Perovskite Absorber Research Articles

Surface reconstruction of wide-bandgap perovskites enables efficient perovskite/silicon tandem solar cells

Wide-bandgap perovskite solar cells (WBG-PSCs) are critical for developing perovskite/silicon tandem solar cells. The defect-rich surface of WBG-PSCs will lead to severe interfacial carrier loss and phase segregation, deteriorating the device’s performance. Herein, we develop a surface reconstruction method by removing the defect-rich crystal surface by nano-polishing and then passivating the newly exposed high-crystallinity surface. This method can refresh the perovskite/electron-transporter interface and release the residual lattice strain, improving the charge collection and inhibiting the ion migration of WBG perovskites. As a result, we can achieve certified efficiencies of 23.67% and 21.70% for opaque and semi-transparent PSCs via a 1.67-eV perovskite absorber. Moreover, we achieve four-terminal perovskite/silicon tandem solar cells with a certified efficiency of 33.10% on an aperture area of one square centimeter.

Electric-field-induced aging dynamics of triple-cation lead iodide perovskite at nanoscale

Herein, we report the nanoscale cations dynamics in Cs0.1MA0.15FA0.75PbI3 films during the electric-field-induced aging process using infrared scattering scanning near-field microscopy (IR s-SNOM) combined with a series of complementary analytical techniques such as PL-microscopy, SEM/EDX and ToF-SIMS. The revealed major field-induced aging pathways are related to the anodic oxidation of I− and the cathodic reduction of MA+ and FA+, which finally result in the depletion of organic species in the device channel and the formation of metallic lead. FA+ cations show significantly higher stability with respect to electrochemical reduction as compared to MA+ cations. Formamidinium cations are preserved on the surface of the near-cathode film area even after 40 days of the 1 V/μm field exposure, while MA+ cations demonstrate complete decomposition after 24 days. The obtained results demonstrate that IR s-SNOM represents a powerful technique for studying the spatially resolved field-induced degradation dynamics of hybrid perovskite absorbers and the identification of more promising materials resistant to the electric field.

Achieving Over 30% Efficiency Employing a Novel Double Absorber Solar Cell Configuration Integrating Ca3NCl3 and Ca3SbI3 Perovskites

Perovskites are particularly appealing solar absorber materials in the realm of photovoltaic (PV) technology due to their remarkable optical properties, low cost, increased efficiency, and lightweight design. This study proposes a structure that combines a double perovskite absorber layer (DPAL) of Ca3NCl3 and Ca3SbI3 with an electron transport layer (ETL) and hole transport layer (HTL) of CdS and CBTS via SCAPS-1D. Our research also demonstrated that the perovskite solar cell (PSC) with DPAL performs much better with the addition of HTL and is more efficient than single-layer PSCs. This paper thoroughly examines the effect of thickness, doping levels, and defect densities of each layer on electrical parameters like VOC, JSC, FF, and PCE. Additionally, it shows the J-V and QE characteristics and thoroughly examines the effects of temperature. With a DPAL of 24.43%, two solar cells built around a single absorber have achieved their maximum efficiency of 17.19% and 18.07%, respectively. Using CBTS HTL with Al/FTO/CdS/dual absorber (Ca3SbI3/Ca3NCl3)/CBTS/Ni structure, this study achieves an optimized efficiency of up to 30.22% with VOC of 1.39 V, FF of 88%, and JSC of 24.75 mAcm-2. This research may offer crucial information and a practical plan for creating an affordable Ca3SbI3/Ca3NCl3 thin-film solar cell.

Solution-processed tungsten diselenide as an inorganic hole transport material for moisture-stable perovskite solar cells in the n-i-p architecture

Some of the obstacles to the commercialization of perovskite solar cells (PSCs) are their long-term moisture stability and material cost of the constituent layers, such as the commonly used spiro-OMeTAD hole transport layer (HTL). Replacing the spiro-OMeTAD with low-cost inorganic hole transport materials (HTMs) are important to further elevate the attractiveness of PSCs for commercialization. Perovskite-compatible, solution-exfoliated two-dimensional (2D) transition metal dichalcogenides (TMDCs) are being considered as viable candidates for inorganic HTMs. We consider one such TMDC, WSe2 which was chemically exfoliated using dichlorobenzene (DCB), a perovskite-compatible solvent, as it was integrated with triple cation perovskite absorbers within the solar cell stack. The WSe2 HTL required heat treatment processes to be maintained below 100 °C in order to preserve the integrity of the underlying perovskite; despite this lower temperature post treatment process, the structural morphology of the film revealed its dense and pinhole-free nature. Temperature-dependent transport studies conducted on the WSe2 film provided evidence of its semiconducting character and its ability to extract holes well from the underlying triple-cation Cs0.05FA0.79MA0.16PbI2.45Br0.55 absorber. The inorganic HTL offered better environmental stability in moisture-rich environments of up to 60 % relative humidity, in comparison to spiro-OMeTAD HTL-based devices which degraded faster as a result of pinholes.

