Accuracy of implant height and width measurement with triaxial rotation method based on cone-beam CT.

Objective: To investigate the accuracy of implant height and width measurement in the mandibular and maxillary first molar region based on cone-beam CT (CBCT) data, and to establish an accurate method for bone measurement in the implant region. Materials and methods: CBCT images of 122 patients with implant in mandibular or maxillary first molar region were retrospectively collected. Two methods were used to measure sagittal height (SH), coronal height (CH), sagittal width (SW), and coronal width (CW) of implants. Method 1 (general method): the images were analyzed using the built-in software NNT 9.0 software. SHl, CHl, SWl, and CWl were measured on the reconstructed sagittal and coronal based on the radiologist's own experience. Method 2 (triaxial rotation method): the raw data were demonstrated in Expert mode of NNT 9.0 software, in which the coronal axis and sagittal axis were rotated paralleling to the long axis of the implant for reconstruction, and then SH2, CH2, SW2, and CW2 were measured on the reconstructed sagittal and coronal images. The results of two methods were compared with the actual implant size (H0, W0). Paired T-test was performed for statistical analysis. Dahlberg formula was used to check the measurement error. Results: For method 1, there was no significant differences between SHl and H0 (P > 0.05), but significant differences between CHl and H0, SWl and W0, and CWl and W0 (P < 0.05). For method 2, there were no significant differences between all measurements and actual size (P > 0.05). The random error range measured using Dahlberg formula was 0.157-1.171 mm for general method and 0.017-0.05 mm for triaxial rotation method. Conclusion: The triaxial rotation method is accurate for implant height and width measurements on CBCT images and could be used in pre-operatively bone height and width measurement of potential implant sites.

Controlled Nucleation and Oriented Crystallization of Methylammonium-Free Perovskites via In Situ Generated 2D Perovskite Phases.

Enhancing stability while maintaining high efficiency is among the primary challenges in the commercialization of perovskite solar cells (PSCs). Here, a crystal growth technique assisted by in situ generated 2D perovskite phases has been developed to construct high-quality 2D/3D perovskite films. The in situ generated 2D perovskite serve as templates for regulating the nucleation and oriented crystal growth in the α-FAPbI3-rich film. This led to a high film quality with much reduced trap density and an ultralong carrier lifetime. The obtained perovskite film shows excellent stability under extreme environment conditions (T = 200 °C, RH = 75 ± 5%). The corresponding PSC achieved an efficiency of 26.16% (certified 25.84%), along with excellent operational stability (T93 > 1300 h, T ≅ 50 °C) as well as outstanding high and low temperature cycle stability.

Unveiling Local Current Behavior and Manipulating Grain Homogenization of Perovskite Films for Efficient Solar Cells.

Achieving high power conversion efficiency in perovskite solar cells (PSCs) heavily relies on fabricating homogeneous perovskite films. However, understanding microscopic-scale properties such as current generation and open-circuit voltage within perovskite crystals has been challenging due to difficulties in quantifying intragrain behavior. In this study, the local current intensity within state-of-the-art perovskite films mapped by conductive atomic force microscopy reveals a distinct heterogeneity, which exhibits a strong anticorrelation to the external biases. Particularly under different external bias polarities, specific regions in the current mapping show contrasting conductivity. Moreover, grains oriented differently exhibit varied surface potentials and currents, leading us to associate this local current heterogeneity with the grain orientation. It was found that the films treated with isopropanol exhibit ordered grain orientation, demonstrating minimized lattice heterogeneity, fewer microstructure defects, and reduced electronic disorder. Importantly, devices exhibiting an ordered orientation showcase elevated macroscopic optoelectronic properties and boosted device performance. These observations underscore the critical importance of fine-tuning the grain homogenization of perovskite films, offering a promising avenue for further enhancing the efficiency of PSCs.

Dipole Moments Regulation of Biphosphonic Acid Molecules for Self-assembled Monolayers Boosts the Efficiency of Organic Solar Cells Exceeding 19.7.

