Enhancing Efficiency and Stability of Inverted Perovskite Solar Cells through Solution-Processed and Structurally Ordered Fullerene.

The electron transporting layer (ETL) used in high performance inverted perovskite solar cells (PSCs) is typically composed of C60, which requires time-consuming and costly thermal evaporation deposition, posing a significant challenge for large-scale production. To address this challenge, herein, we present a novel design of solution-processible electron transporting material (ETM) by grafting a non-fullerene acceptor fragment onto C60. The synthesized BTPC60 exhibits an exceptional solution processability and well-organized molecular stacking pattern, enabling the formation of uniform and structurally ordered film with high electron mobility. When applied as ETL in inverted PSCs, BTPC60 not only exhibits excellent interfacial contact with the perovskite layer, resulting in enhanced electron extraction and transfer efficiency, but also effectively passivates the interfacial defects to suppress non-radiative recombination. Resultant BTPC60-based inverted PSCs deliver an impressive power conversion efficiency (PCE) of 25.3% and retain almost 90% of the initial values after aging at 85°C for 1500 hours in N2. More encouragingly, the solution-processed BTPC60 ETL demonstrates remarkable film thickness tolerance, and enables a high PCE up to 24.8% with the ETL thickness of 200 nm. Our results highlight BTPC60 as a promising solution-processed fullerene-based ETM, opening an avenue for improving the scalability of efficient and stable inverted PSCs.

One-Stone-For-Three-Birds Strategy Using a Fullerene Modifier for Efficient and Stable Inverted Perovskite Solar Cells.

The electron extraction from perovskite/C60 interface plays a crucial role in influencing the photovoltaic performance of inverted perovskite solar cells (PSCs). Here, we develop a one-stone-for-three-birds strategy via employing a novel fullerene derivative bearing triple methyl acrylate groups (denoted as C60-TMA) as a multifunctional interfacial layer to optimize electron extraction at the perovskite/C60 interface. It is found that the C60-TMA not only passivates surface defects of perovskite via coordination interactions between C=O groups and Pb2+ cations but also bridge electron transfer between perovskite and C60. Moreover, it effectively induces the secondary grain growth of the perovskite film through strong bonding effect, and this phenomenon has never been observed in prior art reports on fullerene related studies. The combination of the above three upgrades enables improved perovskite film quality with increased grain size and enhanced crystallinity. With these advantages, C60-TMA treated PSC devices exhibit a much higher power conversion efficiency (PCE) of 24.89% than the control devices (23.66%). Besides, C60-TMA benefits improved thermal stability of PSC devices, retaining over 90% of its initial efficiency after aging at 85 °C for 1200 h, primarily due to the reinforced interfacial interactions and improved perovskite film quality.

Efficient and Stable Inverted Perovskite Solar Cells Enabled by a Fullerene-Based Hole Transport Molecule.

Designing an efficient modification molecule to mitigate non-radiative recombination at the NiOx/perovskite interface and improve perovskite quality represents a challenging yet crucial endeavor for achieving high-performance inverted perovskite solar cells (PSCs). Herein, we synthesized a novel fullerene-based hole transport molecule, designated as FHTM, by integrating C60 with 12 carbazole-based moieties, and applied it as a modification molecule at the NiOx/perovskite interface. The in-situ self-doping effect, triggered by electron transfer between carbazole-based moiety and C60 within the FHTM molecule, along with the extended π conjugated moiety of carbazole groups, significantly enhances FHTM's hole mobility. Coupled with optimized energy level alignment and enhanced interface interactions, the FHTM significantly enhances hole extraction and transport in corresponding devices. Additionally, the introduced FHTM efficiently promotes homogeneous nucleation of perovskite, resulting in high-quality perovskite films. These combined improvements led to the FHTM-based PSCs yielding a champion efficiency of 25.58% (Certified: 25.04%), notably surpassing that of the control device (20.91%). Furthermore, the unencapsulated device maintained 93% of its initial efficiency after 1000 hours of maximum power point tracking under continuous one-sun illumination. This study highlights the potential of functionalized fullerenes as hole transport materials, opening up new avenues for their application in the field of PSCs.