Incorporation of a second CsPbl3−yIy perovskite absorber layer (y = 1, 2, or 3) into CsPbl3-based perovskite solar cells, to improve their thermal stability and performance

Incorporation of a second CsPbl3−yIy perovskite absorber layer (y = 1, 2, or 3) into CsPbl3-based perovskite solar cells, to improve their thermal stability and performance

Suppressing Interface Defects in Perovskite Solar Cells via Introducing a Plant-Derived Ergothioneine Self-Assembled Monolayer

Perovskite solar cells are among the most promising renewable energy devices, and enhancing their stability is crucial for commercialization. This research presents the use of L-Ergothioneine (L-EGT) as a passivation material in perovskite solar cells, strategically placed between the electron transport layer and the perovskite absorber layer to mitigate defect states at the heterojunction interface. Surface analysis reveals that introducing L-EGT passivation material significantly improves the quality of the perovskite film. X-ray diffraction analysis indicates that L-EGT slows down perovskite film degradation and successfully suppresses secondary phase formation. X-ray photoelectron spectroscopic analysis shows that oxygen vacancies in the lattice decrease from 29.21% to 15.81%, while Ti4+ content increases from 70.75% to 79.15%, suggesting that L-EGT effectively passivates trap states at the interface between perovskite and TiO2 electron transport layer. The reduction of defects at the interface inhibits charge accumulation and lowers the device’s internal series resistance, leading to improved overall performance. The study finds that the introduction of L-EGT significantly improves the fill factor and efficiency, with the power conversion efficiency (PCE) rising from 16.88% to 17.84%. After 720 h of aging, the PCE retains approximately 91%. The results demonstrate the significant impact of the amino acid L-EGT passivation material in suppressing interfacial defects and greatly improving the long-term stability of perovskite devices.

Substitutional Chemistry of MAPbI3: Gaining Control over Material Photostability and Photovoltaic Performance via Pb2+ Replacement

AbstractThe strategy of partial Pb2+ substitution is applied, in prototypical MAPbI3 perovskite, with a large array of metal cations in order to comprehensively explore their possible incorporation in the perovskite lattice at Pb2+ sites and thus obtain improved photostability of the absorber. An analysis of lattice parameters and optoelectronic properties of MAPb1‐xMxI∼3 compositions allowed authors to deduce which metal cations are partially incorporated in the perovskite structure and which are expelled in the form of secondary phases. Curious effects of metal incorporation are observed, such as a decrease in the tetragonal distortion ratio and a change in the band gap. This work reveals that the doping of 11 metal cations significantly improves the photostability of the MAPbI3 films. Multiple MAPb1‐xMxI∼3 formulations deliver superior power conversion efficiencies (PCEs) in solar cells. The DFT calculations further demonstrate a complex relationship between the synthetic conditions and doping patterns. The performed study is thus a stepping stone in the development of more stable perovskite absorbers with superior photovoltaic properties.

FAPbI3-nanoparticles with ligands act synergistically in absorbent layers for high-performance and stable FAPbI3 based perovskite solar cells

The performance of perovskite solar cells (PSCs) depends on the quality of the perovskite absorber layer. In this study, oleic acid (OA) and oleylamine (OAm) ligand-capped formamidinium lead iodide (FAPbI3) nanoparticles (NPs) were incorporated into the formamidinium iodide (FAI) solution, which is one of the precursors for the sequential deposition of the FAPbI3 layer. The synergistic effect of the FAPbI3-NPs and the capped ligand substantially improves the crystallinity, uniformity, and morphology of the bulk FAPbI3 perovskite films. The enhancements lead to a reduction in charge recombination and a boost in charge transfer efficiency, enabling the optimized PSCs to achieve a remarkable peak power conversion efficiency (PCE) of 25.68 %. Moreover, these PSCs show good stability, with unencapsulated devices maintaining 93 % of the peak performance under ambient air (RH 50 %) for 1000 hours.

