Dopant-additive synergism enhances perovskite solar modules.

Perovskite solar cells (PSCs) are among the most promising photovoltaic technologies owing to their exceptional optoelectronic properties1,2. However, the lower efficiency, poor stability and reproducibility issues of large-area PSCs compared with laboratory-scale PSCs are notable drawbacks that hinder their commercialization3. Here we report a synergistic dopant-additive combination strategy using methylammonium chloride (MACl) as the dopant and a Lewis-basic ionic-liquid additive, 1,3-bis(cyanomethyl)imidazolium chloride ([Bcmim]Cl). This strategy effectively inhibits the degradation of the perovskite precursor solution (PPS), suppresses the aggregation of MACl and results in phase-homogeneous and stable perovskite films with high crystallinity and fewer defects. This approach enabled the fabrication of perovskite solar modules (PSMs) that achieved a certified efficiency of 23.30% and ultimately stabilized at 22.97% over a 27.22-cm2 aperture area, marking the highest certified PSM performance. Furthermore, the PSMs showed long-term operational stability, maintaining 94.66% of the initial efficiency after 1,000 h under continuous one-sun illumination at room temperature. The interaction between [Bcmim]Cl and MACl was extensively studied to unravel the mechanism leading to an enhancement of device properties. Our approach holds substantial promise for bridging the benchtop-to-rooftop gap and advancing the production and commercialization of large-area perovskite photovoltaics.

Homogenizing out-of-plane cation composition in perovskite solar cells.

Perovskite solar cells with the formula FA1-xCsxPbI3, where FA is formamidinium, provide an attractive option for integrating high efficiency, durable stability and compatibility with scaled-up fabrication. Despite the incorporation of Cs cations, which could potentially enable a perfect perovskite lattice1,2, the compositional inhomogeneity caused by A-site cation segregation is likely to be detrimental to the photovoltaic performance of the solar cells3,4. Here we visualized the out-of-plane compositional inhomogeneity along the vertical direction across perovskite films and identified the underlying reasons for the inhomogeneity and its potential impact for devices. We devised a strategy using 1-(phenylsulfonyl)pyrrole to homogenize the distribution of cation composition in perovskite films. The resultant p-i-n devices yielded a certified steady-state photon-to-electron conversion efficiency of 25.2% and durable stability.

Enhanced Charge Transfer in Quasi-2D Perovskite by Formamidinium Cation Gradient Incorporation for Efficient and Stable Solar Cells.

Quasi-2D perovskites have attracted much attention in perovskite photovoltaics due to their excellent stability. However, their photoelectric conversion efficiency (PCE) still lags 3D counterparts, particularly with high short-circuit current (JSC) loss. The quantum confinement effect is pointed out to be the sole reason, which introduces widened bandgap and poor exciton dissociation, and undermines the light capture and charge transport. Here, the gradient incorporation of formamidinium (FA) cations into quasi-2D perovskite is proposed to address this issue. It is observed that FA prefers to incorporate into the larger n value phases near the film surface compared to the smaller n value phases in the bulk, resulting in a narrow bandgap and gradient structure within the film. Through charge dynamic analysis using in situ light-dark Kelvin probe force microscopy and transient absorption spectroscopy, it is demonstrated that incorporating 10% FA significantly facilitates efficient charge transfer between low n-value phases in the bulk and high n-value nearby film surface, leading to reduced charge accumulation. Ultimately, the device based on (AA)2(MA0.9FA0.1)4Pb5I16, where AA represents n-amylamine renowned for its exceptional environmental stability as a bulky organic ligand, achieves an impressive power conversion efficiency (PCE) of 18.58% and demonstrates enhanced illumination and thermal stability.

Dopant-Free Pyrene-Based Hole Transporting Material Enables Efficient and Stable Perovskite Solar Cells.

Dopant-free hole transporting materials (HTMs) is significant to the stability of perovskite solar cells (PSCs). Here, we developed a novel star-shape arylamine HTM, termed Py-DB, with a pyrene core and carbon-carbon double bonds as the bridge units. Compared to the reference HTM (termed Py-C), the extension of the planar conjugation backbone endows Py-DB with typical intermolecular π-π stacking interactions and excellent solubility, resulting in improved hole mobility and film morphology. In addition, the lower HOMO energy level of the Py-DB HTM provides efficient hole extraction with reduced energy loss at the perovskite/HTM interface. Consequently, an impressive power conversion efficiency (PCE) of 24.33 % was achieved for dopant-free Py-DB-based PSCs, which is the highest PCE for dopant-free small molecular HTMs in n-i-p configured PSCs. The dopant-free Py-DB-based device also exhibits improved long-term stability, retaining over 90 % of its initial efficiency after 1000 h exposure to 25 % humidity at 60 °C. These findings provide valuable insights and approaches for the further development of dopant-free HTMs for efficient and reliable PSCs.