PEDOT: PSS has been widely used as a hole extraction layer (HEL) in organic solar cells (OSCs). However, their acidic nature can potentially corrode the indium tin oxide (ITO) electrode over time, leading to adverse effects on the longevity of the OSCs. Herein, we have developed a class of biphosphonic acid molecules with tunable dipole moments for self-assembled monolayers (SAMs), namely, 3-BPIC(i), 3-BPIC, and 3-BPIC-F, which exhibit an increasing dipole moment in sequence. Compared to centrosymmetric 3-BPIC(i), the axisymmetric 3-BPIC and 3-BPIC-F exhibit higher adsorption energies (Eads) with ITO, shorter interface spacing, more uniform coverage on ITO surface, and better interfacial compatibility with the active layer. Thanks to the incorporation of fluorine atoms, 3-BPIC-F exhibits a deeper highest occupied molecular orbital (HOMO) energy level and a larger dipole moment compared to 3-BPIC, resulting in an enlarged work function (WF) for the ITO/3-BPIC-F substrate. These advantages of 3-BPIC-F could not only improve hole extraction within the device but also lower the interfacial impedance and reduce nonradiative recombination at the interface. As a result, the OSCs using SAM based on 3-BPIC-F obtained a record high efficiency of 19.71%, which is higher than that achieved from the cells based on 3-BPIC(i) (13.54%) and 3-BPIC (19.34%). Importantly, 3-BPIC-F-based OSCs exhibit significantly enhanced stability compared to that utilizing PEDOT:PSS as HEL. Our work offers guidance for the future design of functional molecules for SAMs to realize even higher performance in organic solar cells.

The exploration of a compound cone-beam CT contrast agent for diagnosis of human extracted cracked tooth.

Objectives: This study aims to investigate the use of sodium iodide (NaI), dimethyl sulfoxide (DMSO), ethyl alcohol, and ethyl acetate as cone-beam CT (CBCT) contrast agents for diagnosing cracked teeth. The optimal delay time for detecting the number of crack lines beyond the dentino-enamel junction (Nd), the number of cracks extending from the occlusal surface to the pulp cavity (Np), and the depth of the crack lines was explored. Methods: 14 human extracted cracked teeth were collected, 12 were used for enhanced scanning, and 2 were used for exploring the characteristic of crack lines. The teeth were scanned in 3 CBCT enhanced scanning (ES) modes: ES1 using meglumine diatrizoate (MD); ES2 using NaI and DMSO, ES3 using NaI, DMSO, ethyl alcohol and ethyl acetate. Three delay times (15mins, 30mins, and 60mins) were set for scanning. Nd, Np, and depth of crack lines were evaluated. Results: There were totally 24 crack lines on 12 cracked teeth. Nd was 10 in ES1 at 60mins, 24 in ES2 at 60mins and 24 in ES3 at 15mins. Np was 1 in ES1 at 60mins, 10 in ES2 at 60mins and 21 in ES3 at 60mins, and there were significantly different among them (p < 0.01). The average depth presented on ES3 was significantly deeper than ES1 and ES2 (p < 0.01). Conclusion: NaI, DMSO, ethyl alcohol and ethyl acetate show potential as contrast agents for enhanced CBCT scanning in diagnosis of cracked teeth and their depth in vivo. A delay time of 15 min is necessary to confirm the existence of crack lines, while a longer delay time is required to ascertain if these crack lines extend to the pulp cavity.

[Ligusticum cycloprolactam inhibits IL-1ß-induced apoptosis and inflammation of rat chondrocytes via HMGB1/TLR4/NF-κB signaling pathway].

