Perovskite Research Articles

Designing an Efficient Lead-Free Perovskite Solar Cell through a Computational Method

Organometallic halide perovskite (PVK)-based solar cells (PSC) have gained significant popularity owing to their efficiency, adaptability, and versatility. However, the presence of lead in conventional PVK poses environmental risks and hinders effective commercialization. Although lead-free PVK solar cells have been developed, their conversion efficiency is limited due to intrinsic losses. To address this challenge, we present a simulation study focusing on methylammonium tin bromide (MASnBr3) as an alternative material. In our investigation, the MASnBr3 layers are strategically placed between a copper iodide (CuI)-based hole transporting material (HTM) and a zinc oxide (ZnO)-based electron transporting material (ETM). We optimize the active layer thickness, operating temperature, defect density analysis, and series resistances to assess device performance. Furthermore, we employ contour mapping, considering both thickness and defect density, for a detailed investigation. Our primary objective is to achieve unprecedented efficiency in lead-free MASnBr3-based PSCs. Remarkably, our study achieves the highest JSC (short-circuit current density) of 34.09 mA/cm2, VOC (open-circuit voltage) of 1.15 V, FF (fill factor) of 82.06%, and optimized conversion efficiency of 32.19%. These advancements in conversion efficiency pave the way for the development of lead-free PVK solar cells in the desired direction.

Integrated capture and solar-driven utilization of CO2 from flue gas and air

Integrated capture and solar-driven utilization of CO2 from flue gas and air

Reactive e-beam evaporated SnOx layer as an effective ETL for highly efficient spray-coated perovskite solar cells

The spray-coating deposition method can extend the use of perovskite solar modules to substrates with different shapes and curvatures that can be used in various parts of buildings and vehicles to maximize the use of solar energy. Due to the lack of centrifugal forces in this method, unlike spin-coating, the quality of the deposited perovskite layer highly depends on the wettability and uniformity of the under layer. In this project, the SnOx layer is deposited by the reactive electron beam evaporation method (re-SnOx) as an electron transport layer for the spray-coated Cs0.05FA0.81MA0.14PbI2.55Br0.45 layer. Results show that spray-coated perovskite (PSK) layers are significantly more uniform on re-SnOx layers compared to the spin-coated commercial nanoparticles of SnOx (np-SnOx) due to their excellent surface coverage and purity. The best efficiency of 20.8% is obtained for re-SnOx/spray-coated PSK. Surface passivation of spray-coated PSK with phenethylammonium iodide improves all photovoltaic properties, increases efficiency from an average of 17.9%–19.6%, and reduces the hysteresis index from an average of 0.3 to 0.09. This low-temperature structure can be fabricated on plastic substrates, as well.

Crystallization Process for High-Quality Cs0.15FA0.85PbI2.85Br0.15 Film Deposited via Simplified Sequential Vacuum Evaporation

Multiple-source thermal evaporation is emerging as an excellent technique to obtain perovskite (PVK) materials for solar cell applications due to its solvent-free processing, accurate control of stoichiometric ratio, and potential for scalability. Nevertheless, the currently reported layer-by-layer deposition approach is afflicted by long processing times caused by the multiple repetitions of thin films, which hinder industrial uptake. On the other hand, the coevaporation entails higher complexity due to the challenges of controlling the sublimation of multiple sources simultaneously. In this work, we propose a simplified approach consisting of a single-cycle deposition (SCD) of three thick precursor layers to obtain high-quality Cs0.15FA0.85PbI2.85Br0.15 (CsFAPbIBr) films. After annealing, the optimized PVK film exhibits comparable properties to the one deposited by multicycle deposition in terms of crystal structure, in-depth uniformity, and optoelectrical properties. Also, the formation and evolution of SCD PVK during annealing are investigated. We found that, in the competitive processes of precursor diffusion and reaction, the presence of cesium bromide can assist precursor mixing driven by the annealing treatment, demonstrating a reaction-limited process in the PVK conversion. With this simplified SCD approach, a PVK film is obtained with expected optical and opto-electronic properties, providing an appealing way for future thermally evaporated PVK device preparation.