Novel Mechanism by a Bis-Pyridinium Fullerene Derivative to Induce Apoptosis by Enhancing the MEK-ERK Pathway in a Reactive Oxygen Species-Independent Manner in BCR-ABL-Positive Chronic Myeloid Leukemia-Derived K562 Cells.

In the treatment of breakpoint cluster region-Abelson (BCR-ABL)-positive chronic myeloid leukemia (CML) using BCR-ABL inhibitors, the appearance of a gatekeeper mutation (T315I) in BCR-ABL is a serious issue. Therefore, the development of novel drugs that overcome acquired resistance to BCR-ABL inhibitors by CML cells is required. We previously demonstrated that a bis-pyridinium fullerene derivative (BPF) induced apoptosis in human chronic myeloid leukemia (CML)-derived K562 cells partially through the generation of reactive oxygen species (ROS). We herein show that BPF enhanced the activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase-extracellular signal-regulated kinase (MEK-ERK) pathway in a ROS-independent manner. BPF-induced apoptosis was attenuated by trametinib, suggesting the functional involvement of the MEK-ERK pathway in apoptosis in K562 cells. In addition, the constitutive activation of the MEK-ERK pathway by the enforced expression of the BRAFV600E mutant significantly increased the sensitivity of K562 cells to BPF. These results confirmed for the first time that BPF induces apoptosis in K562 cells through dual pathways-ROS production and the activation of the MEK-ERK pathway. Furthermore, BPF induced cell death in transformed Ba/F3 cells expressing not only BCR-ABL but also T315I mutant through the activation of the MEK-ERK pathway. These results indicate that BPF is as an effective CML drug that overcomes resistance to BCR-ABL inhibitors.

Self-diffusion of water-soluble fullerene derivatives in mouse erythrocytes.

Self-diffusion of water-soluble fullerene derivative (WSFD) C60[S(CH2)3SO3Na]5H in mouse red blood cells (RBC) was characterized by 1H pulsed field gradient NMR technique. It was found that a fraction of fullerene molecules (~13% of the fullerene derivative added in aqueous RBC suspension) shows a self-diffusion coefficient of (5.5 ±â€¯0.8)·10-12 m2/s, which is matching the coefficient of the lateral diffusion of lipids in the erythrocyte membrane (DL = (5.4 ±â€¯0.8)·10-12 m2/s). This experimental finding evidences the absorption of the fullerene derivative by RBC. Fullerene derivative molecules are also absorbed by RBC ghosts and phosphatidylcholine liposomes as manifested in self-diffusion coefficients of (7.9 ±â€¯1.2)·10-12 m2/s and (7.7 ±â€¯1.2)·10-12 m2/s, which are also close to the lateral diffusion coefficients of (6.5 ±â€¯1.0)·10-12 m2/s and (8.5 ±â€¯1.3)·10-12 m2/s, respectively. The obtained results suggest that fullerene derivative molecules are, probably, fixed on the RBC surface. The average residence time of the fullerene derivative molecule on RBC was estimated as 440 ±â€¯70 ms. Thus, the pulsed field gradient NMR was shown to be a versatile technique for investigation of the interactions of the fullerene derivatives with blood cells providing essential information, which can be projected on their behavior in-vivo after intravenous administration while screening as potential drug candidates.

Synthesis, Aggregation Behavior, and Photodynamic Properties of a Water-Soluble Fulleropyrrolidine Bearing an N-PEG Pyridinium Unit.

Herein, we describe the synthesis of a water-soluble photodynamically active fullerene bearing a polyethylene glycol chain and a hydrophilic cationic group, revealing that the solubility of the above derivative in aqueous medium depends on ultrasonication time, with the particle size of aggregates being correlated with concentration.

Sulfonate-modified fullerenes mimicking tentacle structures for humidity sensors.

