as Electron Transport Layer (ETL) was systematically investigated at varying compressive and tensile strain using SCAPS-1D simulator. The maximum power conversion efficiency (PCE) was found 29.91 % with JSC of 46.22 mA/cm2, FF of 79.50 %, VOC of 0.8139 V for maximum 4 % compressive strain. Therefore, the strain-dependent electronic and optical properties of Sr3SbI3 studied here would facilitate its future use in the design of photovoltaic cells and optoelectronics.

Predicting band gaps of ABN3 perovskites: an account from machine learning and first-principle DFT studies.

The present paper is primarily focused on predicting the band gaps of nitride perovskites from machine learning (ML) models. The ML models have been framed from the feature descriptors and band gap values of 1563 inorganic nitride perovskites having formation energies <-0.026 eV and band gaps ranging from ∼1.0 to 3.1 eV. Four supervised ML models such as multi-layer perceptron (MLP), gradient boosted decision tree (GBDT), support vector regression (SVR) and random forest regression (RFR) have been considered to predict the band gaps of the said systems. The accuracy of each model has been tested from mean absolute error, root-mean-square error and determination coefficient R2 values. The bivariate plots between the predicted and input band gaps of the compounds for both the training and test datasets have also been estimated. Additionally, two ABN3-type nitride perovskites CeBN3 (B = Mo, W) have been selected and their electronic band structures and optoelectronic properties have been studied from density functional theory (DFT) calculations. The band gap values of the said compounds have been estimated from DFT calculations at PBE, HSE06, G0W0@PBE, G0W0@HSE06 level of theories. The present study will be helpful in exploring the ML models in predicting the band gaps of nitride perovskites which in turn may bear potential applications in photovoltaic cells and optical luminescent devices.

Selective reactivity-assisted sacrificial additive coating for surface passivation of wide bandgap perovskite solar cells with cesium tetrafluoroborate

A novel method, named “selective reactivity-assisted sacrificial additive coating”, allowed the BF4− from the sacrificial additive to react selectively with the Cs+ from the perovskite, forming CsBF4 to passivate the A-site vacancy on the surface.

Effect of gamma-rays on recombination dynamics and defect concentration in a wide bandgap perovskite

Effect of gamma-rays on recombination dynamics and defect concentration in a wide bandgap perovskite

Self-assembly construction of a homojunction of Sn–Pb perovskite using an antioxidant for all-perovskite tandem solar cells with improved efficiency and stability

Self-assembly construction of a homojunction with antioxidant encapsulation for efficient and stable narrow bandgap perovskite solar cells and all-perovskite tandem solar cells.

Host–Guest Complexation in Wide Bandgap Perovskite Solar Cells

Host–Guest Complexation in Wide Bandgap Perovskite Solar Cells

All-perovskite tandem solar cells: from fundamentals to technological progress.

Organic-inorganic perovskite materials have gradually progressed from single-junction solar cells to tandem (double) or even multi-junction (triple-junction) solar cells as all-perovskite tandem solar cells (APTSCs). Perovskites have numerous advantages: (1) tunable optical bandgaps, (2) low-cost, e.g. via solution-processing, inexpensive precursors, and compatibility with many thin-film processing technologies, (3) scalability and lightweight, and (4) eco-friendliness related to low CO2 emission. However, APTSCs face challenges regarding stability caused by Sn2+ oxidation in narrow bandgap perovskites, low performance due to V oc deficit in the wide bandgap range, non-standardisation of charge recombination layers, and challenging thin-film deposition as each layer must be nearly perfectly homogenous. Here, we discuss the fundamentals of APTSCs and technological progress in constructing each layer of the all-perovskite stacks. Furthermore, the theoretical power conversion efficiency (PCE) limitation of APTSCs is discussed using simulations.

Unraveling the relationship between the phenethylammonium-induced 2D phase on the perovskite surface and inverted wide bandgap perovskite solar cell performance

We studied the impact of phenethylammonium chloride on PIN-structured wide bandgap perovskite solar cells. Elimination of the 2D phase results in a champion efficiency of 20.61% and a VOC loss of only 410 mV with hysteresis-free J–V curves.

