Revealing the impact of thermal annealing on the perovskite/organic bulk heterojunction interface in photovoltaic devices.

Perovskite/organic bulk heterojunction (BHJ) integrated solar cells have tremendous development potential to exceed the Shockley-Queisser limit efficiency of single-junction photovoltaics, due to the merits of spectra response extension. However, the presence of energy level barriers and severe non-radiative recombination at the interface between perovskite and BHJ greatly hindered the transport and collection of charge carriers, usually leading to large Voc and photocurrent loss, as well as the stability degradation of integrated devices. Therefore, investigating the interface properties of perovskite/BHJ is crucial for understanding the charge transport process and enhancing device performance. In this study, we effectively regulated the interface properties and charge transport in perovskite/BHJ integrated devices using a thermal annealing process. Using Kelvin probe microscopy, photoluminescence, and transient absorption spectroscopy, we revealed that moderate annealing treatment would contribute to forming close interface contact and provide more channels or pathways for charge transfer, which is advantageous for the interface charge collection and device performance. In addition, the lone pair electrons of acyl, thiophene and pyrrole function groups in polymer PDPP3T and PCBM can act as the Lewis base and provide electrons to the under-coordinated lead atoms or clusters in the perovskite, effectively passivating traps on the surface and grain boundaries of the perovskite through Lewis acid-base coordination. Finally, we improved the photovoltaic conversion efficiency of the device to 21.57% with enhanced stability using an optimized thermal annealing process. This study provides a comprehensive understanding of the integrated perovskite/BHJ interface properties, which could be extended to other optoelectronic devices based on a similar integrated structure.

Pan-cancer analysis implicates novel insights of lactate metabolism into immunotherapy response prediction and survival prognostication.

BACKGROUND: Immunotherapy has emerged as a potent clinical approach for cancer treatment, but only subsets of cancer patients can benefit from it. Targeting lactate metabolism (LM) in tumor cells as a method to potentiate anti-tumor immune responses represents a promising therapeutic strategy. METHODS: Public single-cell RNA-Seq (scRNA-seq) cohorts collected from patients who received immunotherapy were systematically gathered and scrutinized to delineate the association between LM and the immunotherapy response. A novel LM-related signature (LM.SIG) was formulated through an extensive examination of 40 pan-cancer scRNA-seq cohorts. Then, multiple machine learning (ML) algorithms were employed to validate the capacity of LM.SIG for immunotherapy response prediction and survival prognostication based on 8 immunotherapy transcriptomic cohorts and 30 The Cancer Genome Atlas (TCGA) pan-cancer datasets. Moreover, potential targets for immunotherapy were identified based on 17 CRISPR datasets and validated via in vivo and in vitro experiments. RESULTS: The assessment of LM was confirmed to possess a substantial relationship with immunotherapy resistance in 2 immunotherapy scRNA-seq cohorts. Based on large-scale pan-cancer data, there exists a notably adverse correlation between LM.SIG and anti-tumor immunity as well as imbalance infiltration of immune cells, whereas a positive association was observed between LM.SIG and pro-tumorigenic signaling. Utilizing this signature, the ML model predicted immunotherapy response and prognosis with an AUC of 0.73/0.80 in validation sets and 0.70/0.87 in testing sets respectively. Notably, LM.SIG exhibited superior predictive performance across various cancers compared to published signatures. Subsequently, CRISPR screening identified LDHA as a pan-cancer biomarker for estimating immunotherapy response and survival probability which was further validated using immunohistochemistry (IHC) and spatial transcriptomics (ST) datasets. Furthermore, experiments demonstrated that LDHA deficiency in pancreatic cancer elevated the CD8+ T cell antitumor immunity and improved macrophage antitumoral polarization, which in turn enhanced the efficacy of immunotherapy. CONCLUSIONS: We unveiled the tight correlation between LM and resistance to immunotherapy and further established the pan-cancer LM.SIG, holds the potential to emerge as a competitive instrument for the selection of patients suitable for immunotherapy.

BHLHE40 Inhibits Ferroptosis in Pancreatic Cancer Cells via Upregulating SREBF1.