Energy Yield Prediction of Bifacial Perovskite/Silicon Tandem Photovoltaic Modules

Bifacial perovskite (PVK)/crystalline silicon (c‐Si) tandem photovoltaic (PV) modules provide an effective strategy to further improve the efficiency and energy yield (EY) of c‐Si PV modules. In this work, the energy outputs of bifacial tandem PV modules under outdoor conditions are analyzed by combining optical modeling, one‐diode equivalent circuit model, module tilt angle, and meteorological data, and a detailed comparative study with bifacial silicon heterojunction (SHJ) PV modules is also performed. The bifacial PVK/c‐Si tandem modules exhibit higher EY in locations with strong direct normal irradiance regardless of the ground type with any albedo, while bifacial SHJ modules exhibit similar or even higher EY than tandem modules in locations with strong diffuse horizontal irradiance (DHI) such as Chengdu. Considering factors such as EY and levelized cost of electricity, Eg_PVK in the range of 1.58–1.62 eV is suitable for most application scenarios, while the deployment of bifacial SHJ PV modules is preferred in areas dominated by DHI, as represented by Chengdu. Herein, important implications for policy making in determining the cost‐effective type of PV modules are provided to generate renewable electricity.

Effects of Chemical Valences of Sulfur on the Performance of CsFAMA Perovskite Solar Cells.

The low electrical conductivity and the high surface defect density of the TiO2 electron transport layer (ETL) limit the quality of the following perovskite (PVK) layers and the power conversion efficiency (PCE) of corresponding perovskite solar cells (PSCs). Sulfur was reported as an effective element to passivate the TiO2 layer and improve the PCE of PSCs. In this work, we further investigate the effect of chemical valences of sulfur on the performance of TiO2/PVK interfaces, CsFAMA PVK layers, and solar cells using TiO2 ETL layers treated with Na2S, Na2S2O3, and Na2SO4, respectively. Experimental results show that the Na2S and Na2S2O3 interfacial layers can enlarge the grain size of PVK layers, reduce the defect density at the TiO2/PVK interface, and improve the device efficiency and stability. Meanwhile, the Na2SO4 interfacial layer leads to a smaller perovskite grain size and a slightly degraded TiO2/PVK interface and device performance. These results indicate that S2- can obviously improve the quality of TiO2 and PVK layers and TiO2/PVK interfaces, while SO42- has little effects, even negative effects, on PSCs. This work can deepen the understanding of the interaction between sulfur and the PVK layer and may inspire further progress in the surface passivation field.

Evaluation of Voltage-Matched 2T Multi-Junction Modules Based on Monte Carlo Ray Tracing

As Si single-junction technology is approaching its Shockley–Queisser theoretical limit, relevant efforts are being expended towards the development of multi-junction modules. In this work, we employ an optical model based on Monte Carlo ray tracing to compare four different multi-junction modules in a voltage-matched two-terminal (VM2T) configuration. In particular, we took into consideration the VM2T coupling of crystalline silicon cells with CuInxGa1-xSe2 (CIGS), CdTe, GaAs and perovskite (PVK) solar cells. We optimized the thicknesses of each layer in the top sub-module and determined the performance of VM2T modules in the Shockley–Queisser theoretical limit. We also considered the possibility of using modules in which the top Si surface is flat to determine the performance drop due to the absence of the texturization on the top Si surface. Moreover, we determined the optimal bandgap energy of PVK in a VM2T PVK/Si module as well as the highest efficiency achievable. Lastly, we show that when using state-of-the-art cells, the highest VM2T efficiency achievable for the considered materials is 34.2% under standard test conditions.

