Materials For Perovskite Solar Cells Research Articles

“Exploration of Photovoltaic Behavior of Bithiophene-functionalized Dispiro-oxepine based Hole-transporting Materials for Efficient Perovskite Solar Cells”

Abstract Perovskite solar cells (PSCs) have got great attention from researchers due to their superior photovoltaic properties, high efficiency, and low cost. In this study, bithiophene dispiro-oxepine based five hole-transporting materials (DDOF1, DDOF2, DDOF3, DDOF4, and DDOF5) are designed by the substitution of end-capped acceptors via thiophene-based bridge to enhance the photovoltaic properties of PSCs. The results showed that designed HTMs have deeper HOMO levels (-4.88 eV to -5.04 eV), high solubility, and compatible stability with low band gaps (2.04 eV to 2.59 eV) than the reference molecule (EHOMO = -4.55 eV, Eg = -3.49 eV), which improved hole extraction and the open-circuit voltage in the PSCs. Moreover, the binding energy (0.41 eV to 0.46 eV) and TDM analysis indicated that DDOF1-DDOF5 HTMs have high charge mobility compared to the reference molecule DDOF (0.61 eV). The DDOF1-DDOF5 HTMs indicated anticipated high power conversion efficiency and open-circuit voltage than the reference molecule. Overall, our findings proved that designed molecules are efficient HTMs for the manufacture of high-efficiency PSCs in the solar industry.

Fast Exploring Literature by Language Machine Learning for Perovskite Solar Cell Materials Design

Making computers automatically extract latent scientific knowledge from literature is highly desired for future materials and chemical research in the artificial intelligence era. Herein, the natural language processing (NLP)‐based machine learning technique to build language models and automatically extract hidden information regarding perovskite solar cell (PSC) materials from 29 060 publications is employed. The concept that there are light‐absorbing materials, electron‐transporting materials, and hole‐transporting materials in PSCs is successfully learned by the NLP‐based machine learning model without a time‐consuming human expert training process. The NLP model highlights a hole‐transporting material that receives insufficient attention in the literature, which is then elaborated via density functional theory calculations to provide an atomistic view of the perovskite/hole‐transporting layer heterostructures and their optoelectronic properties. Finally, the above results are confirmed by device experiments. The present study demonstrates the viability of NLP as a universal machine learning tool to extract useful information from existing publications.

Molecular engineering of benzothiadiazole core based non-fullerene acceptors to tune the optoelectronic properties of perovskite solar cells

Non-fullerene acceptors exhibit durable absorption capacity, and exceptional power conversion efficiency that make them appealing photovoltaic material for use as hole transport materials in perovskite solar cells (PSCs). To interpret the benzothiadiazole as the central-core unit, five novel acceptors (U1-U5) have been successfully fabricated by end-capped engineering. Their electrical and optical performance have been investigated theoretically. Utilizing density functional theory (DFT) and time-dependent DFT computations, we have examined the photo-physical and optoelectronic characteristics. U4 exhibits 3.80 eV optical band gap with an absorption (λmax) of 670.58 nm. Lowest excitation energy (1.85 eV), greater LHE (0.98) and improved PCE (18.31 eV) validate the U4 designed molecule as a brilliant photovoltaic material for PSCs. Outstanding charge transfer at the donor–acceptor junction has also been revealed by thorough analysis of U4/PTB7-Th. Therefore, substitution of alternate functional groups in terminal moieties is efficient for effective PSCs that can be used as photon harvesting materials.

3D Conjugated Hole Transporting Materials for Efficient and Stable Perovskite Solar Cells and Modules.