Pancreatic cancer (PCa) is one of the most fatal human malignancies. The enhanced infiltration of stromal tissue into the PCa tumor microenvironment limits the identification of key tumor-specific transcription factors and epigenomic abnormalities in malignant epithelial cells. Integrated transcriptome and epigenetic multiomics analyses of the paired PCa organoids indicate that the basic helix-loop-helix transcription factor 40 (BHLHE40) is significantly upregulated in tumor samples. Increased chromatin accessibility at the promoter region and enhanced mTOR pathway activity contribute to the elevated expression of BHLHE40. Integrated analysis of chromatin immunoprecipitation-seq, RNA-seq, and high-throughput chromosome conformation capture data, together with chromosome conformation capture assays, indicate that BHLHE40 not only regulates sterol regulatory element-binding factor 1 (SREBF1) transcription as a classic transcription factor but also links the enhancer and promoter regions of SREBF1. It is found that the BHLHE40-SREBF1-stearoyl-CoA desaturase axis protects PCa cells from ferroptosis, resulting in the reduced accumulation of lipid peroxidation. Moreover, fatostatin, an SREBF1 inhibitor, significantly suppresses the growth of PCa tumors with high expressions of BHLHE40. This study highlights the important roles of BHLHE40-mediated lipid peroxidation in inducing ferroptosis in PCa cells and provides a novel mechanism underlying SREBF1 overexpression in PCa.

SNHG17 alters anaerobic glycolysis by resetting phosphorylation modification of PGK1 to foster pro-tumor macrophage formation in pancreatic ductal adenocarcinoma.

BACKGROUND: Within the tumor immune microenvironment (TME), tumor-associated macrophages (TAMs) are crucial in modulating polarization states to influence cancer development through metabolic reprogramming. While long non-coding RNAs (lncRNAs) have been shown to play a pivotal role in the progression of various cancers, the underlying mechanisms by which lncRNAs alter M2 polarization through macrophage metabolism remodeling remain unelucidated. METHODS: RNA sequencing was used to screen for differentially expressed lncRNAs in TAMs and normal tissue-resident macrophages (NTRMs) isolated from pancreatic ductal adenocarcinoma (PDAC) tissues, whilst RT-qPCR and FISH were employed to detect the expression level of SNHG17. Moreover, a series of in vivo and in vitro experiments were conducted to assess the functions of SNHG17 from TAMs in the polarization and glycolysis of M2-like macrophages and in the proliferation and metastasis of pancreatic cancer cells (PCs). Furthermore, Western blotting, RNA pull-down, mass spectrometry, RIP, and dual-luciferase assays were utilized to explore the underlying mechanism through which SNHG17 induces pro-tumor macrophage formation. RESULTS: SNHG17 was substantially enriched in TAMs and was positively correlated with a worse prognosis in PDAC. Meanwhile, functional assays determined that SNHG17 promoted the malignant progression of PCs by enhancing M2 macrophage polarization and anaerobic glycolysis. Mechanistically, SNHG17 could sponge miR-628-5p to release PGK1 mRNA and concurrently interact with the PGK1 protein, activating the pro-tumorigenic function of PGK1 by enhancing phosphorylation at the T168A site of PGK1 through ERK1/2 recruitment. Lastly, SNHG17 knockdown could reverse the polarization status of macrophages in PDAC. CONCLUSIONS: The present study illustrated the essential role of SNHG17 and its molecular mechanism in TAMs derived from PDAC, indicating that SNHG17 might be a viable target for PDAC immunotherapy.

ATF3-induced activation of NF-κB pathway results in acquired PARP inhibitor resistance in pancreatic adenocarcinoma.

