Highlights
4-Terminal inorganic perovskite/organic tandem solar cells were made by using semi-transparent inorganic perovskite solar cells and narrow-bandgap organic solar cells as the sub-cells, ...yielding a power conversion efficiency of 22.34%, which is the highest efficiency for inorganic perovskite/organic tandem solar cells.
Inorganic perovskite solar cells made by drop-coating (self-spreading) gave much higher power conversion efficiency than the cells made by spin-coating, enabling perovskite/organic tandem solar cells with higher efficiency.
After fast developing of single-junction perovskite solar cells and organic solar cells in the past 10 years, it is becoming harder and harder to improve their power conversion efficiencies. Tandem solar cells are receiving more and more attention because they have much higher theoretical efficiency than single-junction solar cells. Good device performance has been achieved for perovskite/silicon and perovskite/perovskite tandem solar cells, including 2-terminal and 4-terminal structures. However, very few studies have been done about 4-terminal inorganic perovskite/organic tandem solar cells. In this work, semi-transparent inorganic perovskite solar cells and organic solar cells are used to fabricate 4-terminal inorganic perovskite/organic tandem solar cells, achieving a power conversion efficiency of 21.25% for the tandem cells with spin-coated perovskite layer. By using drop-coating instead of spin-coating to make the inorganic perovskite films, 4-terminal tandem cells with an efficiency of 22.34% are made. The efficiency is higher than the reported 2-terminal and 4-terminal inorganic perovskite/organic tandem solar cells. In addition, equivalent 2-terminal tandem solar cells were fabricated by connecting the sub-cells in series. The stability of organic solar cells under continuous illumination is improved by using semi-transparent perovskite solar cells as filter.
Inorganic perovskite solar cells (PSCs) suffer from serious carrier recombination and open‐circuit voltage loss because of surface defects and unfavorable energy level alignment. Herein, a polylactic ...acid (PLA) modification approach to improve the performance of mixed‐halide inorganic perovskites is reported. First, the surface defects are effectively passivated through strong interaction between C═O in PLA and undercoordinated Pb2+. Second, secondary grain growth is induced by PLA modification, resulting in larger grain sizes. Third, PLA modification makes the surface region of perovskite change from n‐ to p‐type, favoring charge transport from perovskite to the hole transport layer (HTL). The PLA modified films enable PSCs with less nonradiative recombination and lower energy loss. Consequently, record PCEs of 19.12% and 18.05% are achieved for CsPbI2.25Br0.75 and CsPbI2Br PSCs, respectively. The PSC with an active area of 1 cm2 shows a PCE of 16.41%. A PCE of 14.70% is achieved for HTL‐free PSC with carbon electrode. In addition, the PSC with PLA modification shows significantly improved air stability due to the hydrophobic PLA coating. This work suggests that PLA surface modification is an effective approach to achieving efficient, stable, scalable, and low‐cost inorganic PSCs.
Polylactic acid (PLA) is used to modify mixed‐halide inorganic perovskites. PLA can passivate the defects and induce n‐type to p‐type transition, favoring charge transfer from perovskite to hole transport layer, thus improving the device performance. Record power conversion efficiencies of 19.12% and 18.05% are achieved for CsPbI2.25Br0.75 and CsPbI2Br solar cells, respectively.
Inorganic perovskites are receiving growing attention due to good thermal stability and fast-improving photovoltaic performance. However, most of the high-efficiency inorganic perovskite solar cells ...(PSCs) were fabricated in inert atmosphere. Herein, we report an additive-assisted airflow drying (AAD) method to make mixed-halide inorganic perovskite films in ambient air. The nucleation and crystal growth during film formation are controlled by using airflow dying and lead acetate trihydrate additive, producing pinhole-free film with low defect density. Consequently, efficiency of CsPbI2.25Br0.75 PSCs is improved to 18.49%, which is the highest for wide-bandgap (>1.8 eV) inorganic PSCs. An efficiency of 17.08% is achieved for PSCs made under moderate relative humidity (40–50%). Moreover, PCEs of 17.39% and 11.54% are achieved for CsPbI2Br and CsPbIBr2 PSCs, respectively, which are among the best PCEs for CsPbI2Br and CsPbIBr2 PSCs. This work provides a convenient and efficient method to make efficient inorganic PSCs in ambient air.
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•A facile additive-assisted airflow drying method is developed to make inorganic perovskite films by drop-coating in air.•CsPbI2.25Br0.75 PSCs made in air give a PCE of 18.49%, which is the highest PCE for wide-bandgap (>1.8 eV) inorganic PSCs.•PCEs of 17.39% and 11.54% are achieved for CsPbI2Br and CsPbIBr2 solar cells, respectively.•CsPbI2.25Br0.75 solar cells with an effective area of 1 cm2 delivered a PCE of 15.22%.