First-principles and machine learning investigation on A4BX6 halide perovskites

The A4BX6 molecular halide perovskites have received attention owing to their interesting optoelectronic properties at the molecular scale; however, a comprehensive dataset of their atomic structures and electronic properties and associated data-driven investigation are still unavailable now, which makes it difficult for inverse materials design for semiconductor applications (e.g. wide band gap semiconductor). In this manuscript, we employ data-driven methods to predict band gaps of A4BX6 molecular halide perovskites via machine learning. A large virtual design database including 246 904 A4BX6 perovskite samples is predicted via machine learning, based on the model trained using 2740 first-principles results of A4BX6 molecular halide perovskites. In addition, symbolic regression-based machine learning is employed to identify more physically intuitive descriptors based on the starting first-principles dataset of A4BX6 molecular halide perovskites. In addition, different ranking methods are employed to offer a comprehensive feature importance analysis for the halide perovskite materials. This study highlights the efficacy of machine learning-assisted compositional design of A4BX6 perovskites, and the multi-dimensional database established here is valuable for future experimental validation toward perovskite-based wide band gap semiconductor materials.

Threshold bandgap of lead halide hybrid perovskites for making stable single crystal by NIR laser trapping

The remarkable optoelectronic properties of hybrid halide perovskites position them as pivotal materials for the next generation of electronic devices, LEDs, lasers, and solar cells, potentially revolutionizing these technological domains. In this study, we harness the capabilities of contemporary laser trapping technology—a non-contact method for manipulating particles—to elucidate the conditions necessary for stable perovskite crystal formation. Using a 1064 nm near-infrared (NIR) continuous-wave (CW) laser, commonly selected for trapping experiments, we establish the threshold bandgap essential for the stable crystallization of MAPbX3 perovskite crystals. Our research reveals that MAPbI3, with a bandgap of 1.59 eV, undergoes rapid explosive crystallization when subjected to the 1064 nm laser, making it unsuitable for stable crystal growth. In contrast, MAPbBr3 with a bandgap of 2.26 eV forms stable single crystals within 6 min at the air-solution interface, when exposed to the same 1064 nm NIR laser at 1.0 W output power. Notably, a minor reduction in bandgap to 2.23 eV in the mixed halide MAPbBr2.75I0.25 results in an abrupt transition to explosive crystallization. These findings introduce a novel insight into the bandgap dependency for the crystallization process, delineating a threshold bandgap of 2.26 eV for MAPbBr3, below which the crystal growth becomes unstable under a 1064 nm laser. The study provides a significant advancement in the field by defining the precise bandgap necessary for the formation of robust, stable perovskite crystals using laser trapping techniques. This threshold bandgap knowledge is crucial for developing controlled synthesis protocols for perovskites, optimizing their optoelectronic properties for application in modern technologies. Moreover, the investigation suggests that to achieve stable crystallization of perovskites with a bandgap below 2.26 eV, laser trapping with wavelengths longer than 1064 nm may be required, opening new avenues for material processing and device fabrication.

Rationalizing Performance Losses of Wide Bandgap Perovskite Solar Cells Evident in Data from the Perovskite Database

AbstractMetal halide perovskites (MHPs) have become a widely studied class of semiconductors for various optoelectronic devices. The possibility to tune their bandgap (Eg) over a broad spectral range from 1.2 eV to 3 eV by compositional engineering makes them particularly attractive for light emitting devices and multi‐junction solar cells. In this metadata study, data from Peer‐reviewed publications available in the Perovskite Database (www.perovskitedatabase.com) is used to evaluate the current state of Eg tuning in wide Eg MHP semiconductors. Recent literature on wide Eg MHP semiconductors is examined and the data is extracted and uploaded onto the Perovskite Database. Beyond describing recent highlights and scientific breakthroughs, general trends are drawn from 45,000 individual experimental datasets of MHP solar cell devices. The historical evolution of MHP solar cells is recapitulated, and general conclusions are drawn about the current limits of device performance. Three dominant causes are identified and discussed for the degradation of performance relative to the Shockley‐Queisser (SQ) model's theoretical limit for single‐junction solar cells: 1) energetically mismatched selective transport materials for wide Eg MHPs, 2) lower optoelectronic quality of wide Eg MHP absorbers, and 3) dynamically evolving compositional heterogeneity due to light‐induced phase segregation phenomena.