PURPOSE: Olaparib, an inhibitor of poly-(adenosine diphosphate-ribose) polymerase (PARP), has been shown to have anticancer benefits in patients with pancreatic cancer who have a germline mutation in BRCA1/2. However, resistance acquired on long-term exposure to olaparib significantly impedes clinical efficacy. METHODS: In this study, the chromatin accessibility and differentially expressed transcripts of parental and olaparib-resistant pancreatic cancer cell lines were assessed using the Assay for Transposase Accessible Chromatin with sequencing (ATAC-seq) and mRNA-seq. Detection of downstream genes regulated by transcription factors using ChIP (Chromatin immunoprecipitation assay). RESULTS: According to pathway enrichment analysis, differentially expressed genes in olaparib-resistant cells were remarkably enriched in the NF-κB signaling pathway. With ATAC-seq, we identified chromatin regions with higher accessibility in olaparib-resistant cells and predicted a series of important transcription factors. Among them, activating transcription factor 3 (ATF3) was significantly highly expressed. Functional experiments verified that inhibition of ATF3 suppressed the NF-κB pathway significantly and restored olaparib sensitivity in olaparib-resistant cells. CONCLUSION: Experiments in vitro and in vivo indicate ATF3 enhances olaparib resistance through the NF-κB signaling pathway, suggesting that ATF3 could be employed as an olaparib sensitivity and prognostic indicator in patients with pancreatic cancer.

A microprotein N1DARP encoded by LINC00261 promotes Notch1 intracellular domain (N1ICD) degradation via disrupting USP10-N1ICD interaction to inhibit chemoresistance in Notch1-hyperactivated pancreatic cancer.

The extensively activated Notch signaling pathway in pancreatic cancer cells is important in carcinogenesis, chemoresistance, and recurrence. Targeting this pathway is a promising therapeutic strategy for pancreatic cancer; however, few successful approaches have been reported, and currently used molecular inhibitors of this pathway exhibit limited clinical benefits. In this study, we identified a previously uncharacterized microprotein, Notch1 degradation-associated regulatory polypeptide (N1DARP), encoded by LINC00261. N1DARP knockout accelerated tumor progression and enhanced stem cell properties in pancreatic cancer organoids and LSL-Kras, LSL-Trp53, and Pdx1-Cre (KPC) mice. Mechanistically, N1DARP suppressed canonical and non-canonical Notch1 pathways by competitively disrupting the interaction between N1ICD and ubiquitin-specific peptidase 10 (USP10), thereby promoting K11- and K48-linked polyubiquitination of N1ICD. To evaluate the therapeutic potential of N1DARP, we designed a cell-penetrating stapled peptide, SAH-mAH2-5, with a helical structure similar to that of N1DARP that confers remarkable physicochemical stability. SAH-mAH2-5 interacted with and promoted the proteasome-mediated degradation of N1ICD. SAH-mAH2-5 injection provided substantial therapeutic benefits with limited off-target and systemic adverse effects in Notch1-activated pancreatic cancer models. Taken together, these findings confirm that N1DARP acts as a tumor suppressor and chemosensitizer by regulating USP10-Notch1 oncogenic signaling, and suggest a promising therapeutic strategy targeting the N1DARP-N1ICD interaction in Notch1-activated pancreatic cancer.

Remarkable Stability and Optoelectronic Properties of an All-Inorganic CsSn0.5Ge0.5I3 Perovskite Solar Cell.

Sn-Ge mixed perovskites have been proposed as promising lead-free candidates in the photovoltaics (PV) field. In this work, we discovered a stable P1 phase Sn-Ge mixed structure (CsSn0.5Ge0.5I3) with an appropriate band gap value of 1.19 eV, which manifests its unique structural stability and physics properties. The thermodynamic stability of this mixed structure under different growth conditions and all possible native defects are depicted in detail. The formation energies and dominant native point defects indicate that P1 phase CsSn0.5Ge0.5I3 exhibits unipolar self-doping behavior (p-type conductivity) and good defect tolerance while the growth condition changes. In addition, the calculation of light absorption confirmed that the P1 phase has a higher light absorption coefficient than that of MAPbI3 in the visible light range, showing excellent light absorption. Our work not only provides theoretical guidance for unraveling the unusual structural stability of Sn-Ge mixed perovskites, but also offers a useful scheme to modulate the stability and optoelectronic properties of Ge-based perovskites through alloy engineering.