Extending the π-Conjugated System in Spiro-Type Hole Transport Material Enhances the Efficiency and Stability of Perovskite Solar Modules.

Hole transport materials (HTMs) are a key component of perovskite solar cells (PSCs). The small molecular 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenyl)-amine-9,9'-spirobifluorene (spiro-OMeTAD, termed "Spiro") is the most successful HTM used in PSCs, but its versatility is imperfect. To improve its performance, we developed a novel spiro-type HTM (termed "DP") by substituting four anisole units on Spiro with 4-methoxybiphenyl moieties. By extending the π-conjugation of Spiro in this way, the HOMO level of the HTM matches well with the perovskite valence band, enhancing hole mobility and increasing the glass transition temperature. DP-based PSC achieves high power conversion efficiencies (PCEs) of 25.24 % for small-area (0.06 cm2 ) devices and 21.86 % for modules (designated area of 27.56 cm2 ), along with the certified efficiency of 21.78 % on a designated area of 27.86 cm2 . The encapsulated DP-based devices maintain 95.1 % of the initial performance under ISOS-L-1 conditions after 2560 hours and 87 % at the ISOS-L-3 conditions over 600 hours.

Dopant-Free Hole Transport Materials Afford Efficient and Stable Inorganic Perovskite Solar Cells and Modules.

The emerging CsPbI3 perovskites are highly efficient and thermally stable materials for wide-band gap perovskite solar cells (PSCs), but the doped hole transport materials (HTMs) accelerate the undesirable phase transition of CsPbI3 in ambient. Herein, a dopant-free D-π-A type HTM named CI-TTIN-2F has been developed which overcomes this problem. The suitable optoelectronic properties and energy-level alignment endow CI-TTIN-2F with excellent charge collection properties. Moreover, CI-TTIN-2F provides multisite defect-healing effects on the defective sites of CsPbI3 surface. Inorganic CsPbI3 PSCs with CI-TTIN-2F HTM feature high efficiencies up to 15.9 %, along with 86 % efficiency retention after 1000 h under ambient conditions. Inorganic perovskite solar modules were also fabricated that exhibiting an efficiency of 11.0 % with a record area of 27 cm2 . This work confirms that using efficient dopant-free HTMs is an attractive strategy to stabilize inorganic PSCs for their future scale-up.

Colloidal Synthesis of Air-Stable Alloyed CsSn1-xPbxI3 Perovskite Nanocrystals for Use in Solar Cells.

Organic-inorganic hybrid perovskite solar cells have demonstrated unprecedented high power conversion efficiencies in the past few years. Now, the universal instability of the perovskites has become the main barrier for this kind of solar cells to realize commercialization. This situation can be even worse for those tin-based perovskites, especially for CsSnI3, because upon exposure to ambient atmosphere the desired black orthorhombic phase CsSnI3 would promptly lose single crystallinity and degrade to the inactive yellow phase, followed by irreversible oxidation into metallic Cs2SnI6. By alloying CsSnI3 with CsPbI3, we herein report the synthesis of alloyed perovskite quantum dot (QD), CsSn1-xPbxI3, which not only can be phase-stable for months in purified colloidal solution but also remains intact even directly exposed to ambient air, far superior to both of its parent CsSnI3 and CsPbI3 QDs. Ultrafast transient absorption spectroscopy studies reveal that the photoexcited electrons in the alloyed QDs can be injected into TiO2 nanocrystals at a fast rate of 1.12 × 1011 s-1, which enables a high photocurrent generation in solar cells.

Morphology Engineering for High-Performance and Multicolored Perovskite Light-Emitting Diodes with Simple Device Structures.