Buried modification with tetramethylammonium chloride to enhance the performance of perovskite solar cells with n-i-p structure

Intrinsic defects in the electron transport layer (ETL) and perovskite (PVK) layer, as well as energy level mismatch between the PVK and ETL, severely limit the device performance of perovskite solar cells (PSCs). Here, we introduced a multifunctional molecule (tetramethylammonium chloride, TMACl) as a passivator in the SnO2 ETL. During the annealing treatment, the defects in SnO2 ETL are suppressed by passivating the oxygen vacancies on the surface of SnO2. Moreover, the presence of TMACl enables the defects inevitably generated during the annealing process of PVK to be effectively passivated by the migrating TMA+ cations and Cl− anions. The characterization results further confirm that the surface modification of TMACl is more favorable for the suppression of interfacial recombination and the passivation of bulk and grain boundary defects of PVK compared to the bulk doping method. It is noteworthy that, compared with the pristine device (21.02%), the devices based on TMACl-doped SnO2 and TMACl-modified SnO2 ETLs obtained superior champion efficiencies of 22.71% and 23.08%, respectively. More importantly, the unencapsulated PSCs based on TMACl-modified SnO2 maintained 88% of their original efficiency during 35 days of storage in a humidity-controlled chamber with a relative humidity of 20–30%, demonstrating the passivation of SnO2 ETL using TMACl salts is an effective and promising approach to achieving high photovoltaic performances of PSCs.

Optical simulations and optimization of perovskite/CI(G)S tandem solar cells using the transfer matrix method

In this work we employ the transfer matrix method for the analysis of optical materials properties to simulate and optimize monolithic tandem solar cell devices based on CuIn1−x Ga x Se2, CI(G)S, and perovskite (PVK) absorbers. By finding models that fit well the experimental data of the CI(G)S solar cell, the semitransparent perovskite solar cell (PSC) and the PVK/CI(G)S monolithic tandem solar cell, we were able to perform a detailed optical loss analysis that allowed us to determine sources of parasitic absorption. We found better substitute materials for the transport layers to increase the power conversion efficiency and, in case of semitransparent PSCs, sub-bandgap transmittance. Our results set guidelines for the monolithic PVK/CI(G)S tandem solar cells development, predicting an achievable efficiency of 30%.

Influence of Al doping in zinc oxide electron transport layer for the degradation triple-cation-based organometal halide perovskite solar cells

Various strategies have been adapted to fabricate stable organic-inorganic hybrid perovskite (PVT) solar cells (PSCs). The triple-cation (CH3NH3+ (MA+), CH3(NH2)2+ (FA+), and Cs+) along with dual-anion (I− and Br−)-based PVT (TC-PVT) layer offers better stability than single cation-based PVTs. The deprivation of the PVT absorber is also influenced by the interface of the absorber with the charge transport layer (electron transport layer (ETL) and hole transport layer (HTL)). Here, the degradation of the TC-PVT coated on Al-doped zinc oxide (AZO) as well as FTO/AZO/TC-PVT/HTL structured PSC was examined for various Al to Zn molar ratio (RAl/Zn) of AZO. The PL decay study of FTO/AZO/TC-PVT revealed that the lowest degradation in the power (35.38%) was observed for the AZO with RAl/Zn of 5%. Furthermore, the PV cell parameters of the PSCs were analytically determined to explore the losses in the PSCs during degradation. The shunt resistance reduction was maximum (50.32%) for RAl/Zn = 10%, whereas, minimum shunt loss (7.33%) for RAl/Zn of 2%. The highest loss due to series resistance was observed for RAl/Zn of 0%. The changes in diode ideality factor (n) and reverse saturation current density (J0) were the smallest for RAl/Znof 10%.