Fast, Multi-Bit, and Vis-Infrared Broadband Nonvolatile Optoelectronic Memory with MoS2 /2D-Perovskite Van der Waals Heterojunction.

Nonvolatile optoelectronic memory (NVOM) integrating the functions of optical sensing and long-term memory can efficiently process and store a large amount of visual scene information, which has become the core requirement of multiple intelligence scenarios. However, realizing NVOM with vis-infrared broadband response is still challenging. Herein, the room temperature vis-infrared broadband NVOM based on few-layer MoS2 /2D Ruddlesden-Popper perovskite (2D-RPP) van der Waals heterojunction is realized. It is found that the 2D-RPP converts the initial n-type MoS2 into p-type and facilitates hole transfer between them. Furthermore, the 2D-RPP rich in interband states serves as an effective electron trapping layer as well as broadband photoresponsive layer. As a result, the dielectric-free MoS2 /2D-RPP heterojunction enables the charge to transfer quickly under external field, which enables a large memory window (104 V), fast write speed of 20 µs, and optical programmable characteristics from visible light (405 nm) to telecommunication wavelengths (i.e., 1550 nm) at room temperature. Trapezoidal optical programming can produce up to 100 recognizable states (>6 bits), with operating energy as low as 5.1 pJ per optical program. These results provide a route to realize fast, low power, multi-bit optoelectronic memory from visible to the infrared wavelength.

Single-cell RNA-seq analysis reveals BHLHE40-driven pro-tumour neutrophils with hyperactivated glycolysis in pancreatic tumour microenvironment.

OBJECTIVE: Innate immunity plays important roles in pancreatic ductal adenocarcinoma (PDAC), as non-T-cell-enriched tumour. Neutrophils are major players in innate immune system. Here, we aimed to explore the heterogeneity and pro-tumour mechanisms of neutrophils in PDAC. DESIGN: We analysed single-cell transcriptomes of peripheral blood polymorphonuclear leucocytes (PMNs) and tumour-infiltrating immune cells from five patients with PDAC, and performed immunofluorescence/immunohistochemistry staining, multi-omics analysis and in vitro experiments to validate the discoveries of bioinformatics analysis. RESULTS: Exploration of the heterogeneity of tumour-associated neutrophils (TANs) revealed a terminally differentiated pro-tumour subpopulation (TAN-1) associated with poor prognosis, an inflammatory subpopulation (TAN-2), a population of transitional stage that have just migrated to tumour microenvironment (TAN-3) and a subpopulation preferentially expressing interferon-stimulated genes (TAN-4). Glycolysis signature was upregulated along neutrophil transition trajectory, and TAN-1 was featured with hyperactivated glycolytic activity. The glycolytic switch of TANs was validated by integrative multi-omics approach of transcriptomics, proteomics and metabolomics analysis. Activation of glycolytic activity by LDHA overexpression induced immunosuppression and pro-tumour functions in neutrophil-like differentiated HL-60 (dHL-60) cells. Mechanistic studies revealed BHLHE40, downstream to hypoxia and endoplasmic reticulum stress, was a key regulator in polarisation of neutrophils towards TAN-1 phenotype, and direct transcriptional regulation of BHLHE40 on TAN-1 marker genes was demonstrated by chromatin immunoprecipitation assay. Pro-tumour and immunosuppression functions were observed in dHL-60 cells overexpressing BHLHE40. Importantly, immunohistochemistry analysis of PDAC tissues revealed the unfavourable prognostic value of BHLHE40+ neutrophils. CONCLUSION: The dynamic properties of TANs revealed by this study will be helpful in advancing PDAC therapy targeting innate immunity.

A Perovskite Photodetector Crossbar Array by Vapor Deposition for Dynamic Imaging.