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The power conversion efficiency for single-junction solar cells is limited by the Shockley-Quiesser limit. An effective approach to realize high efficiency is to develop ...multi-junction cells. These years have witnessed the rapid development of organic–inorganic perovskite solar cells. The excellent optoelectronic properties and tunable bandgaps of perovskite materials make them potential candidates for developing tandem solar cells, by combining with silicon, Cu(In,Ga)Se2 and organic solar cells. In this review, we present the recent progress of perovskite-based tandem solar cells, including perovskite/silicon, perovskite/perovskite, perovskite/Cu(In,Ga)Se2, and perovskite/organic cells. Finally, the challenges and opportunities for perovskite-based tandem solar cells are discussed.
Abstract The two‐step sequential deposition method exhibits favorable operability for processing perovskite films. Due to the growth of the perovskite films largely depends on the pre‐deposited PbI 2 ...films, the porous and rough PbI 2 films are expected to facilitate the penetration of the organic amine salts. However, in air conditions, the porous and rough PbI 2 films also facilitate the penetration of the water molecules, thus leading to diminished crystallinity. Despite substantial efforts aimed at inhibiting the decomposition of perovskite films, the performance of air‐processed perovskite solar cells (PSCs) remains unsatisfactory. Herein, the study presents that the PbI 2 films with high exposure of layered planes and vanished of non‐layered planes have more effective to resist water erosion and promote the crystallization process of perovskite films. An amphoteric Lewis acid‐base molecule (cephalothin, a type of antibiotic) is added in PbI 2 precursor solution to induce this highly layer‐oriented PbI 2 film. Consequently, the perovskite films can be processed under humidity condition and yield the champion PSC with an outstanding power conversion efficiency of 24.45%. In addition, the unencapsulated devices maintain 80% of their initial power conversion efficiency after 1000 h storage in air and exhibit high thermal stability after 100 cycles at 25–70 °C.
•Cu2SrSnS4 (CSTS) thin films synthesized via a sol-gel based solution process.•Morphological, phases and optical properties of CSTS thin films characterized.•600 °C annealing and Sr/Sn atomic ratios ...of 1.15 were the best preparation conditions.•Champion CSTS solar cell with 0.164% power conversion efficiency obtained.•Feasibility of solar energy harvesting of CSTS material demonstrated.
According to theory calculation, the Cu2SrSnS4 (CSTS) become a candidate material for harvesting solar energy via either photovoltaic (PV) or photoelectrochemical (PEC) paths due to its efficient light-absorbing capability (high absorption coefficients above 104 cm−1), earth-abundant, nontoxic constituents, and suitable defect properties. As a new material, there is a long way to accomplish the application of CSTS. Film preparation of CSTS are very critical. In this work, CSTS thin films were synthesized by a sol-gel based solution process. The obtained CSTS films showed trigonal structure with band gap of 1.93 eV and p-type conductivity. By comparing the CSTS thin films synthesized with different annealed temperature and Sr/Sn atomic ratios, we confirmed that sulfurization annealing at 600 °C and Sr/Sn atomic ratios of 1.15 yields relatively high quality CSTS films. A PEC cell using the CSTS thin film as working electrode were established and a saturated photocurrent of ∼0.5 mA/cm2 had been achieved. It has also been applied to a PV device, demonstrating open-circuit voltage of 296 mV and power conversion efficiency of 0.164%. Pinholes in the films and reef-like grains at the surface of CSTS films were likely to limit the devices performance. The feasibility of solar energy harvesting of CSTS material was demonstrated.
Allele-specific expression (ASE) analysis, which quantifies the relative expression of two alleles in a diploid individual, is a powerful tool for identifying cis-regulated gene expression variations ...that underlie phenotypic differences among individuals. Existing methods for gene-level ASE detection analyze one individual at a time, therefore failing to account for shared information across individuals. Failure to accommodate such shared information not only reduces power, but also makes it difficult to interpret results across individuals. However, when only RNA sequencing (RNA-seq) data are available, ASE detection across individuals is challenging because the data often include individuals that are either heterozygous or homozygous for the unobserved cis-regulatory SNP, leading to sample heterogeneity as only those heterozygous individuals are informative for ASE, whereas those homozygous individuals have balanced expression. To simultaneously model multi-individual information and account for such heterogeneity, we developed ASEP, a mixture model with subject-specific random effect to account for multi-SNP correlations within the same gene. ASEP only requires RNA-seq data, and is able to detect gene-level ASE under one condition and differential ASE between two conditions (e.g., pre- versus post-treatment). Extensive simulations demonstrated the convincing performance of ASEP under a wide range of scenarios. We applied ASEP to a human kidney RNA-seq dataset, identified ASE genes and validated our results with two published eQTL studies. We further applied ASEP to a human macrophage RNA-seq dataset, identified genes showing evidence of differential ASE between M0 and M1 macrophages, and confirmed our findings by results from cardiometabolic trait-relevant genome-wide association studies. To the best of our knowledge, ASEP is the first method for gene-level ASE detection at the population level that only requires the use of RNA-seq data. With the growing adoption of RNA-seq, we believe ASEP will be well-suited for various ASE studies for human diseases.