Polymeric Charge-Transporting Materials for Inverted Perovskite Solar Cells.

Inverted perovskite solar cells (PSCs) hold exceptional promise as next-generation photovoltaic technology, where both perovskite absorbers and charge-transporting materials (CTMs) play critical roles in cell performance. In recent years, polymeric CTMs have played an important role in developing efficient, stable, and large-area inverted PSCs due to their unique properties of high conductivity, tunable structures, and mechanical flexibility. This review provides a comprehensive overview of polymeric CTMs used in inverted PSCs, encompassing polymeric hole transport materials (HTMs) and electron transport materials (ETMs). the relationship between their molecular structures, modification strategies are systematically summarized and analyzed for adjusting energy levels, and improving charge extraction, enabling a deep understanding of these widely used materials. The review also explores effective strategies for designing even more efficient polymeric CTMs. Finally, an outlook is proposed on the exciting research of novel polymeric CTMs, paving the way for their commercialized applications in PSCs.

Exceeding 23% Efficiency for 3D/3D Bilayer Perovskite Heterojunction MAPbI3/FAPbI3‐Based Hybrid Perovskite Solar Cells with Enhanced Stability

AbstractOrganic–inorganic hybrid perovskite solar cells (HPSCs) are gaining attention as a promising technology for next‐generation photovoltaic devices owing to their impressive power conversion efficiency (PCE) and cost‐effective fabrication methods. Although, solution‐processed passivation using 2D perovskites can improve the interface recombination, this approach hampers its effective charge transportation. In this study, the study investigates the properties and performance of the bilayer 3D/3D methylammonium lead iodide (MAPbI3)/formamidinium lead iodide (FAPbI3)‐based perovskite heterojunction (BPHJ) to address these concerns. The bilayer structure consists of two distinct perovskite absorbers having independent structure that are sandwiched between two charge transporting layer (CTLs) to make functional device. First, the fabrication process is optimized to achieve high‐quality MAPbI3 perovskite films with controlled morphology and crystallinity followed by the formation of BPHJ using FAPbI3 deposition by thermal evaporation technique. The BPHJ‐160 nm‐based PSCs with optimized parameters exhibit an enhanced PCE of 23.08% compared to single‐layer reference (20.15%) device. The improved performance can be attributed to the effective charge extraction at the heterojunction interface and reduced charge recombination losses due to favorable energy levels. Furthermore, the long‐term stability of the BPHJ‐based perovskite device is assessed under continuous illumination along with its ambient and thermal stability across different environmental conditions.

Enhancement of NIR-II Emission of Er3+ by Doping Fe3+ in Double Perovskites: Multimode Luminescence for Versatile Optoelectronic Applications.

Erbium ions are commonly used to extend the photoelectric properties of metal halide perovskites from visible to near-infrared range. However, achieving high-efficiency multimode luminescence in a single system is difficult due to the weak absorption associated with forbidden 4f-4f transitions. In this study, a unique strategy is proposed to adjust multimode luminescence and enhance the second near-infrared region (NIR-II) emission in Cs2NaBiCl6 by incorporating Fe3+ ions. The as-prepared material demonstrates reversible thermochromism, driven by strong electron-phonon coupling effect, and exhibits tunable luminescence that can be adjusted by altering excitation energy and temperature. Notably, benefitting from the charge transfer transition of Fe3+-Cl- along with the influence of Fe3+ doping on the geometrical and electronic structures, the blue-excitable (450 nm) NIR-II emission around 1541 nm from Er3+ is realized for the first time, achieving an intensity 16.7 times higher and a maximum photoluminescence quantum yield (PLQY) of 22.5 %. This enhancement enables innovative applications such as two-dimensional information encryption by the multi-channel cooperative responses and improved NIR imaging. The study highlights the potential of Fe3+ doping in optimizing absorption and multimode luminescence in perovskites, opening avenues for advanced applications in blue-excitable NIR light emitting diodes (LEDs), thermometer, anti-counterfeiting, and NIR imaging.

