Regulating Charge Transport Dynamics at the Buried Interface and Bulk of Perovskites by Tailored-phase Two-dimensional Crystal Seed Layer.

Targeting the trap-assisted non-radiative recombination losses and photochemical degradation occurring at the interface and bulk of perovskite, especially the overlooked buried bottom interface, a strategy of tailored-phase two-dimensional (TP-2D) crystal seed layer has been developed to improve the charge transport dynamics at the buried interface and bulk of perovskite films. Using this approach, TP-2D layer constructed by TP-2D crystal seeds at the buried interface can induce the formation of homogeneous interface electric field, which effectively suppress the accumulation of charge carriers at the buried interface. Additionally, the presence of TP-2D crystal seed has a positive effect on the crystallization process of the upper perovskite film, leading to optimized crystal quality and thus promoted charge transport inside bulk perovskites. Ultimately, the best performing PSCs based on TP-2D layer deliver a power conversion efficiency of 24.58 %. The devices exhibit an improved photostability with 88.4 % of their initial PCEs being retained after aging under continuous 0.8-sun illumination for 2000 h in air. Our findings reveal how to regulate the charge transport dynamics of perovskite bulk and interface by introducing homogeneous components.

Suppressed Ion Migration in FA-Rich Perovskite Photovoltaics through Enhanced Nucleation of Encapsulation Interface.

With excellent homogeneity, compactness and controllable thickness, atomic layer deposition (ALD) technology is widely used in perovskite solar cells (PSCs). However, residual organic sources and undesired reactions pose serious challenges to device performance as well as stability. Here, ester groups of poly(ethylene-co-vinyl acetate) are introduced as a reaction medium to promote the nucleation and complete conversion of tetrakis(dimethylamino)tin(IV) (TDMA-Sn). Through simulations and experiments, it is verified that ester groups as Lewis bases can coordinate with TDMA-Sn to facilitate homogeneous deposition of ALD-SnOx , which acts as self-encapsulated interface with blocking properties against external moisture as well as internal ion migration. Meanwhile, a comprehensive evaluation of the self-encapsulated interface reveals that the energy level alignment is optimized to improve the carrier transport. Finally, the self-encapsulated device obtains a champion photovoltaic conversion efficiency (PCE) of 22.06% and retains 85% of the initial PCE after being stored at 85 °C with relative humidity of 85% for more than 800 h.

Spontaneous Internal Encapsulation via Dual Interfacial Perovskite Heterojunction Enables Highly Efficient and Stable Perovskite Solar Cells.

Deep traps stemming from the defects formed at the surfaces and grain boundaries of the perovskite films are the main reasons of nonradiative recombination and material degradation, which significantly affect efficiency and stability of perovskite solar cells (PSCs). Here, a spontaneous internal encapsulation strategy was developed by constructing a dual interfacial perovskite heterojunction at the top and buried interface of the three-dimensional (3D) perovskite film. The spacer cations of the two-dimensional (2D) perovskite structure interacted strongly with the 3D perovskite to passivate the defects and optimize the energy level alignment. Meanwhile, the interfacial perovskite heterojunction underearth delayed the crystallization speed and improved the crystallization quality of the upper 3D perovskite. Thanks to these positive effects, the PSC exhibited a power conversion efficiency of 22.92% with good reproducibility. Significantly, the unencapsulated device with the dual interfacial perovskite heterojunction maintained 88% of its initial efficiency after 2900 h under 65 ± 5% RH in air.

Ionic Liquid Assisted Imprint for Efficient and Stable Quasi-2D Perovskite Solar Cells with Controlled Phase Distribution.