In this work, a straightforward method for synthesizing fullerene derivatives with tentacle structures has been explored for monitoring environmental humidity, which involves introducing sulfonate onto the fullerenes. The structure and number of polar groups in three fullerene derivatives determined by a series of structural tests greatly affect their hydrophilicity and morphology, resulting in changes in humidity sensitive properties. In particular, the hysteresis and response time of the sensors display a great correlation with hydrophilicity. C60-Ho, the best performing derivative of this work, has exhibited high response values (∼3500 times), good linearity (R2 = 97.3 %), and rapid response/recovery times (0.3/4.4 s), making it suitable for various applications such as non-contact detection of respiration, finger distance, and soil humidity.

C60-CN: A bifunctional interface modification material for perovskite solar cells.

Titanium dioxide (TiO2) is regularly used as an electron transport material in n-i-p perovskite solar cells (PSCs). However, massive defects exist on the TiO2 surface, which will lead to serious hysteresis and interface charge recombination of the device, thus affecting the device's efficiency. In this study, a cyano fullerene pyrrolidine derivative (C60-CN) was synthesized and applied to PSCs for the first time to modify the TiO2 electron transport layer. Systematic studies have shown that the addition of the C60-CN modification layer on the TiO2 surface will enlargement the perovskite grain size, improve the perovskite film quality, enhance electron transport, and reduce charge recombination. The C60-CN layer can significantly reduce the density of trap states in the perovskite solar cells. As a result, the PSCs based on C60-CN/TiO2 obtained a power conversion efficiency (PCE) of 18.60%, suppressing the hysteresis and improving the stability, whereas the PCE of the control device using the original TiO2 ETL was lower, 17.19%.

Efficient Exciton Dislocation and Ultrafast Charge Extraction in CsPbI3 Perovskite Quantum Dots by Using Fullerene Derivative as Semiconductor Ligand.

CsPbI3 quantum dots (QDs) are of great interest in new-generation photovoltaics (PVs) due to their excellent optoelectronic properties. The long and insulative ligands protect their phase stability and enable superior photoluminescence quantum yield, however, limiting charge transportation and extraction in PV devices. In this work, we use a fullerene derivative with the carboxylic anchor group ([SAM]C60) as the semiconductor ligand and build the type II heterojunction system of CsPbI3 QDs and [SAM]C60 molecules. We find their combination enables obvious exciton dislocation and highly efficient photogenerated charge extraction. After the introduction of [SAM]C60, the exciton-binding energy of CsPbI3 decreases from 30 meV to 7 meV and the fluorescence emission mechanism also exhibits obvious changes. Transient absorption spectroscopy visualizes a ~5 ps electron extraction rate in this system. The findings gained here may guide the development of perovskite QD devices.

Highly Active Amino-Fullerene Derivative-Modified TiO2 for Enhancing Formaldehyde Degradation Efficiency under Solar-Light Irradiation.

Formaldehyde (HCHO) is a ubiquitous indoor pollutant that seriously endangers human health. The removal of formaldehyde effectively at room temperature has always been a challenging problem. Here, a kind of amino-fullerene derivative (C60-EDA)-modified titanium dioxide (C60-EDA/TiO2) was prepared by one-step hydrothermal method, which could degrade the formaldehyde under solar light irradiation at room temperature with high efficiency and stability. Importantly, the introduction of C60-EDA not only increases the adsorption of the free formaldehyde molecules but also improves the utilization of sunlight and suppresses photoelectron-hole recombination. The experimental results indicated that the C60-EDA/TiO2 nanoparticles exhibit much higher formaldehyde removal efficiency than carboxyl-fullerene-modified TiO2, pristine TiO2 nanoparticles, and almost all other reported formaldehyde catalysts especially in the aspect of the quality of formaldehyde that is treated by catalyst with unit mass (mHCHO/mcatalyst = 40.85 mg/g), and the removal efficiency has kept more than 96% after 12 cycles. Finally, a potential formaldehyde degradation pathway was deduced based on the situ diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) and reaction intermediates. This work provides some indications into the design and fabrication of the catalysts with excellent catalytic performances for HCHO removal at room temperature.

A bis-pyridinium fullerene derivative induces apoptosis through the generation of ROS in BCR-ABL-positive leukemia cells.