With the development of perovskite photodetectors, integrating photodetectors into array image sensors is the next target to pursue. The major obstacle to integrating perovskite photodiodes for dynamic imaging is the optoelectrical crosstalk among the pixels. Herein, a perovskite photodiode-blocking diode (PIN-BD) crossbar array with pixel-wise rectifying property by the vapor deposition method is presented. The PIN-BD shows a large rectification ratio of 3.3 × 102 under illumination, suppressing electrical crosstalk to as small as 8.0% in the imaging array. The fast response time of 72.8 ns allows real-time image acquisition by over 25 frames per second. The imaging sensor exhibits excellent imaging capability with a large linear dynamic range of 112 dB with 4096 gray levels and weak light sensitivity under 1.2 lux.

High-κ van der Waals Oxide MoO3 as Efficient Gate Dielectric for MoS2 Field-Effect Transistors.

Two-dimensional van der Waals crystals (2D vdW) are recognized as one of the potential materials to solve the physical limits caused by size scaling. Here, vdW metal oxide MoO3 is applied with the gate dielectric in a 2D field-effect transistor (FET). Due to its high dielectric constant and the good response of MoS2 to visible light, we obtained a field effect transistor for photodetection. In general, the device exhibits a threshold voltage near 0 V, Ion/Ioff ratio of 105, electron mobility about 85 cm2 V-1 s-1 and a good response to visible light, the responsivity is near 5 A/W at low laser power, which shows that MoO3 is a potential material as gate dielectric.

A new multivariate t distribution with variant tail weights and its application in robust regression analysis.

In this paper, we propose a new kind of multivariate t distribution by allowing different degrees of freedom for each univariate component. Compared with the classical multivariate t distribution, it is more flexible in the model specification that can be used to deal with the variant amounts of tail weights on marginals in multivariate data modeling. In particular, it could include components following the multivariate normal distribution, and it contains the product of independent t-distributions as a special case. Subsequently, it is extended to the regression model as the joint distribution of the error terms. Important distributional properties are explored and useful statistical methods are developed. The flexibility of the specified structure in better capturing the characteristic of data is exemplified by both simulation studies and real data analyses.

Optoelectronic Properties of α-MoO3 Tuned by H Dopant in Different Concentration.

The optoelectronic properties of layered α-MoO3 are greatly limited due to its wide band gap and low carrier concentration. The insertion of hydrogen (H) can effectively tune the band structure and carrier concentration of MoO3. Herein, first-principles calculations were performed to unravel the physical mechanism of a H-doped α-MoO3 system. We found that the modulation of the electronic structure of H-doped MoO3 depends on the doping concentration and position of the H atoms. It was found that the band gap decreases at 8% doping concentration due to the strong coupling between Mo-4d and O-2p orbits when H atoms are inserted into the interlayer. More interestingly, the band gap decreases to an extreme due to the Mo-4d orbit when all the H atoms are inserted into the intralayer only, which has a remarkable effect on light absorption. Our research provides a comprehensive theoretical discussion on the mechanism of H-doped α-MoO3 from the doping positions and doping concentrations, and offers useful strategies on doping modulation of the photoelectric properties of layered transition metal oxides.

LncRNA-PACERR induces pro-tumour macrophages via interacting with miR-671-3p and m6A-reader IGF2BP2 in pancreatic ductal adenocarcinoma.

BACKGROUND: LncRNA-PACERR plays critical role in the polarization of tissue-associated macrophages (TAMs). In this study, we found the function and molecular mechanism of PACERR in TAMs to regulate pancreatic ductal adenocarcinoma (PDAC) progression. METHODS: We used qPCR to analyse the expression of PACERR in TAMs and M1-tissue-resident macrophages (M1-NTRMs) which were isolated from 46 PDAC tissues. The function of PACERR on macrophages polarization and PDAC proliferation, migration and invasion were confirmed through in vivo and in vitro assays. The molecular mechanism of PACERR was discussed via fluorescence in situ hybridization (FISH), RNA pull-down, ChIP-qPCR, RIP-qPCR and luciferase assays. RESULTS: LncRNA-PACERR was high expression in TAMs and associated with poor prognosis in PDAC patients. Our finding validated that LncRNA-PACERR increased the number of M2-polarized cells and facilized cell proliferation, invasion and migration in vitro and in vivo. Mechanistically, LncRNA-PACERR activate KLF12/p-AKT/c-myc pathway by binding to miR-671-3p. And LncRNA-PACERR which bound to IGF2BP2 acts as an m6A-dependent manner to enhance the stability of KLF12 and c-myc in cytoplasm. In addition, the promoter of LncRNA-PACERR was a target of KLF12 and LncRNA-PACERR recruited EP300 to increase the acetylation of histone by interacting with KLF12 in nucleus. CONCLUSIONS: This study found that LncRNA-PACERR functions as key regulator of TAMs in PDAC microenvironment and revealed the novel mechanisms in cytoplasm and in nucleus.

