Synchrotron Radiation-Based In Situ GIWAXS for Metal Halide Perovskite Solution Spin-Coating Fabrication.

Solution-processable perovskite-based devices are potentially very interesting because of their relatively cheap fabrication cost but outstanding optoelectronic performance. However, the solution spin-coating process involves complicated processes, including perovskite solution droplets, nucleation of perovskite, and formation of intermediate perovskite films, resulting in complicated crystallization pathways for perovskite films under annealing. Understanding and therefore controlling the fabrication process of perovskites is difficult. Recently, synchrotron radiation-based in situ grazing-incidence wide-angle X-ray scattering (GIWAXS) techniques, which possess the advantages of high collimation, high resolution, and high brightness, have enabled to bridge complicated perovskite structure information with device performance by revealing the real-time crystallization pathways of perovskites during the spin-coating process. Herein, the developments of synchrotron radiation-based in situ GIWAXS are discussed in the study of the crystallization process of perovskites, especially revealing the important crystallization mechanisms of state-of-the-art perovskite optoelectronic devices with high performance. At the end, several potential applications and challenges associated with in situ GIWAXS techniques for perovskite-based devices are highlighted.

iso-BAI Guided Surface Recrystallization for Over 14% Tin Halide Perovskite Solar Cells.

Tin-based perovskite solar cells (PSCs) are promising environmentally friendly alternatives to their lead-based counterparts, yet they currently suffer from much lower device performance. Due to variations in the chemical properties of lead (II) and tin (II) ions, similar treatments may yield distinct effects resulting from differences in underlying mechanisms. In this work, a surface treatment on tin-based perovskite is conducted with a commonly employed ligand, iso-butylammonium iodide (iso-BAI). Unlike the passivation effects previously observed in lead-based perovskites, such treatment leads to the recrystallization of the surface, driven by the higher solubility of tin-based perovskite in common solvents. By carefully designing the solvent composition, the perovskite surface is effectively modified while preserving the integrity of the bulk. The treatment led to enhanced surface crystallinity, reduced surface strain and defects, and improved charge transport. Consequently, the best-performing power conversion efficiency of FASnI3 PSCs increases from 11.8% to 14.2%. This work not only distinguishes the mechanism of surface treatments in tin-based perovskites from that of lead-based counterparts, but also underscores the critical role in designing tailor-made strategies for fabricating efficient tin-based PSCs.

Over-18%-Efficiency Quasi-2D Ruddlesden-Popper Pb-Sn Mixed Perovskite Solar Cells by Compositional Engineering.

Quasi-two-dimensional (2D) Pb-Sn mixed perovskites show great potential in applications of single and tandem photovoltaic devices, but they suffer from low efficiencies due to the existence of horizontal 2D phases. Here, we obtain a record high efficiency of 18.06% based on 2D ⟨n⟩ = 5 Pb-Sn mixed perovskites (iso-BA2MA4(PbxSn1-x)5I16, x = 0.7), by optimizing the crystal orientation through a regulation of the Pb/Sn ratio. We find that Sn-rich precursors give rise to a mixture of horizontal and vertical 2D phases. Interestingly, increasing the Pb content can not only entirely suppress the unwanted horizontal 2D phase in the film but also enhance the growth of vertical 2D phases, thus significantly improving the device performance and stability. It is suggested that an increase of the Pb content in the Pb-Sn mixed systems facilitates the incorporation of iso-butylammonium (iso-BA+) ligands in vertically oriented perovskites because of the reduced lattice strain and increased interaction between the organic ligands and inorganic framework. Our work sheds light on the optimal conditions for fabricating stable and efficient 2D Pb-Sn mixed perovskite solar cells.

Controllable Black-to-Yellow Phase Transition by Tuning the Lattice Symmetry in Perovskite Quantum Dots.