Chondrocytes are unique resident cells in the articular cartilage, and the pathological changes of them can lead to the occurrence of osteoarthritis(OA). Ligusticum cycloprolactam(LIGc) are derivatives of Z-ligustilide(LIG), a pharmacodynamic marker of Angelica sinensis, which has various biological functions such as anti-inflammation and inhibition of cell apoptosis. However, its protective effect on chondrocytes in the case of OA and the underlying mechanism remain unclear. This study conducted in vitro experiments to explore the molecular mechanism of LIGc in protecting chondrocytes from OA. The inflammation model of rat OA chondrocyte model was established by using interleukin-1ß(IL-1ß) to induce. LIGc alone and combined with glycyrrhizic acid(GA), a blocker of the high mobility group box-1 protein(HMGB1)/Toll-like receptor 4(TLR4)/nuclear factor-kappa B(NF-κB) signaling pathway, were used to intervene in the model, and the therapeutic effects were systematically evaluated. The viability of chondrocytes treated with different concentrations of LIGc was measured by the cell counting kit-8(CCK-8), and the optimal LIGc concentration was screened out. Annexin V-FITC/PI apoptosis detection kit was employed to examine the apoptosis of chondrocytes in each group. The enzyme-linked immunosorbent assay(ELISA) was employed to measure the expression of cyclooxygenase-2(COX-2), prostaglandin-2(PGE2), and tumor necrosis factor-alpha(TNF-α) in the supernatant of chondrocytes in each group. Western blot was employed to determine the protein levels of B-cell lymphoma-2(Bcl-2), Bcl-2-associated X protein(Bax), caspase-3, HMGB1, TLR4, and NF-κB p65. The mRNA levels of HMGB1, TLR4, NF-κB p65, and myeloid differentiation factor 88(MyD88) in chondrocytes were determined by real-time fluorescent quantitative PCR(RT-qPCR). The safe concentration range of LIGc on chondrocytes was determined by CCK-8, and then the optimal concentration of LIGc for exerting the effect was clarified. Under the intervention of IL-1ß, the rat chondrocyte model of OA was successfully established. The modeled chondrocytes showed increased apoptosis rate, promoted expression of COX-2, PGE2, and TNF-α, up-regulated protein levels of Bax, caspase-3, HMGB1, TLR4, and NF-κB p65 and mRNA levels of HMGB1, TLR4, NF-κB p65, and MyD88, and down-regulated protein level of Bcl-2. However, LIGc reversed the IL-1ß-induced changes of the above factors. Moreover, LIGc combined with GA showed more significant reversal effect than LIGc alone. These fin-dings indicate that LIGc extracted and derived from the traditional Chinese medicine A. sinensis can inhibit the inflammatory response of chondrocytes and reduce the apoptosis of chondrocytes, and this effect may be related to the HMGB1/TLR4/NF-κB signaling pathway. The pharmacological effect of LIGc on protecting chondrocytes has potential value in delaying the progression of OA and improving the clinical symptoms of patients, and deserves further study.

Elastic parameter identification of three-dimensional soft tissue based on deep neural network.

In the field of virtual surgery and deformation simulation, the identification of elastic parameters of human soft tissues is a critical technology that directly affects the accuracy of deformation simulation. Current research on soft tissue deformation simulation predominantly assumes that the elasticity of tissues is fixed and already known, leading to the difficulty in populating with the elasticity measured or identified from specific tissues of real patients. Existing elasticity modeling efforts struggle to be implemented on irregularly structured soft tissues, failing to adapt to clinical surgical practices. Therefore, this paper proposes a new method for identifying human soft tissue elastic parameters based on the finite element method and the deep neural network, UNet. This method requires only the full-field displacement data of soft tissues under external loads to predict their elastic distribution. The performance and validity of the algorithm are assessed using test data and clinical data from rhinoplasty surgeries. Experiments demonstrate that the method proposed in this paper can achieve an accuracy of over 99% in predicting elastic parameters. Clinical data validation shows that the predicted elastic distribution can reduce the error in finite element deformation simulations by more than 80% at the maximum compared to the error with traditional uniform elastic parameters, effectively enhancing the computational accuracy in virtual surgery simulations and soft tissue deformation modeling.

Dimensional Regulation from 1D/3D to 2D/3D of Perovskite Interfaces for Stable Inverted Perovskite Solar Cells.

Constructing low-dimensional/three-dimensional (LD/3D) perovskite solar cells can improve efficiency and stability. However, the design and selection of LD perovskite capping materials are incredibly scarce for inverted perovskite solar cells (PSCs) because LD perovskite capping layers often favor hole extraction and impede electron extraction. Here, we develop a facile and effective strategy to modify the perovskite surface by passivating the surface defects and modulating surface electrical properties by incorporating morpholine hydriodide (MORI) and thiomorpholine hydriodide (SMORI) on the perovskite surface. Compared with the PI treatment that we previously developed, the one-dimensional (1D) perovskite capping layer derived from PI is transformed into a two-dimensional (2D) perovskite capping layer (with MORI or SMORI), achieving dimension regulation. It is shown that the 2D SMORI perovskite capping layer induces more robust surface passivation and stronger n-N homotype 2D/3D heterojunctions, achieving a p-i-n inverted solar cell with an efficiency of 24.55%, which retains 87.6% of its initial efficiency after 1500 h of operation at the maximum power point (MPP). Furthermore, 5 × 5 cm2 perovskite mini-modules are presented, achieving an active-area efficiency of 22.28%. In addition, the quantum well structure in the 2D perovskite capping layer increases the moisture resistance, suppresses ion migration, and improves PSCs' structural and environmental stability.