A Generic Strategy to Stabilize Wide Bandgap Perovskites for Efficient Tandem Solar Cells.

Efficient wide bandgap (WBG) perovskite solar cells (PSCs) are essential for fully maximizing the potential of tandem solar cells. However, these cells currently face challenges such as high photovoltage losses and the presence of phase segregation, which impede the attainment of their expected efficiency and stability. Herein, the root cause of halide segregation is investigated, uncovering a close association with the presence of locally aggregated lead iodide (PbI2 ), particularly at the perovskite/C60 interface. Kelvin-probe atomic force microscopy results indicate that the remaining PbI2 at the interface leads to potential electrical differences between the domain surface and boundaries, which drives the formation of halide segregation. By reacting the surface PbI2 residue with ethanediamine dihydroiodide (EDAI2 ) at proper temperature, it is possible to effectively mitigate the phase segregation. By applying this surface reaction strategy in WBG inverted cells, a notable improvement of ≈100mV is achieved in photovoltage over a wide range of WBG cells (1.67-1.78eV), resulting in a champion efficiency of 23.1% (certified 22.95%) for 1.67eV cells and 19.7% (certified 18.81%) for 1.75eV cells. Furthermore, efficiency of 26.1% is demonstrated in a monolithic all-perovskite tandem cell.

Deciphering Reaction Products in Formamidine-Based Perovskites with Methylammonium Chloride Additive.

The fabrication of formamidinium lead iodide (FAPbI3) perovskite solar cells (PSCs) involves the addition of methylammonium chloride (MACl) to promote low-temperature α-phase formation and grain growth. However, as the added MACl deprotonates and volatilizes into methylamine (MA0) and HCl for removal, MA0 can chemically interact with formamidinium (FA+), forming methyl formamidinium (MFA+) as a byproduct. Despite its significance, the chemical interactions among FAPbI3 perovskites, MACl additives, and their byproducts remain poorly understood. Our findings reveal that the FA+ and MA0 reaction primarily yields a mixture of cis/trans-N-methyl formamidinium iodide (MFAI) isomers, with cis-MFAI prevailing as the dominant species. Moreover, MFAI subsequently reacts with PbI2 to yield fully formed cis-MFAPbI3 2H-phase perovskite. We elucidated the effects of MFAI on the crystal growth, phase stability, and band gap of formamidine-based perovskites through the growth of single crystals. This research offers valuable insights into the role of these byproducts in influencing the efficiency and long-term stability of future PSCs.

Correlating Carrier Dynamics with Performance in Perovskite Solar Cells

Advancing the efficiency of perovskite solar cells (PSCs) critically depends on suppressing non‐radiative recombination at perovskite‐related interfaces and within the perovskite layer. A comprehensive understanding of carrier dynamic within PSCs is pivotal for promoting their efficiencies and facilitating more flexible design options for both perovskite and transport layers. Herein, the intrinsic mechanisms and device physics of PSCs are delved into, with a specific focus on investigating the variation of electron and hole mobilities and their effects on device performance. Through a rigorous photoelectric simulation, it is confirmed that the impact of performance of PSCs on electron or hole mobility primarily depends on the direction of illumination. For n–i–p PSCs, high hole mobility is favorable for the device performance, whereas for p–i–n PSCs, elevated electron mobility proves advantageous. Notably, these findings remain applicable across a large range of transport layers and perovskite bandgaps, although exceptions may arise when the perovskite layer undergoes specific doping. Additionally, it is discovered that high carrier mobility contributes to the reduction of both carrier and ion accumulation, thereby effectively suppressing hysteresis behavior. In this work, valuable insights into the significance and mechanisms of carrier mobility in PSCs are provided, offering essential guidance for fabricating high‐efficiency PSCs.