The black-to-yellow phase transition in perovskite quantum dots (QDs) is more complex than in bulk perovskites, regarding the role of surface energy. Here, with the assistance of in situ grazing-incidence wide-angle and small-angle X-ray scattering (GIWAXS/GISAXS), distinct phase behaviors of cesium lead iodide (CsPbI3 ) QD films under two different temperature profiles-instant heating-up (IHU) and slow heating-up (SHU) is investigated. The IHU process can cause the phase transition from black phase to yellow phase, while under the SHU process, the majority remains in black phase. Detailed studies and structural refinement analysis reveal that the phase transition is triggered by the removal of surface ligands, which switches the energy landscape. The lattice symmetry determines the transition rate and the coexistence black-to-yellow phase ratio. The SHU process allows longer relaxation time for a more ordered QD packing, which helps sustain the lattice symmetry and stabilizes the black phase. Therefore, one can use the lattice symmetry as a general index to monitor the CsPbI3 QD phase transition and finetune the coexistence black-to-yellow phase ratio for niche applications.

MiR-183-5p promotes migration and invasion of prostate cancer by targeting TET1.

BACKGROUND: Prostate cancer (PCa) is one of the common malignant tumors worldwide. MiR-183-5p has been reported involved in the initiation of human PCa, this study aimed to investigate whether miR-183-5p affects the development of prostate cancer. METHODS: In this study, we analyzed the expression of miR-183-5p in PCa patients and its correlation with clinicopathological parameters based on TCGA data portal. CCK-8, migration assay and invasion and wound-healing assay were performed to detect proliferation, migration and invasion in PCa cells. RESULTS: We found the expression of miR-183-5p was significantly increased in PCa tissues, and high expression of miR-183 was positively associated with poor prognosis of PCa patients. Over-expression of miR-183-5p promoted the migration, invasion capacities of PCa cells, whereas knockdown of miR-183-5p showed reversed function. Furthermore, luciferase reporter assay showed TET1 was identified as a direct target of miR-183-5p, which was negatively correlation with miR-183-5p expression level. Importantly, rescue experiments demonstrated TET1 over-expression could reverse miR-183-5p mimic induced-acceleration of PCa malignant progression. CONCLUSION: Our results indicated that miR-183-5p could act as a tumor promoter in PCa and it accelerated the malignant progression of PCa by directly targeting and down-regulating TET1.

Self-Generated Buried Submicrocavities for High-Performance Near-Infrared Perovskite Light-Emitting Diode.

Embedding submicrocavities is an effective approach to improve the light out-coupling efficiency (LOCE) for planar perovskite light-emitting diodes (PeLEDs). In this work, we employ phenethylammonium iodide (PEAI) to trigger the Ostwald ripening for the downward recrystallization of perovskite, resulting in spontaneous formation of buried submicrocavities as light output coupler. The simulation suggests the buried submicrocavities can improve the LOCE from 26.8 to 36.2% for near-infrared light. Therefore, PeLED yields peak external quantum efficiency (EQE) increasing from 17.3% at current density of 114 mA cm-2 to 25.5% at current density of 109 mA cm-2 and a radiance increasing from 109 to 487 W sr-1 m-2 with low rolling-off. The turn-on voltage decreased from 1.25 to 1.15 V at 0.1 W sr-1 m-2. Besides, downward recrystallization process slightly reduces the trap density from 8.90 × 1015 to 7.27 × 1015 cm-3. This work provides a self-assembly method to integrate buried output coupler for boosting the performance of PeLEDs.

High-Efficiency Low-Lead Perovskite Photovoltaics Approaching 20% Enabled by a Vacuum-Drying Strategy.

Lead-tin mixed perovskites are excellent photovoltaic materials that can be used in single- or multi-junction perovskite solar cells (PSCs). However, most high-performance Pb-Sn mixed PSCs reported to date are still Pb-dominant. It is highly demanding to develop environmentally friendly low-lead PSCs, but the poor film quality caused by the uncontrollable crystallization kinetics has been hindering the efficiency improvement of low-lead PSCs. Here, a vacuum-drying strategy in the two-step method to fabricate low-lead PSCs (FAPb0.3 Sn0.7 I3 ) with an impressive efficiency of 19.67% is employed. The vacuum treatment induces the formation of low crystalline Pb0.3 Sn0.7 I2 films containing less solvent, thus facilitating the subsequent FAI penetration and suppressing pinholes. Compared with the conventional one-step method, the two-step fabricated low-lead perovskite films with the vacuum-drying treatment exhibit a larger grain size, lower trap density, and weaker recombination loss, thus giving rise to a record-high efficiency near 20% with better thermal stability.