Although two-dimensional perovskite devices are highly stable, they also lead to a number of challenges. For instance, the introduction of large organic amines makes crystallization process complicated, causing problems such as generally small grain size and blocked charge transfer. In this work, imprint assisted with methylamine acetate were used to improve the morphology of the film, optimize the internal phase distribution, and enhance the charge transfer of the perovskite film. Specifically, imprint promoted the dispersion of spacer cations in the recrystallization process with the assistance of methylamine acetate, thus inhibited the formation of low-n phase induced by the aggregation of spacer cations and facilitated the formation of 3D-like phase. In this case, the corresponding quasi-2D perovskite solar cells delivered improved efficiency and exhibited superior stability. Our work provides an effective strategy to obtain uniform phase distribution for quasi-2D perovskite.

Modulation of Colloidal Assembly Behavior Enables Printable Low-Dimensional Perovskite Photovoltaics.

The multiple quantum wells (QWs) distribution in low-dimensional perovskite films hinders charge transport due to the fundamental difficulty of controlling crystal growth from precursor solutions, yielding poorly homogeneous low-dimensional perovskite solar cells (PSCs), especially in upscaling fabrication. Here, efficient low-dimensional PSCs are realized by modulating the colloidal assembly behavior in the precursor solution to induce intermediate structures. In combination with in situ liquid time-of-flight secondary ion mass spectrometry, the assembly behavior of organic cations involved lead iodide-dominated colloidal soft framework is visualized by investigating the precursor species differences under hydrogen bonding interactions. Subsequently, solid-state reactions emerge and the formamidine (FA)-based perovskite films exhibit significantly suppressed multiple QWs distribution. Encouragingly, the FA device (n=9, by meniscus-assisted coating) achieves a power conversion efficiency (PCE) of 20.28 % for a size of 0.04 cm2 and a PCE of 15.35 % for a mini-module of 16.94 cm2 with superior stability.

Spontaneous Formation of Upper Gradient 2D Structure for Efficient and Stable Quasi-2D Perovskites.

Highly efficient and stable quasi-2D hybrid perovskite solar cells (PSCs) using hydrophobic 4-(trifluoromethyl) benzylamine (4TFBZA) as the spacer cation are successfully demonstrated. It is found that the incorporation of hydrophobic 4TFBZA into MAPbI3 can effectively induce a spontaneous upper gradient 2D (SUG-2D) structure, passivate the trap states, and restrain the ion motion. Meanwhile, the strong hydrogen bonding of F···HN between 4TFBZA ions and methylamine ions can effectively suppress the decomposition of perovskite, which gives the device a better thermal stability. Besides, due to the SUG-2D structure with hydrophobic 4TFBZA, the device also exhibits a better moisture stability. The SUG-2D-structure-based device exhibits a power conversion efficiency of 17.07% with a high open-circuit voltage of 1.10 V and a notable fill factor of 71%. This work provides a new strategy for constructing efficient and stable quasi-2D PSCs, and it is an inspiration for the packaging strategy of perovskites.

Association of five genetic variants with chronic obstructive pulmonary disease susceptibility and spirometric phenotypes in a Chinese Han population.

BACKGROUND AND OBJECTIVE: Recent genome-wide association studies have shown associations between variants at five loci (TNS1, GSTCD, HTR4, AGER and THSD4) and chronic obstructive pulmonary disease (COPD) or lung function. However, their association with COPD has not been proven in Chinese Han population, nor have COPD-related phenotypes been studied. The objective of this study was to look for associations between five single nucleotide polymorphisms (SNP) in these novel candidate genes and COPD susceptibility or lung function in a Chinese Han population. METHODS: Allele and genotype data on 680 COPD patients and 687 healthy controls for sentinel SNP in these five loci were investigated. Allele frequencies and genotype distributions were compared between cases and controls, and odds ratios were calculated. Potential relationships between these SNP and COPD-related lung function were assessed. RESULTS: No significant associations were found between any of the SNP and COPD in cases and controls. The SNP (rs3995090) in HTR4 was associated with COPD (adjusted P = 0.022) in never-smokers, and the SNP (rs2070600) in AGER was associated with forced expiratory volume in 1 s (FEV1 %) predicted (ß = -0.066, adjusted P = 0.016) and FEV1 /forced vital capacity (ß = -0.071, adjusted P = 0.009) in all subjects. CONCLUSIONS: The variant at HTR4 was associated with COPD in never-smokers, and the SNP in AGER was associated with pulmonary function in a Chinese Han population.