The film morphology is extremely significant for solution processed perovskite devices. Through fine morphology engineering without using any additives or further posttreatments, a full-coverage and high quantum yield perovskite film has been achieved based on one-step spin-coating method. The morphologies and film characteristics of MAPbBr3 with different MABr:PbBr2 starting material ratios are in-depth investigated by scanning electron microscopy, atomic force microscopy, X-ray diffraction, photoluminescence, and time resolved photoluminescence. High performance organometal halide perovskite light-emitting didoes (PeLEDs) based on simple device structure of indium tin oxide/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate ( PEDOT: PSS)/perovskite/TPBi/Ca/Al are demonstrated. The green PeLED based on MAPbBr3 shows a maximum luminance of 8794 cd m(-2) (at 7.3 V) and maximum current efficiency of 5.1 cd A(-1) (at 5.1 V). Furthermore, a class of hybrid PeLEDs by adjusting the halide ratios of methylammonium lead halide (MAPbX3 , where X is Cl, Br, or I) are also demonstrated at room temperature. These mix-halogenated PeLEDs show bright luminance (above 100 cd m(-) (2) ) with narrow and clean emission bands over the wide color gamut.

TiO2 hierarchical sub-wavelength microspheres for high efficiency dye-sensitized solar cells.

Monodisperse anatase hierarchical microspheres were produced via a simple sol-gel process. These microspheres in the sub-wavelength diameter of 320-750 nm could scatter visible light efficiently as whispering gallery modes (WGM) corresponding to the dye sensitized wavelength, and load a large number of dye molecules with a large surface area (149.82 m2 g-1). Dye-sensitized solar cells (DSCs) based on the microsphere monolayer adsorbed light fully over the entire wavelength region and facilitated electrolyte diffusion due to larger voids between the microspheres, compared to the conventional film. Furthermore, the dynamics of electron transport and recombination was investigated systematically, indicating the higher charge collection efficiency of the TiO2 microsphere film. Overall, DSCs based on the 7.5 µm hierarchical microsphere monolayer exhibited more outstanding photovoltaic performances, yielding a high power conversion efficiency (PCE) of 11.43% under simulated AM 1.5 sunlight. Half of the normal film thickness was used to cut the device cost significantly.

Effect of electron-donor ancillary ligands on the heteroleptic ruthenium complexes: synthesis, characterization, and application in high-performance dye-sensitized solar cells.

Three heteroleptic ruthenium complexes, RC-15, RC-16 and RC-22, with sulfur- or oxygen-containing electron-donor, phenylpyridine-based ancillary ligands, are synthesized. The influence of the different electron donors-the acyclic electron donors methylthio and methoxyl, and the cyclic electron donor methylenedioxy-on the photophysical and electrochemical behavior in dye sensitizers and photovoltaic performance in DSSCs are investigated. Compared to the conventional dye N3, all the dyes demonstrate superior performance in the form of molar absorptivity, photocurrent density (J(SC)) and conversion efficiency (η). The DSSCs based on RC-15 and RC-16, with only a two-atom change in the acyclic electron donor, exhibit analogous photovoltaic performance (9.28% for RC-15 and 9.32% for RC-16). The highest photocurrent density (19.06 mA cm(-2)) and conversion efficiency (9.74%) are recorded for RC-22, which contains the cyclic electron donor. Transient absorption (TAS) and time-resolved photoluminescence (TRPL) measurements are carried out to investigate the sensitizers' regeneration and the behavior of excited electron decay kinetics. Furthermore, electrochemical impedance spectroscopy (EIS) is operated to explain the charge recombination and the electron lifetime. These consequences reveal substantial dependences on the different configurations of the electron-donor ancillary ligands.

Mesoporous TiO2 Nanowire Film for Dye-Sensitized Solar Cell.

In this work, TiO2 nanowire arrays were grown on fluorine-doped tin oxide (FTO) glass substrate, and then were converted into mesoporous nanowires (MNWs). The TiO2 MNWs are about 5 µm in length and 30-200 nm in diameter, with mesopores size of 5-30 nm randomly distributed on the NW surface. X-ray diffraction pattern reports show that the NWs are single crystallized rutile TiO2 and oriented grown along [001]. Through further characterization of FT-IR and TG-DSC, we proposed a reasonable explanation for pore existence. After dye-sensitized solar cells (DSSCs) assembly, the photoelectric conversion efficiency (PCE) of MNWs based DSSC achieved 3.2%. It means tenfold enhancement of photoelectric property compare with the as-grown NWs. Furthermore, dye absorb capacity of MNWs can reach up to 4.11 x 10(-8) mol/cm2. However, such MNWs can not only provide quick and efficient electron transmission channel, but also owns big specific surface area to absorb abundant dyes, thus conducive to fabricate solar cell with a high PCE.