Inflammatory cytokines and their potential role in Sjogren's syndrome risk: insights from a mendelian randomization study.

AIM: This study aimed to investigate the causal impact of inflammatory cytokines on Sjogren's Syndrome (SS) and to identify potential biomarkers for SS clinical management using Mendelian Randomization (MR). MATERIALS AND METHODS: Leveraging GWAS summary data of inflammatory cytokines and SS, we executed the first two-sample MR analysis. Genetic variants from prior GWASs associated with circulating inflammatory cytokines served as instrumental variables (IVs). Data regarding cytokines were analyzed using the Olink Target-96 Inflammation panel, synthesizing data from 14,824 participants. GWAS summary statistics for SS were procured from the UK Biobank, focusing on samples of European ancestry. To discern the causal relationship between inflammatory cytokines and SS, several MR methodologies, including inverse variance weighted (IVW) and MR-Egger regression, were applied. RESULTS: After rigorous IV quality control, 91 cytokines were incorporated into the MR analysis. The IVW analysis identified 8 cytokines with a positive association to SS: Axin-1 (OR 2.56, 95% CI 1.07-6.10), T-cell surface glycoprotein CD5 (OR 1.81, 95% CI 1.08-3.02), CUDP1 (OR 1.61, 95% CI 1.00-2.58), CXCL10 (OR 1.92, 95% CI 1.25-2.95), IL-4 (OR 2.18, 95% CI 1.22-3.91), IL-7 (OR 2.35, 95% CI 1.27-4.33), MCP-2 (OR 1.27, 95% CI 1.05-1.54), and TNFRSF9 (OR 1.83, 95% CI 1.03-3.24), suggesting their potential in increasing SS risk. CONCLUSION: Our study conducted through MR, identified various inflammatory cytokines associated with SS risk, validating some previous research results and offering some new potential biomarkers for SS. However, these findings necessitate further research for validation and exploration of their precise role in the onset and progression of SS.

Exploring the potential of ChatGPT as an adjunct for generating diagnosis based on chief complaint and cone beam CT radiologic findings.

AIM: This study aimed to assess the performance of OpenAI's ChatGPT in generating diagnosis based on chief complaint and cone beam computed tomography (CBCT) radiologic findings. MATERIALS AND METHODS: 102 CBCT reports (48 with dental diseases (DD) and 54 with neoplastic/cystic diseases (N/CD)) were collected. ChatGPT was provided with chief complaint and CBCT radiologic findings. Diagnostic outputs from ChatGPT were scored based on five-point Likert scale. For diagnosis accuracy, the scoring was based on the accuracy of chief complaint related diagnosis and chief complaint unrelated diagnoses (1-5 points); for diagnosis completeness, the scoring was based on how many accurate diagnoses included in ChatGPT's output for one case (1-5 points); for text quality, the scoring was based on how many text errors included in ChatGPT's output for one case (1-5 points). For 54 N/CD cases, the consistence of the diagnosis generated by ChatGPT with pathological diagnosis was also calculated. The constitution of text errors in ChatGPT's outputs was evaluated. RESULTS: After subjective ratings by expert reviewers on a five-point Likert scale, the final score of diagnosis accuracy, diagnosis completeness and text quality of ChatGPT was 3.7, 4.5 and 4.6 for the 102 cases. For diagnostic accuracy, it performed significantly better on N/CD (3.8/5) compared to DD (3.6/5). For 54 N/CD cases, 21(38.9%) cases have first diagnosis completely consistent with pathological diagnosis. No text errors were observed in 88.7% of all the 390 text items. CONCLUSION: ChatGPT showed potential in generating radiographic diagnosis based on chief complaint and radiologic findings. However, the performance of ChatGPT varied with task complexity, necessitating professional oversight due to a certain error rate.