How Do Surface Polar Molecules Contribute to High Open-Circuit Voltage in Perovskite Solar Cells?

To date, the improvement of open-circuit voltage (VOC ) offers a breakthrough for the performance of perovskite solar cells (PSCs) toward their theoretical limit. Surface modification through organic ammonium halide salts (e.g., phenethylammonium ions PEA+ and phenmethylammonium ions PMA+ ) is one of the most straightforward strategies to suppress defect density, thereby leading to improved VOC . However, the mechanism underlying the high voltage remains unclear. Here, polar molecular PMA+ is applied at the interface between perovskite and hole transporting layer and a remarkably high VOC of 1.175 V is obtained which corresponds to an increase of over 100 mV in comparison to the control device. It is revealed that the equivalent passivation effect of surface dipole effectively improves the splitting of the hole quasi-Fermi level. Ultimately the combined effect of defect suppression and surface dipole equivalent passivation effect leads to an overall increase in significantly enhanced VOC . The resulted PSCs device reaches an efficiency of up to 24.10%. Contributions are identified here by the surface polar molecules to the high VOC in PSCs. A fundamental mechanism is suggested by use of polar molecules which enables further high voltage, leading ways to highly efficient perovskite-based solar cells.

A Bifunctional Carbazide Additive For Durable CsSnI3 Perovskite Solar Cells.

Inorganic CsSnI3 with low toxicity and a narrow bandgap is a promising photovoltaic material. However, the performance of CsSnI3 perovskite solar cells (PSCs) is much lower than that of Pb-based and hybrid Sn-based (e.g., CsPbX3 and CH(NH2 )2 SnX3 ) PSCs, which may be attributed to its poor film-forming property and the deep traps induced by Sn4+ . Here, a bifunctional additive carbazide (CBZ) is adapted to deposit a pinhole-free film and remove the deep traps via two-step annealing. The lone electrons of the NH2 and CO units in CBZ can coordinate with Sn2+ to form a dense film with large grains during the phase transition at 80 °C. The decomposition of CBZ can reduce Sn4+ to Sn2+ during annealing at 150 °C to remove the deep traps. Compared with the control device (4.12%), the maximum efficiency of the CsSnI3 :CBZ PSC reaches 11.21%, which is the highest efficiency of CsSnI3 PSC reported to date. A certified efficiency of 10.90% is obtained by an independent photovoltaic testing laboratory. In addition, the unsealed CsSnI3 :CBZ devices maintain initial efficiencies of ≈100%, 90%, and 80% under an inert atmosphere (60 days), standard maximum power point tracking (650 h at 65 °C), and ambient air (100 h), respectively.

Manipulating Crystallographic Orientation via Cross-Linkable Ligand for Efficient and Stable Perovskite Solar Cells.

The crystallographic orientation of polycrystalline perovskites is found to be strongly correlated with their intrinsic properties; therefore, it can be used to effectively enhance the performance of perovskite-based devices. Here, a facile way of manipulating the facet orientation of polycrystalline perovskite films in a controllable manner is reported. By incorporating a cross-linkable organic ligand into the perovskite precursor solution, the crystal orientation disorder can be reduced in the resultant perovskite films to exhibit the prominent (001) orientation with a preferred stacking mode. Moreover, the as-formed low-dimensional perovskites (LDPs) between the organic ligand and the excess lead iodide can passivate the defects around the grain boundaries. Consequently, highly efficient p-i-n structured perovskite solar cells (PSCs) can be made in both rigid and flexible forms from modified perovskites to show high power conversion efficiencies (PCE) of 24.12% and 23.23%, respectively. The devices also exhibit superior long-term stability in a humid environment (with T90  > 1000 h) and under thermal stress (retaining 87% of its initial PCE after 1000 h). More importantly, the ligand enables the derived LDPs to be crosslinked (under 254 nm UV illumination) to demonstrate excellent mechanical bending durability in flexible devices.

Critical Influence of Organic A'-Site Ligand Structure on 2D Perovskite Crystallization.