TiO(2) nanospheres: a facile size-tunable synthesis and effective light-harvesting layer for dye-sensitized solar cells.

A facile route to synthesize amorphous TiO2 nanospheres by a controlled oxidation and hydrolysis process without any structure-directing agents or templates is presented. The size of the amorphous TiO2 nanospheres can be easily turned from 20 to 1500 nm by adjusting either the Ti species or ethanol content in the reaction solution. The phase structure of nanospheres can be controlled by hydrothermal treatment. The TiO2 nanospheres show excellent size-dependent light-scattering effects and can be structured into a light-harvesting layer for dye-sensitized solar cells with a quite high power conversion efficiency of 9.25 %.

Research progress on the improvement of cardiovascular diseases through the autonomic nervous system regulation of the NLRP3 inflammasome pathway.

Cardiovascular disease stands as a leading global cause of mortality. Nucleotide-binding Oligomerization Domain-like Receptor Protein 3 (NLRP3) inflammasome is widely acknowledged as pivotal factor in specific cardiovascular disease progression, such as myocardial infarction, heart failure. Recent investigations underscore a close interconnection between autonomic nervous system (ANS) dysfunction and cardiac inflammation. It has been substantiated that sympathetic nervous system activation and vagus nerve stimulation (VNS) assumes critical roles withinNLRP3 inflammasome pathway regulation, thereby contributing to the amelioration of cardiac injury and enhancement of prognosis in heart diseases. This article reviews the nexus between NLRP3 inflammasome and cardiovascular disorders, elucidating the modulatory functions of the sympathetic and vagus nerves within the ANS with regard to NLRP3 inflammasome. Furthermore, it delves into the potential therapeutic utility of NLRP3 inflammasome to be targeted by VNS. This review serves as a valuable reference for further exploration into the potential mechanisms underlying VNS in the modulation of NLRP3 inflammasome.

A Multifunctional Dye Molecule as the Interfacial Layer for Perovskite Solar Cells.

In perovskite solar cells (PSCs), defects in the interface and mismatched energy levels can damage the device performance. Improving the interface quality is an effective way to achieve efficient and stable PSCs. In this work, a multifunctional dye molecule, named ThPCyAc, was designed and synthesized to be introduced in the perovskite/HTM interface. On one hand, various functional groups on the acceptor unit can act as Lewis base to reduce defect density and suppress nonradiative combinations. On the other hand, the stepwise energy-level alignment caused by ThPCyAc decreases the accumulation of interface carriers for facilitating charge extraction and transmission. Therefore, based on the ThPCyAc molecule, the devices exhibit elevated open-circuit voltage and fill factor, resulting in the best power conversion efficiency (PCE) of 23.16%, outperforming the control sample lacking the interface layer (PCE = 21.49%). Excitingly, when attempting to apply it as a self-assembled layer in inverted devices, ThPCyAc still exhibits attractive behavior. It is worth noting that these results indicate that dye molecules have great potential in developing multifunctional interface materials to obtain higher-performance PSCs.

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) 2,2',7,7'-tetrakis(N, N-di-p-methoxyphenylamino)-9,9'-spirobifluorene (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 HTM, termed FTPE-ST, with a twist conjugated dibenzo(g,p)chrysene core and coplanar 3,4-ethylenedioxythiophene (EDOT) as extended donor units, is designed to enhance π-π interactions, without compromising on solubility. The three-dimensional (3D) configuration provides the material multi-direction charge transport as well as excellent solubility even in 2-methylanisole, and its large conjugated backbone endows the HTM with a high hole mobility. Moreover, the sulfur donors in EDOT units coordinate with 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 achieve a champion power conversion efficiency (PCE) of 25.21% with excellent long-time stability, 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.

Highly Efficient and Stable FAPbI3 Perovskite Solar Cells and Modules Based on Exposure of the (011) Facet.