The role of blood metabolites in oral cancer: insights from a Mendelian randomization approach.

Aim: This research aimed to explore the causal impact of blood metabolites on oral cancer using a two-sample Mendelian randomization (MR) analysis. The study endeavored to identify potential biomarkers for oral cancer's clinical management. Materials and methods: Based on the large individual-level datasets from UK Biobank as well as GWAS summary datasets, we first constructed genetic risk scores (GRSs) of 486 human blood metabolites and evaluated the effect on oral cancer. Various statistical methods, including inverse variance weighted (IVW), MR-Egger, and weighted median, among others, were employed to analyze the potential causal relationship between blood metabolites and oral cancer. The sensitivity analyses were conducted using Cochran's Q tests, funnel plots, leave-one-out analyses, and MR-Egger intercept tests. Results: 29 metabolites met the stringent selection criteria. Out of these, 14 metabolites demonstrated a positive association with oral cancer risk, while 15 metabolites indicated a protective effect against oral cancer. The IVW-derived estimates were significant, and the results were consistent across different statistical methodologies. Both the Cochran Q test and the MR-Egger intercept test indicated no heterogeneity and pleiotropy. Conclusion: This MR study offers evidence of the role specific blood metabolites play in oral cancer, pinpointing several with potential risk or protective effects. These findings could be helpful for new diagnostic tools and treatments for oral cancer. While the results are promising, additional research is necessary to fully validate and refine these conclusions. This study serves as a foundational step towards more comprehensive understandings in the future.

Multifunctional two-dimensional perovskite based solar cells for photodetectors and resistive switching.

The escalating interest in low-dimensional perovskites stems from their tunable optoelectronic traits and robust stability. The pursuit of multifaceted optoelectronic devices holds substantial importance for energy-efficient and space-constrained systems. This investigation showcases the realization of multifunctional two-dimensional perovskite solar cells, incorporating transient light detection and resistive switching functions within a single device, achievable by facile external bias adjustments. Serving as a photodetector, the device exhibits commendable self-powered photodetection attributes, including an exceptionally low dark current density of 1 nA mm-2, a remarkable specific detectivity of 7.67 × 1012 Jones, a swift response time of 0.60 µs, and an expansive linear dynamic range of 72 dB. As a memristor, it showcases enduring performance across 4 × 102 cycles, a substantial on/off ratio of 106, and a rapid operation time of less than 1 µs. This endeavor unveils a pioneering avenue for advancing high-performance, air-stable multifunctional two-dimensional perovskite electronics.

Multifunctional dual-interface layer enables efficient and stable inverted perovskite solar cells.

Considering that the hydrophobicity of PTAA as the surface of an inverted perovskite solar cell (PSC) substrate directly influences the crystallization and top surface properties of perovskite films, dual-interface engineering is a significant strategy to obtain excellent PSCs. PFN-Br was inserted into the PTAA/perovskite interface to ensure close interfacial contact and achieve exceptional crystallization, and then the perovskite top surface was covered with 3-PyAI to further improve its interface property. The mechanism of interaction of PFN-Br and 3-PyAI with perovskites was analyzed through various characterization methods. The results showed that the introduction of a hydrophilic interface layer reduces voids and defects at the bottom of the film. Additionally, the existence of 3-PyAI reduces surface defects, optimizes energy level alignment, and decreases non-radiative recombination, which is beneficial for charge transfer. Consequently, the open circuit voltage (VOC) and fill factor (FF) of the optimized device were greatly enhanced, and the champion device showed a power conversion efficiency (PCE) of 22.07%. The unencapsulated device with PFN-Br&3-PyAI can retain 80% of its initial performance after aging in the air atmosphere (25 °C at a relative humidity (RH) of 25%) for 27 days. Moreover, the reverse bias stability of the device was improved, with the reverse breakdown voltage (VRB) reaching -2 V. This work recommends a dual-interface strategy for efficient and reliable PTAA-based PSCs.

Modulating the Dipole Moment of Secondary Ammonium Spacers for Efficient 2D Ruddlesden-Popper Perovskite Solar Cells.