A fusion protein, Breakpoint cluster region-Abelson (BCR-ABL) is responsible for the development of chronic myeloid leukemia (CML) and acute lymphocytic leukemia (ALL). Inhibitors against BCR-ABL are effective for the treatment of leukemia; however, a gatekeeper mutation (T315I) in BCR-ABL results in resistance to these inhibitors, which markedly impedes their efficacy. We herein demonstrated that a bis-pyridinium fullerene derivative (BPF) significantly induced apoptosis in human CML-derived K562 cells and ALL-derived SUP-B15 cells via the generation of reactive oxygen species (ROS). BPF reduced the expression of Bcr-Abl mRNA by inhibiting expression of c-Myc through ROS production. BPF also accelerated protein degradation of BCR-ABL through ROS production. Furthermore, BPF down-regulated the expression of not only BCR-ABL but also T315I-mutated BCR-ABL in ROS-dependent manner. As a result, BPF effectively induced apoptosis in transformed Ba/F3 cells expressing both BCR-ABL and T315I-mutated BCR-ABL. Collectively, these results indicate the potential of BPF as an effective leukemia drug that overcomes resistance to BCR-ABL inhibitors.

Tailored conductive fullerenes-based passivator for efficient and stable inverted perovskite solar cells.

Interfacial defects result in a limitation to the development of highly efficient and stable perovskite solar cells. The passivation of these defects by adopting various interfacial defects passivation agents is a common method for boosting device performance. However, most existing interfacial defects passivation agents form poorly conductive aggregates at the perovskite interface with the electron transport layer (ETL), hindering the transport of charge carriers. In addition, the electron mobility of passivation agents is an important factor that affects the electron communication between the adjacent layers. Herein, a fullerene-based molecular passivator, [60]fullerene-4-(1-(4-(tert-butyl)phenyl)pyrrolidin-2-yl)benzenaminium (C60-tBu-I), is designed and synthesized. This novel n-doping fullerene ammonium iodide is developed as an interfacial modification agent to accelerate charge transport from the perovskite active layer into the ETL while hindering the nonradiative charge carrier recombination. Hence, compared with the control devices (15.66%), C60-tBu-I-modified device presents a higher efficiency of 17.75%. More importantly, the tert-butyl group dramatically enhances the resistance of perovskite films to water molecular. As a result, C60-tBu-I-modified devices exhibit excellent long-term stability, remaining at more than 87% of the initial power conversion efficiency value after storage for 500 h.

Carbohydrate-attached fullerene derivative for selective localization in ordered carbohydrate-block-poly(3-hexylthiophene) nanodomains.

A carbohydrate-based fullerene derivative (AcMal7-C61) is designed, synthesized and applied to a lamellar-forming high-χ block copolymer system, poly(3-hexylthiophene)-block-peracetylated maltoheptaose (P3HT-b-AcMal7), to actualize an ordered donor/acceptor (D/A) network. A well-defined D/A lamellar structure of the P3HT-b-AcMal7:AcMal7-C61 blend with sub-10 nm domain features is achieved upon thermal annealing. The AcMal7-C61 molecules are localized in the phase-separated AcMal7 nanodomains without causing the formation of fullerene crystals while maintaining the lamellar morphology up to 1:0.5 (D:A) blending ratio. The cross-sectional TEM observation and GISAXS measurement reveals that the P3HT-b-AcMal7 tends to spontaneously organize into lamellar structures oriented perpendicular to the film surface at the air/film interface while the domain orientation at the bottom interface depends on the nature of the substrate.

Structural basis of fullerene derivatives as novel potent inhibitors of protein acetylcholinesterase without catalytic active site interaction: insight into the inhibitory mechanism through molecular modeling studies.