A novel Cu-Cr-Yb alloy was designed and processed by thermo-mechanical treatment. The microstructure, mechanical and electrical properties were investigated in detail. The results showed that the ...Cu-Cr-Yb alloy had a higher strength, a better softening resistance and a considerably high electrical conductivity than the Cu-Cr alloy. After 80% cold rolling followed by aging at 500 °C, the peak-aged Cu-Cr-Yb alloy had a Vickers hardness of 160 ± 1 HV, a tensile strength of 465 MPa, an elongation of 21.1% and an electrical conductivity of 89.5 %IACS, respectively. After a long-time aging at 500 °C, the nano-scale Cr-rich precipitates with FCC structure in the Cu-Cr-Yb alloy hardly coarsened. Thermodynamics analysis showed that the Cr-rich precipitates were inclined to nucleate with FCC structure, and the addition of Yb hindered the nucleation of the Cr-rich precipitates.
•Cu-Cr-Yb alloy had better comprehensive properties than Cu-Cr alloy.•Nano-scale Cr-rich precipitates in Cu-Cr-Yb alloy hardly coarsened.•Yb hindered the nucleation of the Cr-rich precipitates.
The mechanisms underlying glucocorticoid (GC)-increased adiposity are poorly understood. Brown adipose tissue (BAT) acquires white adipose tissue (WAT) cell features defined as BAT whitening under ...certain circumstances. The aim of our current study was to investigate the possibility and mechanisms of GC-induced BAT whitening. Here, we showed that one-week dexamethasone (Dex) treatment induced BAT whitening, characterized by lipid droplet accumulation, in vitro and in vivo. Furthermore, autophagy and ATG7 (autophagy related 7) expression was induced in BAT by Dex, and treatment with the autophagy inhibitor chloroquine or adenovirus-mediated ATG7 knockdown prevented Dex-induced BAT whitening and fat mass gain. Moreover, Dex-increased ATG7 expression and autophagy was mediated by enhanced expression of BTG1 (B cell translocation gene 1, anti-proliferative) that stimulated activity of CREB1 (cAMP response element binding protein 1). The importance of BTG1 in this regulation was further demonstrated by the observed BAT whitening in adipocyte-specific BTG1-overexpressing mice and the attenuated Dex-induced BAT whitening and fat mass gain in mice with BTG1 knockdown in BAT. Taken together, we showed that Dex induces a significant whitening of BAT via BTG1- and ATG7-dependent autophagy, which might contribute to Dex-increased adiposity. These results provide new insights into the mechanisms underlying GC-increased adiposity and possible strategy for preventing GC-induced side effects via the combined use of an autophagy inhibitor.
ACADL: acyl-Coenzyme A dehydrogenase, long-chain; ACADM: acyl-Coenzyme A dehydrogenase, medium-chain; ACADS: acyl-Coenzyme A dehydrogenase, short-chain; ADIPOQ: adiponectin; AGT: angiotensinogen; Atg: autophagy-related; BAT: brown adipose tissue; BTG1: B cell translocation gene 1, anti-proliferative; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; CIDEA: cell death-inducing DNA fragmentation factor, alpha subunit-like effector A; CPT1B: carnitine palmitoyltransferase 1b, muscle; CPT2: carnitine palmitoyltransferase 2; CQ: chloroquine; Dex: dexamethasone; eWAT: epididymal white adipose tissue; FABP4: fatty acid binding protein 4, adipocyte; FFAs: free fatty acids; GCs: glucocorticoids; NRIP1: nuclear receptor interacting protein 1; OCR: oxygen consumption rate; PBS: phosphate-buffered saline; PPARA: peroxisome proliferator activated receptor alpha; PPARG: peroxisome proliferator activated receptor gamma; PPARGC1A: peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; PRDM16: PR domain containing 16; PSAT1: phosphoserine aminotransferase 1; RB1: RB transcriptional corepressor 1; RBL1/p107: RB transcriptional corepressor like 1; SQSTM1: sequestosome 1; sWAT: subcutaneous white adipose tissue; TG: triglycerides; UCP1: uncoupling protein 1 (mitochondrial, proton carrier); WT: wild-type
Abstract Weak-line quasars (WLQs) are a notable group of active galactic nuclei (AGNs) that show unusually weak UV lines even though their optical-UV continuum shapes are similar to those of typical ...quasars. The physical mechanism for WLQs is an unsolved puzzle in the AGN unified model. We explore the properties of UV emission lines by performing extensive photoionization calculations based on Cloudy simulations with different spectral energy distributions (SEDs) of AGNs. The AGN continua are built from several observational empirical correlations, where the blackbody emission from the cold disk, the power-law emission from the hot corona, and a soft X-ray excess component are considered. We find that the equivalent width (EW) of C iv from our models is systematically lower than observational values if the component of soft X-ray excess is neglected. The EW will increase several times and is roughly consistent with the observations after considering the soft X-ray excess component as constrained from normal type I AGNs. We find that the UV lines are weak for QSOs with quite large black hole mass (e.g., M BH > 10 9 M ⊙ ) and weak soft X-ray emission due to the deficit of ionizing photons. As an example, we present the strength of C iv based on the multiband SEDs for three nearby weak-line AGNs, where the weaker soft X-ray emission normally predicts the weaker lines.
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