Layered two-dimensional (2D) perovskites are emerging as promising optoelectronic materials owing to their excellent environmental stability. Regulating the dipole moment of organic spacers has the potential to reduce the exciton binding energy (Eb ) of 2D perovskites and improve their photovoltaic performance. Here, we developed two azetidine-based secondary ammonium spacers with different electron-withdrawing groups, namely 3-hydroxyazatidine (3-OHAz) and 3,3-difluoroazetidine (3,3-DFAz) spacers, for 2D Ruddlesden-Popper (RP) perovskites. It was found that the large dipole moment of the fluorinated dipole spacer could effectively enhance the interaction between organic spacers and inorganic layers, leading to improved charge dissociation in 2D RP perovskite. In contrast to 3-OHAz spacer, the 2D perovskite using 3,3-DFAz as spacer also shows improved film quality, optimized energy level alignment, and reduced exciton binding energy. As a result, the 2D perovskite (n=4) device based on 3,3-DFAz yields an outstanding efficiency of 19.28 %, surpassing that of the 3-OHAz-Pb device (PCE=11.35 %). The efficiency was further improved to 19.85 % when using mixed A-site cation of MA0.95 FA0.05 . This work provides an effective strategy for modulating the energy level alignment and reducing the Eb by regulating the dipole moment of organic spacers, ultimately enabling the development of high-performance 2D perovskite solar cells.

Three-dimensional nasal asymmetry analysis between adolescence and adulthood in postoperative patients with unilateral cleft lip and palate using computed tomography.

AIM: To investigate the differences of the nasal soft and hard tissue asymmetry in postoperative patients with unilateral cleft lip and palate (UCLP) between adolescence and adulthood, and to explore the correlation of nasal soft and hard tissue asymmetry. METHODS: CT data from 47 repaired UCLP patients were included and divided into two groups:1. adolescent group: 23 patients (15 males, 8 females; age: 10-12 years old). 2. adult group: 24 patients (16 males, 8 females; age:18-32 years old). The three-dimensional asymmetry in nasal soft and hard tissues was analyzed. Additionally, the correlation between nasal soft and hard tissue asymmetry was also analyzed. RESULTS: Both the adolescent group and adult group showed asymmetries in nasal soft and hard tissues. Compared to the adolescent group, the adult group had a significantly increased horizontal asymmetry of nasal soft tissues Sbal (P < 0.05). Furthermore, the sagittal asymmetry of soft tissue Glat (P < 0.05), Sbal (P < 0.001), Sni (P < 0.001) and hard tissue LPA (P < 0.05) also increased significantly. In the adult group, there were more landmarks with a correlation between the asymmetry of nasal hard tissue and soft tissue compared to the adolescent group. There were moderate to strong correlations between nasal hard and soft tissue symmetries in the horizontal and sagittal directions (0.444 < r < 764), but no correlation in the vertical direction in the adult group (P > 0.05). CONCLUSIONS: The asymmetry of nasal soft and hard tissues in patients with repaired UCLP becomes more apparent in the horizontal and sagittal dimensions from adolescence to adulthood. The correlation between the asymmetry of nasal hard tissue and soft tissue becomes stronger in the horizontal and sagittal dimensions. These factors should be taken into account when performing treatment for repaired UCLP patients in adolescence and adulthood.

Ternary-Metal Sn-Pb-Zn Perovskite to Reconstruct Top Surface for Efficient and Stable Less-Pb Perovskite Solar Cells.

Though Sn-Pb alloyed perovskite solar cells (PSCs) achieved great progress, there is a dilemma to further increase Sn for less-Pb requirement. High Sn ratio (>70%) perovskite exhibits nonstoichiometric Sn:Pb:I at film surface to aggravate Sn2+ oxidation and interface energy mismatch. Here, ternary metal alloyed (FASnI3 )0.7 (MAPb1- x Znx I3 )0.3 (x = 0-3%) is constructed for Pb% < 30% perovskite. Zn with smaller ionic size and stronger ionic interaction than Sn/Pb assists forming high-quality perovskite film with ZnI6 4- enriched at surface to balance Sn:Pb:I ratio. Differing from uniform bulk doping, surface-rich Zn with lower lying orbits pushes down the energy band of perovskite and adjusts the interface energy for efficient charge transfer. The alloyed PSC realizes efficiency of 19.4% at AM1.5 (one of the highest values reported for Pb% < 30% PSCs). Moreover, stronger bonding of Zn─I and Sn─I contributes to better durability of ternary perovskite than binary perovskite. This work highlights a novel alloy method for efficient and stable less-Pb PSCs.