Minimizing Interfacial Recombination in 1.8eVTriple-Halide Perovskites for 27.5% Efficient All-Perovskite Tandems.

All-perovskite tandem solar cells show great potential to enable the highest performance at reasonable costs for a viable market entry in the near future. In particular, wide-bandgap (WBG) perovskites with higher open-circuit voltage (VOC ) are essential to further improve the tandem solar cells' performance. Here, a new 1.8eV bandgap triple-halide perovskite composition in conjunction with a piperazinium iodide (PI) surface treatment is developed. With structural analysis, it is found that the PI modifies the surface through a reduction of excess lead iodide in the perovskite and additionally penetrates the bulk. Constant light-induced magneto-transport measurements are applied to separately resolve charge carrier properties of electrons and holes. These measurements reveal a reduced deep trap state density, and improved steady-state carrier lifetime (factor 2.6) and diffusion lengths (factor 1.6). As a result, WBG PSCs achieve 1.36V VOC , reaching 90% of the radiative limit. Combined with a 1.26eV narrow bandgap (NBG) perovskite with a rubidium iodide additive, this enables a tandem cell with a certified scan efficiency of 27.5%.

Host–Guest Complexation in Wide Bandgap Perovskite Solar Cells

Wide‐bandgap hybrid halide perovskites are increasingly relevant in the fabrication of tandem solar cells. However, their efficiency and stability during operation are still limited by several factors, among which ion migration at the interface with charge‐selective extraction layers is one of the most detrimental ones. Herein, a host–guest complexation strategy is employed to control interfacial ion migration by using dibenzo‐21‐crown‐7 in wide‐bandgap hybrid halide perovskites based on methylammonium lead bromide. The capacity of the crown ether is demonstrated that affect the performances and stabilities of MAPbBr3 solar cells. As a result, power conversion efficiencies of up to 5.9% are achieved with an open circuit voltage as high as 1.5 V, which is accompanied by stability over 300 h at 85 °C under nitrogen atmosphere, as well as more than 300 h at ambient temperature, maintaining ∼80% of initial performance. This provides a versatile strategy for wide‐bandgap photovoltaic devices.

A-site cation engineering of cesium and MAPb0.5Sn0.5I3 perovskite: the properties and optoelectronic performance analysis using DFT calculations

Here, the first-principle calculations with the density functional theory calculations with PBE exchange–correlation functional were employed in investigating the effect of Cesium in the properties and optoelectronic performance of MAPb0.5Sn0.5I3 perovskite using A-site cation engineering technique. The control and Cesium based perovskites were generated and computed through CASTEP analysis from Material studio to determine their properties as well as optoelectronic performance. The findings revealed an improved properties of Cesium added perovskite compared to control ones. However, above 15%Cesium, phase separation was seen which declined the quality of the perovskite films. Moreover, simulation results of perovskites added with Cesium to 15% have demonstrated to have an improved optoelectronic performance as well as thermal stability by maintaining about 76% compared to the control which can retain about 39% of their initial power conversion efficiency after 15 days of aging at 85 °C in the ambient condition. This research presents a viable approach to investigate the impact of cation composition tuning on band gap, which can be extended to other perovskites. Additionally, it offers a broad set of design guidelines prior experiments for attaining a targeted band gap and modifying perovskite crystallization to enhance the characteristics, thermal stability, and optoelectronic performance of perovskite solar cells.

Identification of High-Reliability Regions of Machine Learning Predictions Based on Materials Chemistry.