Organic A'-site ligand structure plays a crucial role in the crystal growth of 2D perovskites, but the underlying mechanism has not been adequately understood. This problem is tackled by studying the influence of two isomeric A'-site ligands, linear-shaped n-butylammonium (n-BA+ ) and branched iso-butylammonium (iso-BA+ ), on 2D perovskites from precursor to device, with a combination of in situ grazing-incidence wide-angle X-ray scattering and density functional theory. It is found that branched iso-BA+ , due to the lower aggregation enthalpies, tends to form large-size clusters in the precursor solution, which can act as pre-nucleation sites to expedite the crystallization of vertically oriented 2D perovskites. Furthermore, iso-BA+ is less likely to be incorporated into the MAPbI3 lattice than n-BA+ , suppressing the formation of unwanted multi-oriented perovskites. These findings well explain the better device performance of 2D perovskite solar cells based on iso-BA+ and elucidate the fundamental mechanism of ligand structural impact on 2D perovskite crystallization.

Perovskite-like Silver Halide Single-Crystal Microbelt Enables Ultrasensitive Flexible X-ray Detectors.

Lead halide perovskite single crystals have attracted wide interest in the field of X-ray detection due to their excellent photophysical properties. However, their inherent toxicity and high thickness restrict their applications in flexible devices. In this paper, designing a micronanometer-scale X-ray detector based on all-inorganic lead-free CsAg2I3 (CAI) single crystal microbelts (MBs) has addressed the above issues. These CAI single crystal MBs can be synthesized on various substrates with high crystal quality and excellent stability. Based on their excellent characteristics of the CAI MBs, we fabricate single CAI MB devices with an Au/CAI/Au structure, which shows not only good ultraviolet photoresponse characteristics, but also excellent X-ray detection performance. The optimized CAI photodetectors exhibit a responsivity of 23.59 mA/W, a high detectivity of 1010 Jones, and a fast response speed. For X-ray detection performance, a sensitivity of up to 515.49 µC Gyair-1 cm-2 and a detection limit of as low as 14.65 µGyair s-1 are achieved with outstanding operation stability and excellent long-term stability. Furthermore, our devices also showed excellent applicability for X-ray imaging, which is promising for their use in X-ray detection and imaging. Finally, flexible X-ray detectors are fabricated by using thin CAI single-crystal MBs and demonstrate good flexibility under different bending radii and bending cycles. Our work shows the potential for developing highly sensitive flexible integrated micro/nano optoelectronic devices by using lead-free perovskite analogue single crystals.

Backbone Engineering Enables Highly Efficient Polymer Hole-Transporting Materials for Inverted Perovskite Solar Cells.

The interface and crystallinity of perovskite films play a decisive role in determining the device performance, which is significantly influenced by the bottom hole-transporting material (HTM) of inverted perovskite solar cells (PVSCs). Herein, a simple design strategy of polymer HTMs is reported, which can modulate the wettability and promote the anchoring by introducing pyridine units into the polyarylamine backbone, so as to realize efficient and stable inverted PVSCs. The HTM properties can be effectively modified by varying the linkage sites of pyridine units, and 3,5-linked PTAA-P1 particularly demonstrates a more regulated molecular configuration for interacting with perovskites, leading to highly crystalline perovskite films with uniform back contact and reduced defect density. Dopant-free PTAA-P1-based inverted PVSCs have realized remarkable efficiencies of 24.89% (certified value: 24.50%) for small-area (0.08 cm2 ) as well as 23.12% for large-area (1 cm2 ) devices. Moreover, the unencapsulated device maintains over 93% of its initial efficiency after 800 h of maximum power point tracking under simulated AM 1.5G illumination.

Controllable Heterogenous Seeding-Induced Crystallization for High-Efficiency FAPbI3 -Based Perovskite Solar Cells Over 24.