Fullerene modification of WO3 electron transport layer toward high‐efficiency MA‐free perovskite solar cells with eliminated light‐soaking effect

AbstractIn perovskite solar cells (PSCs), the light‐soaking effect, which means device performance changes obviously under continuous light illumination, is potentially harmful to loaded devices as well as accurately assessing their efficiency. Herein, chemically stable tungsten trioxide (WO3) with high electron mobility is used as electron transport material in methylamine (MA)‐free PSCs. However, the light‐soaking effect is observed apparently in our devices. A fullerene derivative, C60 pyrrolidine Tris‐acid (CPTA), is introduced to modify the interface between WO3 and perovskite (PVK) layers, which can bond with WO3 and PVK simultaneously, leading to the passivation of the defect and the suppression of trap‐assisted nonradiative recombination. What is more, the introduction of CPTA can enhance the built‐in electric field between WO3 and PVK layers, thereby facilitating the electron extraction and inhibiting the carrier accumulation at the interface. Consequently, the light‐soaking effect of WO3‐based PSCs has been eliminated, and the power conversion efficiency has been boosted from 17.4% for control device to 20.5% for WO3/CPTA‐based PSC with enhanced stability. This study gives guidance for the design of interfacial molecules to eliminate the light‐soaking effect.

A perspective on the use of perovskite luminophores for solar windows

Perovskite (PRV) luminescent solar concentrators (LSCs) use PRV materials to concentrate and convert sunlight into electricity. LSCs are made up of a flat plate or sheet of glass or plastic that contains a layer of luminescent PRV material. When sunlight enters the LSC, the PRV material absorbs the light and emits it at a longer wavelength. This emitted light is then trapped inside the LSC by total internal reflection, and it travels to the edges of the plate where it is collected by photovoltaic (PV) solar cells (SCs). The use of PRV materials in LSCs offers several advantages over other materials. PRV materials are highly efficient at converting light into electricity. They are also flexible, low-cost, and easy to manufacture, making them a promising candidate for large-scale solar energy applications. However, PRV materials have some challenges preventing their adoption. They are sensitive to moisture or heat and can degrade quickly over time. This significantly limits their lifespan and stability. Research on PRV is mostly focused on making them more stable and durable, but finding ways to improve the manufacturing process to reduce costs and increase efficiency is also relevant. While the opportunities offered by PRV materials for the specific application to LCSs are certainly interesting, the challenges make the prospect of a commercial product very unlikely in the short term.

Highly Efficient and Stable Perovskite Solar Cells: Competitive Crystallization Strategy and Synergistic Passivation.

Defects of perovskite (PVK) films are one of the main obstacles to achieving high-performance perovskite solar cells (PSCs). Here, the authors fabricated highly efficient and stable PSCs by introducing prolinamide (ProA) into the PbI2 precursor solution, which improves the performance of PSCs by the competitive crystallization and efficient defect passivation of perovskite. The theoretical and experimental results indicate that ProA forms an adduct with PbI2 , competes with free I- to coordinate with Pb2+ , leads to the increase of the energy barrier of crystallization, and slows down the crystallization rate. Furthermore, the dual-site synergistic passivation of ProA is revealed by density functional theory (DFT) calculations and experimental results. ProA effectively reduces non-radiative recombination in the resultant films to improve the photovoltaic performance of PSCs. Notably, ProA-assisted PSCs achieve 24.61% power conversion efficiency (PCE) for the champion device and the stability of PSCs devices under ambient and thermal environments is improved.

Design guides for artificial photosynthetic devices consisting of voltage-matched perovskite/silicon tandem solar-cell modules and electrochemical reactor modules

We clarified the design guides for H2- and CO-producing artificial photosynthetic devices. The combination of a voltage-matched (VM) tandem solar-cell (SC) module and an electrochemical (EC) module was adopted. The parallel-connected top and bottom SC modules, in which multiple organic–inorganic hybrid perovskite (PVK) SCs with a bandgap of 1.7 eV and crystalline-silicon SCs were connected in series, respectively, powered the EC module consisting of series-connected multiple EC reactors. It was found that the design parameters of the series connection numbers must be optimized under slightly greater solar intensity and higher temperature than the average values to minimize the mismatch between the device operating voltage and SC maximal power voltage. This is in contrast to that the annual electricity production of the VM SC module coupled with a power conditioner is not sensitive to the optimization conditions. Increases in the bandgaps of the PVK SCs do not affect the annual production significantly.