Identification the Role of Grain Boundaries in Polycrystalline Photovoltaics via Advanced Atomic Force Microscope.

Atomicforce microscopy (AFM)-based scanning probing techniques, including Kelvinprobe force microscopy (KPFM) and conductive atomic force microscopy (C-AFM), have been widely applied to investigate thelocal electromagnetic, physical, or molecular characteristics of functional materials on a microscopic scale. The microscopic inhomogeneities of the electronic properties of polycrystalline photovoltaic materials can be examined by these advanced AFM techniques, which bridge the local properties of materials to overall device performance and guide the optimization of the photovoltaic devices. In this review, the critical roles of local optoelectronic heterogeneities, especially at grain interiors (GIs) and grain boundaries (GBs) of polycrystalline photovoltaic materials, including versatile polycrystalline silicon, inorganic compound materials, and emerging halide perovskites, studied by KPFM and C-AFM, are systematically identified. How the band alignment and electrical properties of GIs and GBs affect the carrier transport behavior are discussed from the respective of photovoltaic research. Further exploiting the potential of such AFM-based techniques upon a summary of their up-to-date applications in polycrystalline photovoltaic materials is beneficial to acomprehensive understanding of the design and manipulation principles of thenovel solar cells and facilitating the development of the next-generation photovoltaics and optoelectronics.

Orbital Interactions in 2D Dion-Jacobson Perovskites Using Oligothiophene-Based Semiconductor Spacers Enable Efficient Solar Cells.

2D Dion-Jacobson (DJ) perovskites have emerged as promising photovoltaic materials, but the insulating organic spacer has hindered the efficient charge transport. Herein, we successfully synthesized a terthiophene-based semiconductor spacer, namely, 3ThDMA, for 2D DJ perovskite. An interesting finding is that the energy levels of 3ThDMA extensively overlap with the inorganic components and directly contribute to the band formation of (3ThDMA)PbI4, leading to enhanced charge transport across the organic spacer layers, whereas no such orbital interactions were found in (UDA)PbI4, a DJ perovskite based on 1,11-undecanediaminum (UDA). The devices based on (3ThDMA)MAn-1PbnI3n+1 (nominal n = 5) obtained a champion efficiency of 15.25%, which is a record efficiency for 2D DJ perovskite solar cells using long-conjugated spacers (conjugated rings ≥ 3) and a 22.60% efficiency for 3ThDMA-treated 3D PSCs. Our findings provide an important insight into understanding the orbital interactions in 2D DJ perovskite using an organic semiconductor spacer for efficient solar cells.

Nucleation and Crystallization in 2D Ruddlesden-Popper Perovskites using Formamidinium-based Organic Semiconductor Spacers for Efficient Solar Cells.

The conjugated organic semiconductor spacers have drawn wide attention in two-dimensional (2D) perovskites and formamidinium (FA) has been widely used as A-site cation in high-performance 3D perovskite solar cells (PSCs). However, the FA-based semiconductor spacers have rarely been investigated in 2D Ruddlesden-Popper (RP) perovskites. Here, we developed two FA-based spacers containing thieno[3,2-b]thiophene (TT) and 2,2'-bithiophene (BT) units, namely TTFA and BTFA, respectively, for 2D RP PSCs. The nucleation and crystallization kinetics of TTFA-Pb and BTFA-Pb from sol-gel to film were investigated using in situ optical microscopy and in situ grazing incidence wide-angle X-ray scattering (GIWAXS) measurements. It is found that the TTFA spacer could reduce the energy barrier of nucleation and induces crystal vertical orientation of 2D perovskite by forming larger clusters in precursor solution, resulting in much improved film quality. Benefiting from the enlarged crystal grains, reduced exciton binding energy, and decreased electron-phonon coupling coefficient, the photovoltaic device based on (TTFA)2 MAn-1 Pbn I3n+1 (n=5) achieved a champion efficiency of 19.41 %, which is a record for 2D RP PSCs with FA-based spacers. Our work provides deep understanding of the nucleation and crystallization process of 2D RP perovskite films and highlights the great potential of FA-based semiconductor spacers in highly efficient 2D PSCs.