Progress in the application of machine learning (ML) methods to materials design is hindered by the lack of understanding of the reliability of ML predictions, in particular, for the application of ML to small data sets often found in materials science. Using ML prediction for transparent conductor oxide formation energy and band gap, dilute solute diffusion, and perovskite formation energy, band gap, and lattice parameter as examples, we demonstrate that (1) construction of a convex hull in feature space that encloses accurately predicted systems can be used to identify regions in feature space for which ML predictions are highly reliable; (2) analysis of the systems enclosed by the convex hull can be used to extract physical understanding; and (3) materials that satisfy all well-known chemical and physical principles that make a material physically reasonable are likely to be similar and show strong relationships between the properties of interest and the standard features used in ML. We also show that similar to the composition-structure-property relationships, inclusion in the ML training data set of materials from classes with different chemical properties will not be beneficial for the accuracy of ML prediction and that reliable results likely will be obtained by ML model for narrow classes of similar materials even in the case where the ML model will show large errors on the data set consisting of several classes of materials.

Exciton Chirality Transfer Empowers Self-Triggered Spin-Polarized Amplified Spontaneous Emission from 1D-Anchoring-3D Perovskites.

Spin-polarized lasers, arising from stimulated emission of imbalanced spin populations, play a vital role in spin-optoelectronics.It is usually tackled by external spin injection, inevitably suffering from additional losses across the barriers from injection sources to gain materials. Herein, spin-polarized coherent light emission is self-triggered from the 1D-anchoring-3D perovskites, where the imbalanced populations in achiral 3D perovskites are endowed with the spin selectivity of exciton chirality (EC) underpinned by chiral 1D perovskites. Efficient transfer of EC is enabled by rapid energy transfer, thereby creating an imbalance of the spin population of excited states. Stimulated emission of such populations brings self-triggered spin-polarized amplified spontaneous emission in the composite perovskites, yielding a higher degree of polarization (DOP) than that based on optical spin injection into bare achiral 3D perovskites. Chemical diversity of composite perovskites not only enables to adjust band gap for broadband output of spin-polarized lightsignals but also promises to manipulate radiative decay and spin relaxation toward remarkably increased DOP. These results highlight the importance of EC transfer mechanism for spin-polarized lasing and represent a crucial step toward the development of chiral-spintronics.

An in-depth analysis of how strain impacts the electronic, optical, and output performance of the Ca3NI3 novel inorganic halide perovskite

The incredible optical, structural, and electronic behaviors of inorganic type perovskite compounds have recently attracted considerable interest in the area of solar innovation. This study thoroughly investigated how it affects both tensile and compressive strain on the physical, optical, as well as electronic behaviors that exist in the cubic inorganic Ca3NI3 perovskite using FP-DFT, or first-principles density functional theory. The planar structure of the unstrained Ca3NI3 molecule at the location revealed a direct bandgap of 1.077 eV/1.61 eV using the PBE/HSE technique. The bandgap of the Ca3NI3 perovskite was reduced to 0.827 eV by taking into account the impact of spin-orbit coupling (SOC). Additionally, the bandgap of the framework showed a tendency to decrease under compressive pressure (0.932 eV in −4% strain) and slightly increase under tensile strain (1.187 eV in +4 % strain). According to an analysis of the band characteristics, visible light can be significantly absorbed by the substance as shown by optical parameters like absorption coefficients, reflectivity, dielectric functions, and electron loss functions. The static dielectric constant, ε1(0) of Ca3NI3 is 6.96, the location of the initial critical point in, ɛ2(ω) is 1.07 eV, the energy range of the large absorption peak is 7.2–7.6 eV, peak location of loss function is 8.7–9.3 eV and reflectivity at 0 eV is 4.8. The Ca3NI3 dielectric constant spikes shifted to lower photon energy as a result of a redshift brought on by an increase in compressive strain. On the other hand, as tensile strain increased, the material showed a blue shift, resulting in an increase in photon energy. Finally, using the SCAPS-1D simulator, the photovoltaic (PV) performance of novel Ca3NI3 absorber-based cell architectures with SnS2 as the Electron Transport Layer (ETL) was thoroughly examined under varied compressive and tensile strain. The greatest power conversion efficiency (PCE) was found to be 31.35 % with JSC of 39.43 mA/cm2, FF of 85.47 %, VOC of 0.9301 V for maximum 4 % tensile strain. These findings suggest that the Ca3NI3 perovskite may be suitable for solar cell applications including energy production and light management in near future.