The addition of small seeding particles into a supersaturated solution is one among the most effective approaches to obtain high-quality semiconductor materials via increased crystallization rates. However, limited study is conducted on this approach for the fabrication of perovskite solar cells. Here, a new strategy-"heterogenous seeding-induced crystallization (hetero-SiC)" to assist the growth of FAPbI3 -based perovskite is proposed. In this work, di-tert-butyl(methyl)phosphonium tetrafluoroborate is directly introduced into the precursor, which forms a low-solubility complex with PbI2 . The low-solubility complex can serve as the seed to induce crystallization of the perovskite during the solvent-evaporation process. Various in situ measurement tools are used to visualize the hetero-SiC process, which is shown to be an effective way of manipulating the nucleation and crystal growth of perovskites. The hetero-SiC process greatly improves the film quality, reduces film defects, and suppresses nonradiative recombination. A hetero-SIC proof-of-concept device exhibits outstanding performance with 24.0% power conversion efficiency (PCE), well over the control device with 22.2% PCE. Additionally, hetero-SiC perovskite solar cell (PSC) stability under light illumination is enhanced and the PSC retains 84% of its initial performance after 1400 h of light illumination.

Expression of CHL1 in Clear Cell Renal Cell Carcinoma and its Association With Prognosis.

As a member of the L1 family of neural cell molecules, close homologue of L1 (CHL1) has been proved to be downregulated in several human cancers. In the present study, we aimed to assess the expression and prognostic value of CHL1 in clear cell renal cell carcinoma (CCRCC). Immunohistochemistry was performed to detect the expression of CHL1 in tissue microarray chips. Then we compared specific clinicopathologic features in patients with different CHL1 expressions. The correlation between CHL1 expression and overall survival (OS) was evaluated by the Kaplan-Meier method and Cox regression analysis. We found that the expression of CHL1 was significantly lower in CCRCC tissues compared with adjacent normal tissues, which was correlated with TNM stage (P<0.001), Fuhrman grade (P=0.006), and LVI (P=0.004). The Kaplan-Meier survival analysis indicated that CCRCC patients with low CHL1 expression had a poorer OS rate than those with high CHL1 expression (P<0.001). Univariate and multivariate Cox regression analyses suggested that CHL1 was an independent and unfavorable prognostic factor for the OS rate of CCRCC patients. Collectively, low expression of CHL1 might predict poor OS rate of CCRCC.

Manipulating Crystallization Kinetics in High-Performance Blade-Coated Perovskite Solar Cells via Cosolvent-Assisted Phase Transition.

Manipulating the perovskite solidification process, including nucleation and crystal growth, plays a critical role in controlling film morphology and thus affects the resultant device performance. In this work, a facile and effective ethyl alcohol (EtOH) cosolvent strategy is demonstrated with the incorporation of EtOH into perovskite ink for high-performance room-temperature blade-coated perovskite solar cells (PSCs) and modules. Systematic real-time perovskite crystallization studies uncover the delicate perovskite structural evolutions and phase-transition pathway. Time-resolved X-ray diffraction and density functional theory calculations both demonstrate that EtOH in the mixed-solvent system significantly promotes the formation of an FA-based precursor solvate (FA2 PbBr4 ·DMSO) during the trace-solvent-assisted transition process, which finely regulates the balance between nucleation and crystal growth to guarantee high-quality perovskite films. This strategy efficiently suppresses nonradiative recombination and improves efficiencies in both 1.54 (23.19%) and 1.60 eV (22.51%) perovskite systems, which represents one of the highest records for blade-coated PSCs in both small-area devices and minimodules. An excellent VOC deficit as low as 335 mV in the 1.54 eV perovskite system, coincident with the measured nonradiative recombination loss of only 77 mV, is achieved. More importantly, significantly enhanced device stability is another signature of this approach.

Highly oriented MAPbI3 crystals for efficient hole-conductor-free printable mesoscopic perovskite solar cells.

Highly crystalline perovskite films with large grains and few grain boundaries are conducive for efficient and stable perovskite solar cells. Current methods for preparing perovskite films are mostly based on a fast crystallization process, with rapid nucleation and insufficient growth. In this study, MAPbI3 perovskite with inhibited nucleation and promoted growth in the TiO2/ZrO2/carbon triple mesoscopic scaffold was crystallized by modulating the precursor and the crystallization process. N-methylformamide showed high solubility for both methylammonium iodide and PbI2 and hampered the formation of large colloids in the MAPbI3 precursor solution. Furthermore, methylammonium chloride was added to reduce large colloids, which are a possible source of nucleation sites. During the crystallization of MAPbI3, the solvent was removed at a slow controlled speed, to avoid rapid nucleation and provide sufficient time for crystal growth. As a result, highly oriented MAPbI3 crystals with suppressed non-radiative recombination and promoted charge transport were obtained in the triple mesoscopic layer with disordered pores. The corresponding hole-conductor-free, printable mesoscopic perovskite solar cells exhibited a highest power conversion efficiency of 18.82%. The device also exhibited promising long-term operational stability of 1000 h under continuous illumination at maximum power point at 55 ± 5 °C and damp-heat stability of 1340 h aging at 85 °C as well as 85% relative humidity.