Improving the charge carrier separation efficiency at the perovskite/carbon electrode interface in HTL-free carbon-based perovskite solar cells via physical polishing

Carbon-based perovskite solar cells (C-PSCs) are favored by researchers for their low cost and support for large-scale production. However, the particles precipitated on the surface of the perovskite (PVK) film can affect the fabrication and operation of C-PSC, such as disrupting the coating of C electrode film and producing defects that can aggravate the carrier recombination. Herein a reliable and efficient C-PSC is prepared by applying a physical polishing strategy. The compact interface contact and the larger Fermi level difference at the carbon-PVK (C/PVK) interface are achieved, resulting in a 21.4% increase in power conversion efficiency compared to that without polishing. A hole-transport-layer-free C-PSC with an efficiency of 12.2% is achieved, resulting from the reduction of PVK surface roughness and defects that cause non-radiative recombination. It is revealed that the physical polishing can reduce the root mean square roughness from 15.9 nm to 1.2 nm, facilitating the screen printing of the C electrode. The carrier lifetime of the PVK film also increases from 39.9 ns to 73.3 ns, which improves the photocurrent of the solar cell. We believe that the improved C/PVK interface contact will provide a solid foundation for the future large-scale commercial production of PSCs.

Interfacial Modification of Multifunctional Organic Ammonium Salt for PEDOT:PSS‐Based Inverted Perovskite Solar Cells

The performance of inverted perovskite solar cells (PSCs) is highly dependent on the surface properties of the hole‐transport layers (HTLs). Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most widely used HTLs due to its excellent properties. However, some drawbacks severely limit its application in PSCs. Herein, multifunctional bulk organic ammonium salts (BOASs) are deposited onto PEDOT:PSS films and used for interfacial modifications. The BOASs‐modified PEDOT:PSS has better energy‐level alignment with perovskite (PVK) than PEDOT:PSS, resulting in the suppressed voltage loss of PSCs. Depositing BOASs on top of the PSS isolates moisture to inhibit the ionization of sulfonic acid groups, which is beneficial to reduce the acidity and corrosiveness of PEDOT:PSS. In addition, the interfacial modification of BOASs can effectively enlarge the surface energy of PEDOT:PSS films and improve the morphology of the PVK layer. Therefore, the open‐circuit voltage and fill factor of the PSCs based on BOASs‐modified PEDOT:PSS are simultaneously increased to a maximum of 1.03 V and 73%, respectively, resulting in a champion device efficiency of 18.37%. The unencapsulated PSCs based on BOASs‐modified PEDOT:PSS remain more than 80% power conversion efficiency loss after 700 h of exposure to air.

Numerical investigation of toxic free perovskite solar cells for achieving high efficiency

Increasing efficiency, simple and inexpensive fabrication process and flexibility nature of organic metal halide perovskite (PVK) based solar cell has fascinated the researchers around the globe. However, Lead, a poisonous substance in PVK solar cell causes various issues which directly or indirectly impact the environment as well as the health of living things. It prevents the commercialization of PVK based solar cell. To overcome this, a number of lead-free perovskite solar cell has been designed and fabricated. But the conversion efficiency is still not up to par because of intrinsic losses. In order to improve the efficiency, a thorough theoretical investigation is required that can reveal the cause behind these losses. In this study a special PVK material named methylammonium tin iodide (MASnI3) is used in simulation platform to design a highly efficient organic lead-free solar cell. This study focuses on the optimization of active layer thickness, working temperature, capacitance-voltage (C-V), and impedance and defect density, as they plays major roles in determining the performance of toxic free organic PVK solar cell. The study confirms an high efficiency (η) of 24.22% at the optimized condition. Such high efficiency with an optimized structure can open a door for the commercialization of lead free PVK based solar cell.

Hybrid Perovskite-Based Wireless Integrated Device Exceeding a Solar to Hydrogen Conversion Efficiency of 11.

