Room-Temperature Processing of Inorganic Perovskite Films to Enable Flexible Solar Cells

Inorganic lead halide perovskite materials have attracted great attention recently due to their potential for greater thermal stability compared to hybrid organic perovskites. However, the high processing temperature to convert from the non-perovskite phase to cubic perovskite phase in many of these systems has limited their application in flexible optoelectronic devices. Here, we report a room temperature processed inorganic PSC based on CsPbI2Br as the light harvesting layer. By combing this composition with key precursor solvents, we show that the inorganic perovskite film can be prepared by the vacuum-assist method under room temperature conditions in air. Unencapsulated devices achieved the power conversion efficiency up to 8.67% when measured under 1-sun irradiation. Exploiting this room temperature process, flexible inorganic PSCs based on an inorganic metal halide perovskite material is demonstrated.Comment: 23 pages, 4 figures, and supplemental informatio

Practical Roadmap and Limits to Nanostructured Photovoltaics

The significant research interest in the engineering of photovoltaic (PV) structures at the nanoscale is directed toward enabling reductions in PV module fabrication and installation costs as well as improving cell power conversion efficiency (PCE). With the emergence of a multitude of nanostructured photovoltaic (nano-PV) device architectures, the question has arisen of where both the practical and the fundamental limits of performance reside in these new systems. Here, the former is addressed a posteriori. The specific challenges associated with improving the electrical power conversion efficiency of various nano-PV technologies are discussed and several approaches to reduce their thermal losses beyond the single bandgap limit are reviewed. Critical considerations related to the module lifetime and cost that are unique to nano-PV architectures are also addressed. The analysis suggests that a practical single-junction laboratory power conversion efficiency limit of 17% and a two-cell tandem power conversion efficiency limit of 24% are possible for nano-PVs, which, when combined with operating lifetimes of 10 to 15 years, could position them as a transformational technology for solar energy markets.Eni-MIT Alliance Solar Frontiers Program (Eni S.p.A. (Firm))National Science Foundation (U.S.). Graduate Research Fellowship ProgramLink FoundationHertz Foundation (Fellowship

Toward Efficient Carbon Nanotube/P3HT Solar Cells: Active Layer Morphology, Electrical, and Optical Properties

We demonstrate single-walled carbon nanotube (SWCNT)/P3HT polymer bulk heterojunction solar cells with an AM1.5 efficiency of 0.72%, significantly higher than previously reported (0.05%). A key step in achieving high efficiency is the utilization of semiconducting SWCNTs coated with an ordered P3HT layer to enhance the charge separation and transport in the device active layer. Electrical characteristics of devices with SWCNT concentrations up to 40 wt % were measured and are shown to be strongly dependent on the SWCNT loading. A maximum open circuit voltage was measured for SWCNT concentration of 3 wt % with a value of 1.04 V, higher than expected based on the interface band alignment. Modeling of the open-circuit voltage suggests that despite the large carrier mobility in SWCNTs device power conversion efficiency is governed by carrier recombination. Optical characterization shows that only SWCNT with diameter of 1.3–1.4 nm can contribute to the photocurrent with internal quantum efficiency up to 26%. Our results advance the fundamental understanding and improve the design of efficient polymer/SWCNTs solar cells

Unlocking the Single‐Domain Epitaxy of Halide Perovskites

The growth of epitaxial semiconductors and oxides has long since revolutionized the electronics and optics fields, and continues to be exploited to uncover new physics stemming from quantum interactions. While the recent emergence of halide perovskites offers exciting new opportunities for a range of thin‐film electronics, the principles of epitaxy have yet to be applied to this new class of materials and the full potential of these materials is still not yet known. In this work, single‐domain inorganic halide perovskite epitaxy is demonstrated. This is enabled by reactive vapor phase deposition onto single crystal metal halide substrates with congruent ionic interactions. For the archetypical halide perovskite, cesium tin bromide, two epitaxial phases, a cubic phase and tetragonal phase, are uncovered which emerge via stoichiometry control that are both stabilized with vastly differing lattice constants and accommodated via epitaxial rotation. This epitaxial growth is exploited to demonstrate multilayer 2D quantum wells of a halide‐perovskite system. This work ultimately unlocks new routes to push halide perovskites to their full potential.Single‐domain halide perovskite heteroepitaxy is demonstrated and multiple epitaxial phases of archetypical halide perovskite are uncovered via stiochiometry control. The epitaxial growth is further exploited to demonstrate multilayer 2D quantum wells of a halide‐perovskite system and can ultimately enable their full potential in many emerging applications.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140019/1/admi201701003-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/140019/2/admi201701003_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/140019/3/admi201701003.pd

Mutations in GATA2 cause primary lymphedema associated with a predisposition to acute myeloid leukemia (Emberger syndrome).