Acetylcholinesterase (AChE) is an important kind of esterase that plays a key biological role in the central and peripheral nervous systems. Recent research has demonstrated that some fullerene derivatives serve as a new nanoscale class of potent inhibitors of AChE, but the specific inhibition mechanism remains unclear. In the present article, several molecular modeling methods, such as molecular docking, molecular dynamics simulations and molecular mechanics/generalized Born surface area calculations, were used for the investigation of the binding mode and inhibition mechanism of fullerene inhibitions for AChE. Results revealed that fullerene inhibitors block the entrance of substrates by binding with the peripheral anionic site (PAS) region. Thus, fullerene derivatives might mainly serve as competitive inhibitors. The interactions of a fullerene backbone with AChE are at the same level in different single side chain systems and seem to be related to the length or aromaticity of the side chain. The inhibitor with multihydroxyl side chains shows an obviously large electrostatic interaction as it forms additional hydrogen bonds with AChE. Moreover, fullerene derivatives might exhibit noncompetitive inhibition partly by affecting some secondary structures around them. Thus, the destructions of these secondary structures can lead to conformational changes in some important regions, such as the catalytic triad and acyl pocket. The investigation is of great importance to the discovery of good fullerene inhibitors.Communicated by Ramaswamy H. Sarma.

Carnosine-Modified Fullerene as a Highly Enhanced ROS Scavenger for Mitigating Acute Oxidative Stress.

Fullerenes are known as highly efficient scavengers for reactive oxygen species (ROSs). In this study, a carnosine-modified fullerene derivative (C60-Car) was synthesized via a one-step nucleophilic addition reaction. C60-Car forms nanoparticles (NPs) readily in water at neutral pH and room temperature through self-assembly. The C60-Car NPs were found to possess good water solubility, biocompatibility, and excellent ROSs scavenging capability. The scavenging efficiency of ROSs is as high as 92.49% and significantly better than that of hydroxyfullerene (C60-OH NPs, 70.92%) and l-carnosine. Furthermore, C60-Car NPs showed strong cytoprotective ability against H2O2-induced damage to the normal human fetal hepatocyte cells (L-02) and human epidermal keratinocytes-adult (HEK-a) cells at a lower concentration of 2.5 µM. In contrast, C60-OH NPs showed a minor cytoprotective effect on cells at a high concentration of 10 µM. The excellent properties of such a fullerene derivative, C60-Car, can be attributed largely to the involvement of l-carnosine with biological activity and antioxidant property, which make it better for biomedicine, and it may provide a new strategy for mitigating acute oxidative stress based on fullerene materials.

Over 15% Efficiency in Ternary Organic Solar Cells by Enhanced Charge Transport and Reduced Energy Loss.

In this study, an efficient ternary bulk-heterojunction (BHJ) organic solar cell (OSC) is demonstrated by incorporating two acceptors, PC61BM and ITC6-4F, with a polymer donor (PM6). This reveals that the addition of PC61BM not only enhances the electron mobility of the derived BHJ blend but also facilitates exciton dissociation, resulting in a more balanced charge transport alongside with reduced trap-assisted charge recombination. Consequently, as compared to the pristine PM6/ITC6-4F device, the optimal ternary OSC is revealed to deliver an improved power conversion efficiency (PCE) of 15.11% with a boosted JSC, VOC, and fill factor (FF) simultaneously. The resultant VOC and FF are among the highest values recorded in the literature for the ternary OSCs with a PCE exceeding 15%. This result thus suggests that besides improving the charge transport characteristics in devices, incorporating a fullerene derivative as part of the acceptor can also improve the resultant VOC, which can reduce the energy loss to realize efficient organic photovoltaics.

Improved Performance of Planar Perovskite Solar Cells Using an Amino-Terminated Multifunctional Fullerene Derivative as the Passivation Layer.

Organic-inorganic metal-halide perovskite solar cells (PSCs) have been revolutionizing the photovoltaic (PV) community in the past decade. However, the trap states in TiO2 as the electron-transport layer seriously affect the device PV performance and stability. Here, we design and synthesize a fullerene derivative C60NH2 featuring an amino-terminated group. We use C60NH2 as a passivation layer between TiO2 and perovskite in planar PSCs with a standard configuration to improve the quality of the obtained perovskite film as well as the electron-transfer efficiency, resulting in an obvious increment of PV performance and stability of the devices. The champion power conversion efficiency of 18.34% is achieved under 100 mW cm-2 illumination utilizing C60NH2 as the passivation layer with much less hysteresis. Planar PSCs demonstrate superior stability under natural sunlight and 40-50% relative humidity after C60NH2 passivation. This work enriches the choices of materials for interface engineering toward fabrication of planar PSCs with high performance.