Perovskite crystal facets greatly impact the performance and stability of their corresponding photovoltaic devices. Compared to the (001) facet, the (011) facet yields better photoelectric properties, including higher conductivity and enhanced charge carrier mobility. Thus, achieving (011) facet-exposed films is a promising way to improve device performance. However, the growth of (011) facets is energetically unfavorable in FAPbI3 perovskites due to the influence of methylammonium chloride additive. Here, 1-butyl-4-methylpyridinium chloride ([4MBP]Cl) was used to expose (011) facets. The [4MBP]+ cation selectively decreases the surface energy of the (011) facet enabling the growth of the (011) plane. The [4MBP]+ cation causes the perovskite nuclei to rotate by 45° such that (011) crystal facets stack along the out-of-plane direction. The (011) facet has excellent charge transport properties and can achieve better-matched energy level alignment. In addition, [4MBP]Cl increases the activation energy barrier for ion migration, suppressing decomposition of the perovskite. As a result, a small-size device (0.06 cm2) and a module (29.0 cm2) based on exposure of the (011) facet achieved power conversion efficiencies of 25.24% and 21.12%, respectively.

Retarding solid-state reactions enable efficient and stable all-inorganic perovskite solar cells and modules.

All-inorganic CsPbI3 perovskite solar cells (PSCs) with efficiencies exceeding 20% are ideal candidates for application in large-scale tandem solar cells. However, there are still two major obstacles hindering their scale-up: (i) the inhomogeneous solid-state synthesis process and (ii) the inferior stability of the photoactive CsPbI3 black phase. Here, we have used a thermally stable ionic liquid, bis(triphenylphosphine)iminium bis(trifluoromethylsulfonyl)imide ([PPN][TFSI]), to retard the high-temperature solid-state reaction between Cs4PbI6 and DMAPbI3 [dimethylammonium (DMA)], which enables the preparation of high-quality and large-area CsPbI3 films in the air. Because of the strong Pb-O contacts, [PPN][TFSI] increases the formation energy of superficial vacancies and prevents the undesired phase degradation of CsPbI3. The resulting PSCs attained a power conversion efficiency (PCE) of 20.64% (certified 19.69%) with long-term operational stability over 1000 hours. A record efficiency of 16.89% for an all-inorganic perovskite solar module was achieved, with an active area of 28.17 cm2.

A N-Ethylcarbazole-Terminated Spiro-Type Hole-Transporting Material for Efficient and Stable Perovskite Solar Cells.

The development of stable and efficient hole-transporting materials (HTMs) is critical for the commercialization of perovskite solar cells (PSCs). Herein, a novel spiro-type HTM was designed and synthesized where N-ethylcarbazole-terminated groups fully substituted the methoxy group of spiro-OMeTAD, named spiro-carbazole. The developed molecule exhibited a lower highest occupied molecular orbital level, higher hole mobility, and extremely high glass transition temperature (Tg =196 °C) compared with spiro-OMeTAD. PSCs with the developed molecule exhibited a champion power conversion efficiency (PCE) of 22.01 %, which surpassed traditional spiro-OMeTAD (21.12 %). Importantly, the spiro-carbazole-based device had dramatically better thermal, humid, and long-term stability than spiro-OMeTAD.

Single-crystalline TiO2 nanoparticles for stable and efficient perovskite modules.

Despite the remarkable progress in power conversion efficiency of perovskite solar cells, going from individual small-size devices into large-area modules while preserving their commercial competitiveness compared with other thin-film solar cells remains a challenge. Major obstacles include reduction of both the resistive losses and intrinsic defects in the electron transport layers and the reliable fabrication of high-quality large-area perovskite films. Here we report a facile solvothermal method to synthesize single-crystalline TiO2 rhombohedral nanoparticles with exposed (001) facets. Owing to their low lattice mismatch and high affinity with the perovskite absorber, their high electron mobility and their lower density of defects, single-crystalline TiO2 nanoparticle-based small-size devices achieve an efficiency of 24.05% and a fill factor of 84.7%. The devices maintain about 90% of their initial performance after continuous operation for 1,400 h. We have fabricated large-area modules and obtained a certified efficiency of 22.72% with an active area of nearly 24 cm2, which represents the highest-efficiency modules with the lowest loss in efficiency when scaling up.

A study on formation of titanium oxide nanoribbons.

The transformation process of nanoribbons produced by the hydrothermal treatment in 10 M NaOH solution at 200 degrees C was investigated systematically via electron microscopy. Field emission scanning electron microscope (FE-SEM) observation showed that the treatment duration had a strong effect on the product morphology from the hollow nanotubes to nanoribbons. The details of transformation were studied by transmission electron miscroscopy. Some nanotubes assembled into clusters and grew into nanowires as the grain to form the nanoribbons, whilemost of nanotubes dissolved into the solution again.