A wireless solar water splitting device provides a means to achieve an inexpensive and highly distributed solar-to-fuel system owing to its portability, flexible scale, and simple design. Here, a highly efficient hydrogen-generating artificial leaf is introduced, which is a wireless configuration for converting solar energy into chemical energy, by integrating ahybrid perovskite (PSK) as the light absorber with catalysts for electrochemical reaction. First, a single integrated photoelectrochemical photocathode, and a spatially decoupled hydrogen evolution reaction catalyst, are fabricated. A decoupled geometry is adopted to enable the physical protection of the PSK layer from the electrolyte, thus allowing excellent stability for over 85h. Additionally, an efficient dual photovoltaicmodule photocathode is fabricatedto produce sufficient photovoltage to drive water splitting reactions, as well as a high photocurrent to achieve the applied-bias photoconversion efficiency (13.5%). To investigate the overall water splitting performance, a NiFe-OH catalyst is employed, and the device with a wired configuration achieves a photocurrent density of 9.35mA cm-2 , corresponding to a solar to hydrogen (STH) efficiency of 11.5%. The device with a fully integrated wireless artificial leaf configuration exhibited a similar STH efficiency of over 11%, demonstrating the effectiveness of this cell design.

Deciphering the Relevance of Quantum Confinement in the Optoelectronics of CsPbBr3 Perovskite Nanostructures.

Perovskites (PVKs) have emerged as an exciting class of semiconducting materials owing to their magnificent photophysical properties and been used in solar cells, light-emitting diodes, photodetectors, etc. The growth of multidimensional nanostructures has revealed many exciting alterations in their optoelectronic properties compared to those of their bulk counterparts. In this work, we have spotlighted the influence of quantum confinement in CsPbBr3 PVKs like the quantum dot (PQD), nanoplatelet (PNPL), and nanorod (PNR) on their charge transfer (CT) dynamics with 1,4-naphthoquinone (NPQ). The energy band alignment facilitates the transfer of both electrons and holes in the PNPL to NPQ, enhancing its CT rate, while only electron transfer in the PQD and PNR diminishes CT. The tunneling current across a metal-nanostructure-metal junction for the PNPL is observed to be higher than others. The higher exciton binding energy in the PNPL results in efficient charge transport by enhancing the mobility of the excited-state carrier and its lifetime compared to those of the PNR and PQD.

Round-comb Fe2O3@SnO2 heterostructures enable efficient light harvesting and charge extraction for high-performance all-inorganic perovskite solar cells

The precise design of an electron transport layer (ETL) to improve the light-harvesting and quality of perovskite (PVK) film plays a crucial role in the photovoltaic performance of n-i-p perovskite solar cells (PSCs). In this work, a novel three-dimensional (3D) round-comb Fe2O3@SnO2 heterostructure composites with high conductivity and electron mobility induced by its Type-II band alignment and matched lattice spacing is prepared and employed as an efficient mesoporous ETL for all-inorganic CsPbBr3 PSCs. Arising from the multiple light scattering sites provided by the 3D round-comb structure, the diffuse reflectance of Fe2O3@SnO2 composites is increased to improve the light absorption of the deposited PVK film. Besides, the mesoporous Fe2O3@SnO2 ETL affords not only more active surface for sufficient exposure to the CsPbBr3 precursor solution but also a wettable surface to reduce the barrier for heterogeneous nucleation, which realizes the regulated growth of a high-quality PVK film with less undesired defect. Hence, both the light-harvesting capability, the photoelectrons transport and extraction are improved, and the charge recombination is restrained, delivering an optimized power conversion efficiency (PCE) of 10.23 % with a high short-circuit current density of 7.88 mA cm−2 for the c-TiO2/Fe2O3@SnO2 ETL based all-inorganic CsPbBr3 PSCs. Moreover, under lasting erosion at 25 °C and 85 % RH for 30 days and light-soaking (AM 1.5G) for 480 h in air atmosphere, the unencapsulated-device shows superiorly persistent durability.