Achieving 34 % efficiency with a dual-absorber solar cell design using CaRbCl3 and Ca3NCl3 perovskites

This study’s DFT calculations show that the direct bandgaps of perovskite CaRbCl3 and Ca3NCl3 are 1.386 eV and 1.430 eV, respectively, confirming their semiconducting nature. The study also provides density of states and dielectric constant data for these materials. In photovoltaic (PV) technology, perovskites are highly valued as solar absorber materials for their exceptional optical properties, low cost, high efficiency, and lightweight design. This study presents a structure (Al/FTO/CdS/dual absorber (CaRbCl3/Ca3NCl3)/V2O5/Au) incorporating a CdS electron transport layer (ETL) and a V2O5 hole transport layer (HTL) with a double perovskite absorber layer (DPAL) of CaRbCl3 and Ca3NCl3 using SCAPS-1D. The results show that the DPAL-based perovskite solar cell (PSC) outperforms single-layer PSCs, with significant efficiency gains when HTL is included. The study thoroughly examines the effects of layer thickness, doping levels, and defect densities on key electrical parameters such as VOC, JSC, FF, and PCE. It also explores J-V and QE characteristics and the impact of temperature. The ideal absorber thickness for achieving the highest PCE is 500 nm for CaRbCl3 and 600 nm for Ca3NCl3, combined with a doping density of 1 × 1017 cm−3, a defect density of 1 × 1011 cm−3 and interface defect density of 1 × 1010 cm−2. While single-absorber solar cells achieve maximum efficiencies of 24.40 % (CaRbCl3) and 24.02 % (Ca3NCl3), the DPAL setup reaches an optimized efficiency of 27.66 %, further increasing to 34.39 % with a VOC of 1.295 V, FF of 83.95 %, and JSC of 31.63 mA/cm2 when using V2O5 HTL. This research provides valuable insights and a practical strategy for developing cost-effective CaRbCl3/Ca3NCl3 thin-film solar cells.

Metal–Organic Frameworks and Derivative Materials in Perovskite Solar Cells: Recent Advances, Emerging Trends, and Perspectives

The power conversion efficiency (PCE) of perovskite solar cells (PSCs) has reached an impressive value of 26.1%. While several initiatives such as structural modification and fabrication techniques helped steadily increase the PCE and stability of PSCs in recent years, the incorporation of metal–organic frameworks (MOFs) in PSCs stands out among other innovations and has emerged as a promising path forward to make this technology the front‐runner for realizing next‐generation low‐cost photovoltaic technologies. Owing to their unique physiochemical properties and extraordinary advantages such as large specific surface area and tunable pore structures, incorporating them as/in different functional layers of PSCs endows the devices with extraordinary optoelectronic properties. This article reviews the latest research practices adapted in integrating MOFs and derivative materials into the constituent blocks of PSCs such as photoactive perovskite absorber, electron‐transport layer, hole‐transport layer, and interfacial layer. Notably, a special emphasis is placed on the aspect of stability improvement in PSCs by incorporating MOFs and derivative materials. Also, the potential of MOFs as lead absorbents in PSCs is highlighted. Finally, an outlook on the critical challenges faced and future perspectives for employing MOFs in PSCs in light of the commercialization of PSCs is provided.

A review of the progress of metal-organic frameworks in perovskite solar cells

Organic-inorganic hybrid perovskite solar cells (PSCs) have emerged as substantial challenges for future generations of photovoltaic apparatus, largely attributed to their power conversion efficiency (PCE) drastically elevated from below 10% to a staggering 25.7% over the past decade. Owing to characteristics distinct to them like substantial specific surface areas, copious binding locations, adjustable nanostructures, and mutual reinforcement, metal-organic frameworks (MOFs) are commonly utilized as either supplementary components or operational layers for augmenting both the efficiency and durability of PSCs. This paper primarily underlines the recent advancements in implementing MOFs across various operational strata of a PSC. The focal points of this study encompass an examination of the photovoltaic yields, the repercussions, and the advantages of fusing MOF materials into constituents like perovskite absorbers, electron transport, and hole transport layers, in addition to interface layers. The study also extends to an exploration of how MOFs effectively inhibit leakages of Pb2+ within halide perovskites and their associated apparatus. This paper concludes by discerning and shedding light on potential research prospects for the deployment of MOFs in PSCs.

Computational Screening Two-Dimensional Conjugated Microporous Polymer Applied in Perovskite Solar Cells.

A two-dimensional (2D) conjugated microporous polymer with a structure of 2D nanosheets has been synthesized. Theoretical calculations and experimental results reveal that the Fermi level of this 2D polymer aligns well with perovskite absorber, and its conduction band is high enough to block electron transport into the anode. This 2D polymer is used to modify the hole transport layer, significantly improving its photoelectric properties, including enhanced hole mobility, matched energy level, and reduced recombination. Furthermore, the 2D polymer exhibits a mesoporous structure, allowing perovskite to fill into its loose framework, increasing the hole export area and providing a large hole transport flux. As a result, the efficiency of inverted perovskite solar cells enhances to 24.64 % from 21.17 % of control device without 2D conjugated microporous polymer. Given that this material can be synthesized on a large scale, this work has significant implications for the future development of 2D polymers in perovskite solar cells, potentially accelerating industrialization.