We report an allelic series of eight mutations in GATA2 underlying Emberger syndrome, an autosomal dominant primary lymphedema associated with a predisposition to acute myeloid leukemia. GATA2 is a transcription factor that plays an essential role in gene regulation during vascular development and hematopoietic differentiation. Our findings indicate that haploinsufficiency of GATA2 underlies primary lymphedema and predisposes to acute myeloid leukemia in this syndrome

Early Jurassic North Atlantic sea-surface temperatures from TEX₈₆palaeothermometry

Early Jurassic marine palaeotemperatures have been typically quantified by oxygen-isotope palaeothermometry of benthic and nektonic carbonate and phosphatic macrofossils. However, records of Early Jurassic sea-surface temperatures (SSTs) that can be directly compared with General Circulation Model (GCM) simulations of past climates are currently unavailable. The TEX86 SST proxy is based upon the relative abundance of glycerol dialkyl glycerol tetraethers (GDGTs) preserved in organic-carbon-bearing sediments. This proxy has been used extensively on Cretaceous and Cenozoic materials and, in one study, Middle and Upper Jurassic sediments. Here TEX86 is applied, for the first time, to Lower Jurassic (Sinemurian–Pliensbachian) sediments cored at Deep Sea Drilling Project Site 547 in the North Atlantic. The abundance of GDGTs in these sediments is very low, despite biomarker and Rock-Eval data suggesting that thermal maturity is, generally, low. Sea-floor oxygenation and a high input of reworked terrestrially sourced organic matter may explain the low concentrations. For samples from which it was possible to quantify the relative abundance of GDGTs, TEX86 values range from 0.78 to 0.88, equating to SSTs in excess of >28˚C. These temperatures are broadly comparable with new GCM simulations of the Sinemurian and Pliensbachian stages and support the general view of a predominantly warm climate. The new proxy data suggest that, under favourable geological conditions, it is possible to extend the record of TEX86-based SSTs back into the Early Jurassic

Development of a Colon Cancer GEMM-Derived Orthotopic Transplant Model for Drug Discovery and Validation

Purpose: Effective therapies for KRAS-mutant colorectal cancer (CRC) are a critical unmet clinical need. Previously, we described genetically engineered mouse models (GEMM) for sporadic Kras-mutant and non-mutant CRC suitable for preclinical evaluation of experimental therapeutics. To accelerate drug discovery and validation, we sought to derive low-passage cell lines from GEMM Kras-mutant and wild-type tumors for in vitro screening and transplantation into the native colonic environment of immunocompetent mice for in vivo validation. Experimental Design: Cell lines were derived from Kras-mutant and non-mutant GEMM tumors under defined media conditions. Growth kinetics, phosphoproteomes, transcriptomes, drug sensitivity, and metabolism were examined. Cell lines were implanted in mice and monitored for in vivo tumor analysis. Results: Kras-mutant cell lines displayed increased proliferation, mitogen-activated protein kinase signaling, and phosphoinositide-3 kinase signaling. Microarray analysis identified significant overlap with human CRC-related gene signatures, including KRAS-mutant and metastatic CRC. Further analyses revealed enrichment for numerous disease-relevant biologic pathways, including glucose metabolism. Functional assessment in vitro and in vivo validated this finding and highlighted the dependence of Kras-mutant CRC on oncogenic signaling and on aerobic glycolysis. Conclusions: We have successfully characterized a novel GEMM-derived orthotopic transplant model of human KRAS-mutant CRC. This approach combines in vitro screening capability using low-passage cell lines that recapitulate human CRC and potential for rapid in vivo validation using cell line-derived tumors that develop in the colonic microenvironment of immunocompetent animals. Taken together, this platform is a clear advancement in preclinical CRC models for comprehensive drug discovery and validation efforts