The orthogonal structure of the widely used hole transporting material (HTM) Spiro-OMeTAD imparts isotropic conductivity and excellent film-forming capability. However, inherently weak intra- and inter-molecular π-π interactions result in low intrinsic hole mobility. Herein, a novel arylamine derivative, termed FTPE-ST, with a twist conjugated dibenzo[g,p]chrysene core and coplanar 3,4-ethylenedioxythiophene (EDOT) as extended donor units, was designed to enhance intra- and inter-molecular π-π interactions, without compromising on solubility. The 3D configuration provides the material multi-direction charge transport as well as excellent solubility even in 2-methylanisole (2-MA), and its large conjugated delocalization backbone endows the HTM with a high hole mobility (7.2 × 10-4 cm2V-1s-1). Moreover, the sulfur donors in the EDOT units coordinate to lead ions on the perovskite surface, leading to stronger interfacial interactions and the suppression of defects at the perovskite/HTM interface. As a result, perovskite solar cells (PSCs) employing FTPE-ST as the HTM achieve a champion power conversion efficiency (PCE) of 25.21% with excellent long-time stability, which is one of the highest PCEs for non-spiro HTMs in n-i-p PSCs. In addition, the excellent film-forming capacity of the HTM enables the fabrication of FTPE-ST-based large-scale PSCs (1.0 cm2) and modules (29.0 cm2), which achieve PCEs of 24.21% (certificated 24.17%) and 21.27%, respectively. This article is protected by copyright. All rights reserved.

Utilizing a Carbazole‐Incorporated Regioisomeric Synthesis Strategy to Design Hole Transporting Materials for Perovskite Solar Cells

Two new p‐type molecules, namely TAT‐TY3 and TAT‐TY4, featuring triazatruxene endcaps and carbazole π‐bridges, were synthesized. The photophysical and electrochemical properties of synthesized materials were comparatively investigated based on their 2,7‐ and 3,6‐carbazole conjugation pathways. Optical characterizations revealed the impact of non‐bonding electron delocalization of triazatruxene through carbazole moieties, resulting in a significant increase in absorption intensity corresponding to n‐π* energy transitions and a red shift of triazatruxene moieties. Consequently, the optical band gaps of TAT‐TY3 and TAT‐TY4 were measured at 3.0 and 3.2 eV, respectively. Moreover, the molecules' first oxidation potentials exhibited a drastic difference due to the electrochemical behavior of 2,7‐ and 3,6‐carbazole moieties. The highest occupied molecular orbital (HOMO) level for TAT‐TY3 was measured to be ‐5.02 eV, while for TAT‐TY4, it was measured as ‐4.67 eV. Hole‐extraction properties were explored using steady‐state and time‐resolved photoluminescence spectroscopy, revealing enhanced charge transfer between the TAT‐TY3/Perovskite interface due to the better alignment of HOMO energy levels. The photovoltaic performances of the hole‐transporting materials (HTMs) were successfully characterized in triple‐cation perovskite solar cells and efficiencies of up to 17.9%, 16.2%, and 9.8% were achieved for Spiro‐OMeTAD, TAT‐TY3, and TAT‐TY4, respectively.

Recent Advances in Self-Assembled Molecular Application in Solar Cells.

Perovskite solar cells (PSCs) have attracted much attention due to their low cost, high efficiency, and solution processability. With the development of various materials in perovskite solar cells, self-assembled monolayers (SAMs) have rapidly become an important factor in improving power conversion efficiency (PCE) due to their unique physical and chemical properties and better energy level matching. In this topical review, we introduced important categories of self-assembled molecules, energy level modulation strategies, and various characteristics of self-assembled molecules. In addition, we focused on reviewing the application of self-assembled molecules in solar cells, and explained the changes that self-assembled molecules bring to PSCs by introducing the mechanism and effect of self-assembled molecules. Finally, we also elaborated on the challenges currently faced by self-assembled molecules and provided prospects for their applications in other optoelectronic devices.