Photoinduced Multi-Bit Nonvolatile Memory Based on a van der Waals Heterostructure with a 2D-Perovskite Floating Gate.

The development of floating-gate nonvolatile memory (FGNVM) is limited by the charge storage, retention and transfer ability of the charge-trapping layer. Here, it is demonstrated that due to the unique alternate inorganic/organic chain structure and superior optical sensitivity, an insulating 2D Ruddlesden-Popper perovskite (2D-RPP) layer can function both as an excellent charge-storage layer and a photosensitive layer. Optoelectronic memory composed of a MoS2 /hBN/2D-RPP (MBR) van der Waals heterostructure is demonstrated. The MBR device exhibits unique light-controlled charge-storage characteristics, with maximum memory window up to 92 V, high on/off ratio of 104 , negligible degeneration over 103  s, >1000 program/erase cycles, and write speed of 500 µs. Dependent on the initial states, the MBR optoelectronic memory can be programmed in both positive photoconductivity (PPC) and negative photoconductivity (NPC) modes, with up to 11 and 22 distinct resistance states, respectively. The optical program power for each bit is as low as 36/10 pJ for PPC/NPC. The results not only reveal the potential of 2D-RPP as a superior charge-storage medium in floating-gate memory, but also provides an effective strategy toward fast, low-power and stable optical multi-bit storage and neuromorphic computing.

Van der Waals MoS2/Two-Dimensional Perovskite Heterostructure for Sensitive and Ultrafast Sub-Band-Gap Photodetection.

Two-dimensional (2D) hybrid perovskites have been extensively studied as the promising light-sensitive materials in the photodetectors owing to their improved structural stability over that of their three-dimensional counterparts. However, the application of the 2D perovskite-based photodetector in the near-infrared (NIR) region is obstructed by the large intrinsic optical band gap. Herein, we develop a novel van der Waals heterostructure composed of few-layer 2D perovskite/MoS2 nanoflakes, which exhibits high-sensitivity detection performance over a broad spectral region, from the visible region to the telecommunication wavelength (i.e., 1550 nm). In particular, the photoresponsivity and specific detectivity under an 860 nm laser reach 121 A W-1 and 4.3 × 1014 Jones, respectively, whereas the individual nanoflakes show no response under the same wavelength. Meanwhile, the response time at the microsecond (µs) level is obtained, shortened by around 3 orders of magnitude compared to that of the constituting layers. The sensitive and ultrafast photoresponse at the NIR wavelength stems from the strong interlayer transition of sub-band-gap photons and the rapid separation of the photogenerated carriers by the built-in field within the heterojunction area. Our results not only provide an effective approach to achieve sub-band-gap photodetection in 2D perovskite-based structures but also suggest a universal strategy to fabricate high-performance optoelectronic devices.

Construction of Schottky contact by modification with Pt particles to enhance the performance of ultra-long V2O5 nanobelt photodetectors.