Association of HHIP polymorphisms with COPD and COPD-related phenotypes in a Chinese Han population.

The hedgehog signaling pathway plays an important role in lung morphogenesis and cellular responses to lung injury. Genome-wide association studies (GWAS) and integrative genomics approaches have demonstrated the associations between HHIP polymorphisms and chronic obstructive pulmonary disease (COPD) and in non-Asian populations. Here we investigated whether HHIP polymorphisms would also be associated with COPD susceptibility and COPD-related phenotypes in a Chinese Han population. In the present case-control study a total of 680 COPD patients and 687 healthy control subjects were recruited. Six single nucleotide polymorphisms (SNPs) (rs1828591, rs13118928, rs6817273, rs10519717, rs12504628, rs13147758) were selected for genotyping. Allele frequencies and genotype distributions were compared between patients and controls. To estimate the strength of association, odds ratios (OR) (with 95% CI) were calculated and potential confounding variables were tested by using logistic regression analysis. Association between haplotypes and COPD outcome was also assessed. We identified that SNP rs12504628 was associated with FEV1/FVC ratio among cases (P=0.0460). Moreover, the HHIP SNP rs10519717 was associated with the severity of disease (adjusted P-value=0.0300). The six SNPs showed strong linkage disequilibrium (r(2)≥ 0.9). Three major haplotypes were observed but showed no significant difference between case and control groups (P=0.4532, 0.0875, and 0.3484, respectively). In conclusion, our study suggests that the HHIP gene may be involved in COPD susceptibility in Chinese Han population.

Association of IREB2 and CHRNA3/5 polymorphisms with COPD and COPD-related phenotypes in a Chinese Han population.

Genome-wide association studies and integrative genomics approaches have demonstrated significant associations between chronic obstructive pulmonary disease (COPD) and single-nucleotide polymorphisms (SNPs) in the chromosome 15q25 region that includes iron-responsive element binding protein 2 gene (IREB2) and CHRNA3/5 in non-Asian populations. We investigated whether IREB2 and CHRNA3/5 polymorphisms would be associated with COPD susceptibility and COPD-related phenotypes in a Chinese Han population. Eight SNPs (rs2568494, rs2656069, rs10851906, rs1964678, rs12593229, rs965604, rs13180, rs17483929) in IREB2 gene and four SNPs (rs16969968, rs1051730, rs938682, rs8034191) in or near CHRNA3/5 locus were genotyped in a case-control study (680 COPD patients and 687 controls). No significant associations were found between any of the SNPs and COPD in either former-smokers or current-smokers. Two SNPs (rs2656069 and rs10851906) in IREB2 were associated with COPD (P=0.045 and 0.032, respectively) in non-smoker. Four SNPs (rs1964678, rs12593229, rs965604 and rs13180) in IREB2 were associated with forced expiratory volume in 1 s (FEV(1))% predicted and three SNPs (rs16969968, rs8034191 and rs1051730) in CHRNA3/5 were both associated with FEV(1)% predicted and FEV(1)/FVC in COPD cases (P range 0.007-0.050). The SNP rs8034191 near CHRNA3/5 locus was significantly associated with pack-years of smoking in COPD patients (P=0.033). We demonstrated IREB2 polymorphisms were associated with COPD in non-smoking subjects, and the effect of IREB2 gene on COPD may be independent from smoking and independent from CHRNA3/5 gene cluster. Besides, we confirmed that SNPs in these two gene loci were associated with pulmonary function and CHRNA3/5 polymorphism was associated with pack-year of smoking in COPD patients in the Chinese Han population.