A facile approach for design of novel semiconducting thiazolo[5,4-d]thiazole-based conjugated polymers in ambient conditions

The design of conjugated polymers with advanced properties is a significant task for the development of organic electronics. At the same time, it is important to pay attention to the methods of their synthesis, excluding toxic and expensive reagents, following the trends in sustainability. In this study, six thiazolothiazole-based conjugated polymers with thiophene, fluorene, phenylene, and benzodithiophene moieties were synthesized and thoroughly characterized. All materials were obtained through a non-catalyzed condensation reaction of carbonyl derivatives with rubeanic acid under ambient conditions. It is shown that the optoelectronic and electrophysical properties of polymers are suitable for their application in organic or hybrid electronic devices. The certain polymers are found to be promising hole-transport interlayer materials in perovskite solar cells, thus featuring the great potential of proposed methods of development of organic semiconductors.

High-performance quasi-2D perovskite solar cells enabled by using π-conjugated spacer

The excellent photoelectric properties and low fabrication cost of perovskite solar cells have attracted extensive research attention. Despite this, long-term stability issues associated with perovskite solar cells continue to pose a significant barrier to commercialization. A new generation of two-dimensional (2D) and quasi-2D perovskites and newly introduced members of the 2D material family, have attracted growing attention due to their excellent stability and physical properties in contrast to their three-dimensional (3D) counterparts. Herein, we have presented the feasibility of using 4,4[Formula: see text]-dipyridyl as an additive material for quasi-2D perovskite solar cells. As a result of the addition of 4,4[Formula: see text]-dipyridyl, the solar cell device achieves a power conversion efficiency of 17.92% and a fill factor of 76.5%. Additionally, this strategy can be expanded to quasi-2D perovskite solar cells with an open-circuit voltage of 1.05[Formula: see text]V.

Fluorination effects on bithiophene bridged hole transporting materials for perovskite solar cells

ABSTRACT The use of hole transporting material (HTM) remains indispensable for efficient charge extraction in perovskite solar cells. In this work, a series of small-molecule HTMs are designed by introducing fluorine atoms into the central part of 2,2′-bithiophene core. The effect of fluorination on the photophysical, electrochemical, and hole transport properties is systematically explored using Quantum chemistry calculation. The Calculated results reveal that all the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) of the studied molecules are well matched with the energy band structure of perovskite. Three fluorine substituted hole-transporting materials possess lower reorganisation energy than the reference molecule BT-MTP. The higher mobility and matched energy levels of predicted HTMs are beneficial for improving the performance of PSCs. All the designed HTMs display higher hole mobility than those of the BT-MTP. Especially, molecule DFBT-p-MTP exhibits better optical properties and stability, indicating that fluorination is an effective strategy to improve the performance of the device in real application. This work provides an avenue for designing low-cost small molecule HTMs for high-performance perovskite solar cells.

Studies on the performance of FASnI3:Zn2+-based lead-free perovskite solar cells: A numerical simulation

The search of stable, lead-free absorber material for perovskite solar cells (PSC) resulted in many alternatives, particularly, zinc (Zn) doped formamidinium tin iodide (FASnI3). This work facilitates in investigating the behavior of four different Zn doping ratios 0%, 2%, 5%, and 10% (say Zn-0, Zn-2, Zn-5, and Zn-10) on the performance of FTO/PCBM/FASnI3:Zn2+/MoOx/Au solar cell structure. A precise evaluation on the impact of the four various Zn doping ratios in the mentioned solar structure in terms of thickness of perovskite absorber layer, hole transport layer, and electron transport layer were executed. The investigation through numerical study further deals with the role of interfacial defect density and capture cross-section of charge carriers on the performance of suggested PSCs with varying Zn doping ratios. It is evident from the optimization results that PSC having absorber layer thickness of 400nm yields better power conversion efficiency (PCE) of 11.49% for Zn-5. The PCE is further improved to 13.98% for capture cross section of 2 ×10-15 cm2. The entire work witnessed distinguishable superior behavior from FASnI3-based PSC doped with Zn ratio: Zn-5 in comparison to the PSCs doped with other Zn ratios. Furthermore, impact of the series and shunt resistances on performance parameters are also examined.