Schottky-contacted nanosensors have attracted extensive attention due to their high sensitivity and fast response time. In this article, we proved that the construction of Schottky contact by Pt nanoparticles (NPs) decoration can effectively improve the performance of V2O5 nanobelts photodetectors. After modified by Pt NPs, the photocurrent of V2O5 nanobelts is increased by more than two orders of magnitude, and the photoresponse speed is improved by at least three orders of magnitude. Detailed studies have shown that the performance enhancement is attributed to the formation of the Schottky contact at the electrode-semiconductor interface due to the decrease of surface gas adsorption and the increase of V2O5 work function after Pt NPs modification. The strong built-in field in the Schottky barrier region will quickly separate photogenerated carriers, thereby reducing the electron-hole recombination rate, resulting in the fast response time and an increase in the free carrier density. Moreover, it is found that this enhancement effect can be regulated by controlling the pressure to modulating the Schottky barrier height at the interface. Overall, the Pt NPs-modified V2O5 nanobelts photodetector exhibits a broad response spectrum (visible to near infrared), fast rise/fall response time (less than 6.12/6.15 ms), high responsivity (5.6 A/W), and high specific detectivity (6.9 × 108 Jones). This study demonstrates the feasibility of building a Schottky barrier to enhance the photodetection performance, which provides a general and effective strategy towards the construction and its practical application of supersensitive and fast-response nanosensors.

Highly Sensitive and Ultra-Broadband VO2(B) Photodetector Dominated by Bolometric Effect.

In this study, Wadsley B phase vanadium oxide (VO2(B)) with broad-band photoabsorption ability, a large temperature coefficient of resistance (TCR), and low noise was developed for uncooled broad-band detection. By using a freestanding structure and reducing the size of active area, the VO2(B) photodetector shows stable and excellent performances in the visible to the terahertz region (405 nm to 0.88 mm), with a peak TCR of -4.77% K-1 at 40 °C, a peak specific detectivity of 6.02 × 109 Jones, and a photoresponse time of 83 ms. A terahertz imaging ability with 30 × 30 pixels was demonstrated. Scanning photocurrent imaging and real-time temperature-photocurrent measurements confirm that a photothermal-type bolometric effect is the dominating mechanism. The study shows the potential of VO2(B) in applications as a new type of uncooled broad-band photodetection material and the potential to further raise the performance of broad-band photodetectors by structural design.

Plasma Oxidized Ti3C2Tx MXene as Electron Transport Layer for Efficient Perovskite Solar Cells.

Recently, the two-dimensional material Ti3C2Tx MXene has attracted interest from researchers in perovskite solar cells (PSCs) with its great advantages in terms of high transmittance, high conductivity, tunable work function, and solution processability. However, the MXene-based PSC performance has still been inferior to that of the traditional TiO2- or SnO2-based counterpart up until now. Some critical issues regarding to the MXene/perovskite interface still have not been well addressed. Herein, we used the Ti3C2Tx MXene as electron transport layer in PSCs via a room-temperature solution process followed by oxygen plasma treatment. Various characterization techniques were taken to establish the correlation between the surface properties and termination groups of MXene. We showed that oxygen plasma treatment could break parts of Ti-C bonds and generate abundant Ti-O bonds randomly distributed on MXene. The surface modification resulted in tunable work functions of MXene, as well as reduced trap states and improved electron transport close to the interface. In addition, the surface tension of MXene and corresponding perovskite morphology were thoroughly investigated by the contact angle and topography measurements. High-resolution XPS spectra indicated the Pb-O interactions between perovskite and MXene, which contributed to the device stability improvement.

Construction of an Iodine Diffusion Barrier Using Network Structure Silicone Resin for Stable Perovskite Solar Cells.

Long-term stability of organic-inorganic hybrid perovskite solar cells (PSCs) is inhibited by ion diffusion. Herein, we introduce a thermally stable and hydrophobic silicone resin layer with a network structure as an interfacial layer between the perovskite and the hole-transporting layer (HTL). Experimental and theoretical investigations confirm that the small Si-O-Si unit in the network forms both Si-I and Pb-O bonds with the perovskite surface, which physically and chemically inhibit the diffusion and self-release of iodine. Besides, the silicone resin layer suppresses the thermal crystallization of spiro-OMeTAD and optimizes the interfacial energy level alignment for hole extraction. The power conversion efficiency (PCE) of a perovskite solar cell with a silicone resin layer is improved to 21.11%. The device maintains more than 90.1% of its original PCE after 1200 h under 85 °C thermal stress, 99.6% after 2000 h under RH ∼55 ± 5%, and 83% of its original PCE after light soaking in air for 1037 h.