Recent Progress on Cross-Linkable Fullerene-Based Electron Transport Materials for Perovskite Solar Cells.

Fullerene-based derivatives are frequently used as electron transport materials (ETMs) and interface buffers for perovskite solar cells (PSCs) due to their excellent properties, including high electron affinity and mobility, low recombination energy, tunable energy levels, and solution processability. However, significant challenges arise because fullerene derivatives tend to aggregate and dimerize, which reduces exciton dissociation and charge transport capacity. Additionally, their chemical compatibility with perovskite absorbers facilitates halide diffusion and degradation of PSCs. This overlap causes delamination and dissolution during device fabrication, hindering the performance enhancement of fullerene-based PSCs. To address these issues, researchers have developed cross-linkable fullerene materials. These materials have been shown to not only significantly improve the power conversion efficiency (PCE) of PSCs but also effectively enhance the device stability. In this review, we summarized recent research progress on cross-linkable fullerene derivatives as ETMs for PSCs. We systematically analyze the impact of these cross-linked ETMs on device performance and long-term stability, focusing on their molecular structures and working mechanisms. Finally, we discuss the future challenges that need to be overcome to advance the application of cross-linkable fullerene materials in PSCs.

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).

Tuning Perovskite Crystal Growth Dynamics Using Additives on Textured Silicon Substrates

Double‐sided textured silicon solar cells with micrometer‐sized pyramid structure are used as bottom cells in monolithic tandem structures to decrease reflection losses. As top cell material, frequently perovskites are used. In this work, various additives are investigated to enhance the perovskite absorber quality, as a top cell fabricated using the hybrid route. In the context of the hybrid route, it is found that urea or methylammonium chloride (MACl) can effectively increase the grain size and improve the absorber quality, while formamidinium chloride (FACl) cannot. With urea, the crystallization can be tuned without leaving any voids in the film (unlike MACl). However, when annealed at a high annealing temperature, the excessive crystal growth with urea causes non‐conformal coating and high defect density. By adjusting the annealing conditions and additive concentration, the crystal growth of the perovskite top cell on the micrometer‐sized silicon pyramids can be fine‐tuned, ensuring that the perovskite layer conformally coated the pyramids. The use of additives not only improves crystallization but also enhances the conversion of the inorganics, particularly at the hole transport layer (HTL) interface. Moreover, this work contributes to a better understanding of perovskite crystallization dynamics and how to control it, especially on textured substrates.

Overcoming the Open-Circuit Voltage Losses in Narrow Bandgap Perovskites for All-Perovskite Tandem Solar Cells.

Narrow-bandgap (NBG) perovskite solar cells based on tin-lead mixed perovskite absorbers suffer from significant open-circuit voltage (V OC) losses due primarily to a high defect density and charge carrier recombination at the device interfaces. In this study, the V OC losses in NBG perovskite single junction cells (E g = 1.21 eV) are addressed. The optimized NBG subcell is then used to fabricate highly efficient all-perovskite tandem solar cells (TSCs). The improvement in the V OC is achieved via the addition of a thin poly(triarylamine) interlayer between the poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS)-based hole transport layer (HTL) and the NBG perovskite. The optimal bilayer HTL results in a champion power conversion efficiency (PCE) of 20.3%, compared to 17.8% of the PEDOT:PSS-based control device. The V OC improvement of the single-junction NBG cell is also successfully transferred to all-perovskite TSC, resulting in a high V OC of 2.00 V and a PCE of 25.1%.

Bifunctional Nitrogen-Rich Heterocyclic Compounds: Synthesis, Photoluminescence and Energetic Properties.

Nitrogen-rich heterocyclic frameworks have attracted enormous interest in organic chemistry and materials science. However, their potential for developing photoluminescent materials remains underexplored due to their relatively low molecular stabilities. In this work, two tricyclic fused nitrogen-rich fluorescent heterocycles were synthesized and characterized. The photophysical properties of the synthesized 4 and 5 were investigated through theoretical and experimental studies. In addition, their physicochemical and energetic properties and the performance as an additive to the perovskite absorption layer of the perovskite solar cell were also studied.