Molybdenum doped tin oxide as electron transport material in air-processable perovskite solar cells

Molybdenum doped tin oxide as electron transport material in air-processable perovskite solar cells

Machine Learning for Screening Small Molecules as Passivation Materials for Enhanced Perovskite Solar Cells

AbstractUtilization of small molecules as passivation materials for perovskite solar cells (PSCs) has gained significant attention recently, with hundreds of small molecules demonstrating passivation effects. In this study, a high‐accuracy machine learning model is established to identify the dominant molecular traits influencing passivation and efficiently screen excellent passivation materials among small molecules. To address the challenge of limited available dataset, a novel evaluation method called random‐extracted and recoverable cross‐validation (RE‐RCV) is proposed, which ensures more precise model evaluation with reduced error. Among 31 examined features, dipole moment is identified, hydrogen bond acceptor count, and HOMO‐LUMO gap as significant traits affecting passivation, offering valuable guidance for the selection of passivation molecules. The predictions are experimentally validate with three representative molecules: 4‐aminobenzenesulfonamide, 4‐Chloro‐2‐hydroxy‐5‐sulfamoylbenzoic acid, and Phenolsulfonphthalein, which exhibit capability to increase absolute efficiency values by over 2%, with a champion efficiency of 25.41%. This highlights its potential to expedite advancements in PSCs.

Thiophene-based compounds containing naphthalene groups as Hole Transport Materials for efficient Perovskite Solar Cells or light absorbers in Organic Solar Cells

This study mainly focuses on modelling and analysis of the reference molecule (M104) as well as four engineered molecules (MMS1-MMS4) as Hole Transport Materials or as light absorbers in Organic Solar Cells. These new molecules are based on thiophene derivatives as acceptor groups, naphthalene as π-bridged groups, and OMeTPA as donor groups. Extensive research was carried out at the molecular level for the studied molecules using DFT and TD-DFT computer simulations to explore their photovoltaic characteristics. All the compounds under investigation were preferred candidate for HTMs in perovskite solar cells because of their superior HOMO delocalization, lower hole reorganization energies, lower chemical reactivity, higher radiative lifetime, higher light-harvesting efficiency, higher dipole moment and spontaneous solvation process inside dichloromethane. The examined molecules' bonded electron-hole pairs can readily split into positive and negative charges to escape coulomb attraction. This increases the short-circuit current density and facilitates hole transport. MMS4, with its larger maximum absorbance (538.76 nm in dichloromethane), suitable structural features and lower bandgap (2.82 eV), was the most optimal chemical with remarkable photovoltaic capabilities. In conclusion, this work makes a strong case for the synthesis of these high-performing materials by researchers for use in subsequent investigations.

Rational designing of phenothiazine dioxide based hole transporting materials for efficient perovskite solar cells

In this study, we design five novel non-fullerene end capped acceptor based efficient hole transporting materials (HTMs) from phenothiazine dioxide-based core. MPW1PW91 functional with a 6-31G basis set was employed for all DFT calculations and simulation analysis. By substituting acceptor groups in PDO2, numbers of parameters like band gaps, the frontier molecular orbitals (FMOs), higher absorption parameters, and electronic properties like ionization potential, electron affinity, binding energy, and light harvesting efficiency (LHE) were well tuned. In addition, significant variations in other geometrical parameters such as dipole moment, and reorganizational energy parameters were also noticed for the derived molecules compared to the reference molecule (R). Device performance was analyzed by performing calculations of open circuit voltage (VOC) and fill factor (FF). Consequently, all the designed derivatives demonstrated an improved VOC of 0.84 V for an optimized designed structure. In comparison, it was limited to a VOC of 0.57 V for the reference (R) PDO2, displaying an increment in efficiency which is essential to use these molecules as highly efficient HTMs for perovskite solar cell devices in the future.