Optoelectronic Properties of C60 and C70 Fullerene Derivatives: Designing and Evaluating Novel Candidates for Efficient P3HT Polymer Solar Cells.

Ten novel fullerene-derivatives (FDs) of C60 and C70 had been designed as acceptor for polymer solar cell (PSC) by employing the quantitative structure-property relationship (QSPR) model, which was developed strategically with a reasonably big pool of experimental power conversion efficiency (PCE) data. The QSPR model was checked and validated with stringent parameter and reliability of predicted PCE values of all designed FDs. They were assessed by the applicability domain (AD) and process randomization test. The predicted PCE of FDs range from 7.96 to 23.01. The obtained encouraging results led us to the additional theoretical analysis of the energetics and UV-Vis spectra of isolated dyes employing Density functional theory (DFT) and Time-dependent-DFT (TD-DFT) calculations using PBE/6-31G(d,p) and CAM-B3LYP/6-311G(d,p) level calculations, respectively. The FD4 is the best C60-derivatives candidates for PSCs as it has the lowest exciton binding energy, up-shifted lowest unoccupied molecular orbital (LUMO) energy level to increase open-circuit voltage (VOC) and strong absorption in the UV region. In case of C70-derivatives, FD7 is potential candidate for future PSCs due to its strong absorption in UV-Vis region and lower exciton binding energy with higher VOC. Our optoelectronic results strongly support the developed QSPR model equation. Analyzing QSPR model and optoelectronic parameters, we concluded that the FD1, FD2, FD4, and FD10 are the most potential candidates for acceptor fragment of fullerene-based PSC. The outcomes of tactical molecular design followed by the investigation of optoelectronic features are suggested to be employed as a significant resource for the synthesis of FDs as an acceptor of PSCs.

Fullerene Derivative-Modified SnO2 Electron Transport Layer for Highly Efficient Perovskite Solar Cells with Efficiency over 21.

Tin dioxide (SnO2) has been widely applied as an electron transport layer (ETL) for the n-i-p-type perovskite solar cells (Pero-SCs). However, the existence of defects at the surface of SnO2 and the hysteresis behavior of the devices with SnO2 ETL limit its application in the Pero-SCs. In this study, a fullerene derivative pyrrolidinofullerene C60-substituted phenol (NPC60-OH) was synthesized and applied to modify the SnO2 ETL in Pero-SCs for the first time. The systematic and comparative characterizations demonstrated that, after the introduction of an NPC60-OH modification layer on the SnO2 ETL, the perovskite films in the corresponding device showed enlarged grain size and these devices presented enhanced electron transport and decreased charge recombination velocity. Besides, the NPC60-OH layer could significantly reduce the trap-state density in the perovskite film. As a result, a champion power conversion efficiency (PCE) of 21.39% was achieved for the SnO2/NPC60-OH-based Pero-SCs, with suppressed hysteresis and improved stability, while the control devices with pristine SnO2 ETL showed a lower PCE of 19.04%.

A Multifunctional Bis-Adduct Fullerene for Efficient Printable Mesoscopic Perovskite Solar Cells.

Printable mesoscopic perovskite solar cells (PMPSCs) have exhibited great attractive prospects in the energy conversion field due to their high stability and potential scalability. However, the thick perovskite film in the mesoporous layers challenges the charge transportation and increase grain boundary defects, limiting the performance of the PMPSCs. It is critical not only to improve the electric property of the perovskite film but also to passivate the charge traps to improve the device performance. Herein we synthesized a bis-adduct 2,5-(dimethyl ester) C60 fulleropyrrolidine (bis-DMEC60) via a rational molecular design and incorporated it into the PMPSCs. The enhanced chemical interactions between perovskite and bis-DMEC60 improve the conductivity of the perovskite film as well as elevate the passivation effect of bis-DMEC60 at the grain boundaries. As a result, the fill factor (FF) and power conversion efficiency (PCE) of the PMPSCs containing bis-DMEC60 reached 0.71 and 15.21%, respectively, significantly superior to the analogous monoadduct derivative (DMEC60)-containing and control devices. This work suggests that fullerene derivatives with multifunctional groups are promising for achieving high-performance PMPSCs.