Room-temperature multiple ligands-tailored SnO2 quantum dots endow in situ dual-interface binding for upscaling efficient perovskite photovoltaics with high VOC.

The benchmark tin oxide (SnO2) electron transporting layers (ETLs) have enabled remarkable progress in planar perovskite solar cell (PSCs). However, the energy loss is still a challenge due to the lack of "hidden interface" control. We report a novel ligand-tailored ultrafine SnO2 quantum dots (QDs) via a facile rapid room temperature synthesis. Importantly, the ligand-tailored SnO2 QDs ETL with multi-functional terminal groups in situ refines the buried interfaces with both the perovskite and transparent electrode via enhanced interface binding and perovskite passivation. These novel ETLs induce synergistic effects of physical and chemical interfacial modulation and preferred perovskite crystallization-directing, delivering reduced interface defects, suppressed non-radiative recombination and elongated charge carrier lifetime. Power conversion efficiency (PCE) of 23.02% (0.04 cm2) and 21.6% (0.98 cm2, VOC loss: 0.336 V) have been achieved for the blade-coated PSCs (1.54 eV Eg) with our new ETLs, representing a record for SnO2 based blade-coated PSCs. Moreover, a substantially enhanced PCE (VOC) from 20.4% (1.15 V) to 22.8% (1.24 V, 90 mV higher VOC, 0.04 cm2 device) in the blade-coated 1.61 eV PSCs system, via replacing the benchmark commercial colloidal SnO2 with our new ETLs.

A Systematic Review of Metal Halide Perovskite Crystallization and Film Formation Mechanism Unveiled by In Situ GIWAXS.

Metal halide perovskites are of fundamental interest in the research of modern thin-film optoelectronic devices, owing to their widely tunable optoelectronic properties and solution processability. To obtain high-quality perovskite films and ultimately high-performance perovskite devices, it is crucial to understand the film formation mechanisms, which, however, remains a great challenge, due to the complexity of perovskite composition, dimensionality, and processing conditions. Nevertheless, the state-of-the-art in situ grazing-incidence wide-angle X-ray scattering (GIWAXS) technique enables one to bridge the complex information with device performance by revealing the crystallization pathways during the perovskite film formation process. In this review, the authors illustrate how to obtain and understand in situ GIWAXS data, summarize and assess recent results of in situ GIWAXS studies on versatile perovskite photovoltaic systems, aiming at elucidating the distinct features and common ground of film formation mechanisms, and shedding light on future opportunities of employing in situ GIWAXS to study the fundamental working mechanisms of highly efficient and stable perovskite solar cells toward mass production.

Uncovering the out-of-plane nanomorphology of organic photovoltaic bulk heterojunction by GTSAXS.

The bulk morphology of the active layer of organic solar cells (OSCs) is known to be crucial to the device performance. The thin film device structure breaks the symmetry into the in-plane direction and out-of-plane direction with respect to the substrate, leading to an intrinsic anisotropy in the bulk morphology. However, the characterization of out-of-plane nanomorphology within the active layer remains a grand challenge. Here, we utilized an X-ray scattering technique, Grazing-incident Transmission Small-angle X-ray Scattering (GTSAXS), to uncover this new morphology dimension. This technique was implemented on the model systems based on fullerene derivative (P3HT:PC71BM) and non-fullerene systems (PBDBT:ITIC, PM6:Y6), which demonstrated the successful extraction of the quantitative out-of-plane acceptor domain size of OSC systems. The detected in-plane and out-of-plane domain sizes show strong correlations with the device performance, particularly in terms of exciton dissociation and charge transfer. With the help of GTSAXS, one could obtain a more fundamental perception about the three-dimensional nanomorphology and new angles for morphology control strategies towards highly efficient photovoltaic devices.