Highly ordered crystallization of α-FAPbI3 films via homogeneous seeds for efficient perovskite solar cells

Formamidine lead triiodide (FAPbI3) perovskites have become the most promising photovoltaic materials for perovskite solar cells with record power conversion efficiency (PCE). However, random nucleation, phase transition, and lattice defects are still the key challenges limiting the quality of FAPbI3 films. Previous studies show that the introduction or adding of seeds in the precursor is effective to promote the nucleation and crystallization of perovskite films. Nevertheless, the seed-assisted approach focuses on heterogeneous seeds or hetero-composites, which inevitably induce a lattice-mismatch, the generation of strain or defects, and the phase segregation in the perovskite films. Herein, we first demonstrate that high-quality perovskite films are controllably prepared using α- and δ-phases mixed FAPbI3 microcrystal as the homogeneous seeds with the one-step antisolvent method. The partially dissolved seeds with suitable sizes improve the crystallinity of the perovskite film with preferable orientation, improved carrier lifetime, and increased carrier mobility. More importantly, the α-phase-containing seeds promote the formation of α-phase FAPbI3 films, leading to the reduction of residual lattice strain and the suppression of I− ion migration. Besides, the adding of dimethyl 2,6-pyridine dicarboxylate (DPD) into the precursor further suppresses the generation of defects, contributing to the PCE of devices prepared in air ambient being significantly improved to 23.75%, among the highest PCEs for fully air-processed FAPbI3 solar cells. The unpackaged target devices possess a high stability, maintaining 80% of the initial PCE under simulated solar illumination exceeding 800 h.

Investigating the Electrical and Optical Properties of Nickle and Strontium Co-Doped CsPbBr3 Nanocrystals: Potential Absorber Material for Perovskite Solar Cells

Investigating the Electrical and Optical Properties of Nickle and Strontium Co-Doped CsPbBr3 Nanocrystals: Potential Absorber Material for Perovskite Solar Cells

First-principles study on the stability and degradation of the lead-free double perovskite materials Cs2B'BiCl6 (B' = Li, Na, K) under natural environment

The stability of perovskite solar cell materials in the natural environment is crucial to their commercial application. Understanding the detailed interaction mechanism between the air or water molecules (H2O) and the perovskite materials is a key way to explore their stabilities. In this study, we evaluate the geometric stabilities and thermodynamic stabilities of the lead-free Cs2B'BiCl6 (B' = Li, Na, K) double perovskite materials, and further explore the effect of air and H2O molecules on the stability and degradation of the Cs2B'BiCl6 double perovskite materials. The calculated results indicate that the pristine Cs2B'BiCl6 materials possess good geometric stabilities and thermodynamic stabilities. Under natural environment, the N2, O2, and CO2 gas molecules hardly penetrate into Cs2LiBiCl6 and Cs2NaBiCl6 because of positive absorption energies, while N2 and O2 can easily penetrate into Cs2KBiCl6 due to negative absorption energies. In contrast, the H2O molecules can easily penetrate into all Cs2B'BiCl6 double perovskite materials with negative absorption energies. Furthermore, the penetration of H2O molecules causes structural deformations of the double perovskites and the resultant rotation or rupture of some octahedra. Further simulations of H2O molecules adsorption on the surface of the double perovskites reveal that the adsorption energies of H2O molecules at all adsorption sites are negative, indicating that the Cs2B'BiCl6 double perovskite materials are prone to absorb H2O molecules in a humid environment. Therefore, the H2O molecules are the main factor affecting the stability and degradation of all Cs2B'BiCl6 double perovskite materials. Additionally, Cs2KBiCl6 shows much worse stability, which is responsible for the scarcely experimental reports on its synthesis and characterization.

Improvement in Dibenzofuran-Based Hole Transport Materials for Flexible Perovskite Solar Cells.

The π-conjugated system and the steric configuration of hole transport materials (HTMs) could greatly affect their various properties and the corresponding perovskite solar cells' efficiencies. Here, a molecular engineering strategy of incorporating different amounts of p-methoxyaniline-substituted dibenzofurans as π bridge into HTMs was proposed to develop oligomer HTMs, named mDBF, bDBF, and tDBF. Upon extending the π-conjugation of HTMs, their HOMO energy levels were slightly deepened, significantly increasing the thermal stability and hole mobility. The incorporation of p-methoxyaniline bridges built one or two additional triphenylamine propeller structures, resulting in a denser film. Here, the tDBF-based n-i-p flexible perovskite solar cells createdchampion efficiency, giving a power conversion efficiency of 19.46%. And the simple synthesis and purification process of tDBF contributed to its low manufacturing cost in the laboratory. This work provided a reference for the development of low-cost and efficient HTMs.

Formamidinium Lead Iodide-Based Inverted Perovskite Solar Cells with Efficiency over 25 % Enabled by An Amphiphilic Molecular Hole-Transporter.

Formamidinium lead iodide (FAPbI3) represents an optimal absorber material in perovskite solar cells (PSCs), while the application of FAPbI3 in inverted-structured PSCs has yet to be successful, mainly owing to its inferior film-forming on hydrophobic or defective hole-transporting substrates. Herein, we report a substantial improvement of FAPbI3-based inverted PSCs, which is realized by a multifunctional amphiphilic molecular hole-transporter, (2-(4-(10H-phenothiazin-10-yl)phenyl)-1-cyanovinyl)phosphonic acid (PTZ-CPA). The phenothiazine (PTZ) based PTZ-CPA, carrying a cyanovinyl phosphonic acid (CPA) group, forms a superwetting hole-selective underlayer that enables facile deposition of high-quality FAPbI3 thin films. Compared to a previously established carbazole-based hole-selective material (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz), the crystallinity of FAPbI3 is enhanced and the electronic defects are passivated by the PTZ-CPA more effectively, resulting in remarkable increases in photoluminescence quantum yield (four-fold) and Shockley-Read-Hall lifetime (eight-fold). Moreover, the PTZ-CPA shows a larger molecular dipole moment and improved energy level alignment with FAPbI3, benefiting the interfacial hole-collection. Consequently, FAPbI3-based inverted PSCs achieve an unprecedented efficiency of 25.35 % under simulated air mass 1.5 (AM1.5) sunlight. The PTZ-CPA based device shows commendable long-term stability, maintaining over 90 % of its initial efficiency after continuous operation at 40 °C for 2000 hours.

Formamidinium Lead Iodide‐Based Inverted Perovskite Solar Cells with Efficiency over 25 % Enabled by An Amphiphilic Molecular Hole‐Transporter

AbstractFormamidinium lead iodide (FAPbI3) represents an optimal absorber material in perovskite solar cells (PSCs), while the application of FAPbI3 in inverted‐structured PSCs has yet to be successful, mainly owing to its inferior film‐forming on hydrophobic or defective hole‐transporting substrates. Herein, we report a substantial improvement of FAPbI3‐based inverted PSCs, which is realized by a multifunctional amphiphilic molecular hole‐transporter, (2‐(4‐(10H‐phenothiazin‐10‐yl)phenyl)‐1‐cyanovinyl)phosphonic acid (PTZ−CPA). The phenothiazine (PTZ) based PTZ−CPA, carrying a cyanovinyl phosphonic acid (CPA) group, forms a superwetting hole‐selective underlayer that enables facile deposition of high‐quality FAPbI3 thin films. Compared to a previously established carbazole‐based hole‐selective material (2‐(3,6‐dimethoxy‐9H‐carbazol‐9‐yl)ethyl)phosphonic acid (MeO−2PACz), the crystallinity of FAPbI3 is enhanced and the electronic defects are passivated by the PTZ−CPA more effectively, resulting in remarkable increases in photoluminescence quantum yield (four‐fold) and Shockley‐Read‐Hall lifetime (eight‐fold). Moreover, the PTZ−CPA shows a larger molecular dipole moment and improved energy level alignment with FAPbI3, benefiting the interfacial hole‐collection. Consequently, FAPbI3‐based inverted PSCs achieve an unprecedented efficiency of 25.35 % under simulated air mass 1.5 (AM1.5) sunlight. The PTZ−CPA based device shows commendable long‐term stability, maintaining over 90 % of its initial efficiency after continuous operation at 40 °C for 2000 hours.