Cromwell Assisted Pipeline Executor (Caper)

Introduction Caper is based on Unix and cloud platform CLIs (curl, gsutil and aws) and provides easier way of running Cromwell server/run modes by automatically composing necessary input files for Cromwell. Also, Caper supports easy automatic file transfer between local/cloud storages (local path, s3://, gs:// and http(s)://). You can use these URIs in input JSON file or for a WDL file itself.</p

Cromwell Output Organizer (Croo)

Cromwell Output Organizer (Croo) Croo is a Python package for organizing outputs from Cromwell. Introduction Croo parses metadata.json which is an output from Cromwell and makes an organized directory with a copy (or a soft link) of each output file as described in an output definition JSON file specified by --out-def-json. Features Automatic file transfer between local/cloud storages: For example, the following command line works. You can define URIs instead of local path for any command line arguments. The following command line reads from remote metadata JSON file (gs://some/where/metadata.json) and output definition JSON file (s3://over/here/atac.out_def.json) and write organized outputs to gs://your/final/out/bucket. $croo gs://some/where/metadata.json --out-def-json s3://over/here/atac.out_def.json --out-dir gs://your/final/out/bucket Soft-linking (local storage only): Croo defaults to make soft links instead of copying for local-to-local file transfer (local output file defined in a metadata JSON vs. local output directory specifed by --out-dir). In order to force copying instead of soft-linking regardless of a storage type then use --method copy. Local-to-cloud and cloud-to-local file transfer always uses copy method. File table, task graph with clickable links: Croo generates an HTML report with a file table, which is a summary/description of all output files with clickable links for them. Examples: ATAC and ChIP. UCSC browser tracks: Clickable link for UCSC browser tracks in the HTML report.$ croo ... --ucsc-genome-db hg38  </p

van der Waals Metal Contacts for Characterization and Optoelectronic Application of Metal Halide Perovskite Thin Films

The metal contacts on metal halide perovskite thin films are often formed through physical vapor deposition (PVD) processes for investigation of the film properties or construction of optoelectronic devices. However, the PVD processes generate high-energy metal atoms, directly bombarding the film surface, potentially causing unintended damage in the film. In this study, we performed systematic investigation on the impact of a PVD-processed metal contact on the optoelectronic properties of underlying organic–inorganic hybrid perovskite thin films. We adopted a physically laminated van der Waals metal contact for comparison to enable quantitative analysis. Through space-charge-limited current measurement, we demonstrated the defect density increases by 26–48% on average after formation of the metal contact by the PVD process. In-situ photoluminescence measurements unraveled that the generated defects easily migrate under the electric field to seriously deteriorate the performance and stability of photodetectors. This study highlights the importance of the intact junction between the perovskite and metal contacts for characterization and optoelectronic application of perovskite thin films

van der Waals Metal Contacts for Characterization and Optoelectronic Application of Metal Halide Perovskite Thin Films

The metal contacts on metal halide perovskite thin films are often formed through physical vapor deposition (PVD) processes for investigation of the film properties or construction of optoelectronic devices. However, the PVD processes generate high-energy metal atoms, directly bombarding the film surface, potentially causing unintended damage in the film. In this study, we performed systematic investigation on the impact of a PVD-processed metal contact on the optoelectronic properties of underlying organic–inorganic hybrid perovskite thin films. We adopted a physically laminated van der Waals metal contact for comparison to enable quantitative analysis. Through space-charge-limited current measurement, we demonstrated the defect density increases by 26–48% on average after formation of the metal contact by the PVD process. In-situ photoluminescence measurements unraveled that the generated defects easily migrate under the electric field to seriously deteriorate the performance and stability of photodetectors. This study highlights the importance of the intact junction between the perovskite and metal contacts for characterization and optoelectronic application of perovskite thin films

Lewis Acid–Base Adduct Approach for High Efficiency Perovskite Solar Cells

ConspectusSince the first report on the long-term durable 9.7% solid-state perovskite solar cell employing methylammonium lead iodide (CH₃NH₃PbI₃), mesoporous TiO₂, and 2,2′,7,7′-tetrakis­[<i>N</i>,<i>N</i>-di­(4-methoxyphenyl)­amino]-9,9′-spirobifluorene (spiro-MeOTAD) in 2012, following the seed technologies on perovskite-sensitized liquid junction solar cells in 2009 and 2011, a surge of interest has been focused on perovskite solar cells due to superb photovoltaic performance and extremely facile fabrication processes. The power conversion efficiency (PCE) of perovskite solar cells reached 21% in a very short period of time. Such an unprecedentedly high photovoltaic performance is due to the intrinsic optoelectronic property of organolead iodide perovskite material. Moreover, a high dielectric constant, sub-millimeter scale carrier diffusion length, an underlying ferroelectric property, and ion migration behavior can make organolead halide perovskites suitable for multifunctionality. Thus, besides solar cell applications, perovskite material has recently been applied to a variety fields of materials science such as photodetectors, light emitting diodes, lasing, X-ray imaging, resistive memory, and water splitting. Regardless of application areas, the growth of a well-defined perovskite layer with high crystallinity is essential for effective utilization of its excellent physicochemical properties. Therefore, an effective methodology for preparation of high quality perovskite layers is required.In this Account, an effective methodology for production of high quality perovskite layers is described, which is the Lewis acid–base adduct approach. In the solution process to form the perovskite layer, the key chemicals of CH₃NH₃I (or HC­(NH₂)₂I) and PbI₂ are used by dissolving them in polar aprotic solvents. Since polar aprotic solvents bear oxygen, sulfur, or nitrogen, they can act as a Lewis base. In addition, the main group compound PbI₂ is known to be a Lewis acid. Thus, PbI₂ has a chance to form an adduct by reacting with the Lewis base. Crystal growth and morphology of perovskite can be controlled by taking advantage of the weak chemical interaction in the adduct. We have successfully fabricated highly reproducible CH₃NH₃PbI₃ perovskite solar cells with PCE as high as 19.7% via adducts of PbI₂ with oxygen-donor <i>N</i>,<i>N</i>′-dimethyl sulfoxide. This adduct approach has been found to be generally adopted, where formamidinium lead iodide perovskite, HC­(NH₂)₂PbI₃ (FAPbI₃), with large grain, high crystallinity, and long-lived carrier lifetime was successfully fabricated via an adduct of PbI₂ with sulfur-donor thiourea as Lewis base. The adduct approach proposed in this Account is a very promising methodology to achieve high quality perovskite films with high photovoltaic performance. Furthermore, single crystal growth on the conductive substrate is expected to be possible if we kinetically control the elimination of Lewis base in the adduct

Impact of Excess CH₃NH₃I on Free Carrier Dynamics in High-Performance Nonstoichiometric Perovskites

Since the discovery of organometallic trihalide perovskites, there have been tremendous efforts to exploit these hybrid materials and understand their optoelectronic properties for the development of solar cells with high power conversion efficiencies. Although the improved performance of perovskite solar cells with excess CH3NH3I has been reported, the dedicated research of the free charge carrier dynamics is lacking. In this study, we measured the photoluminescence (PL) intensities and lifetimes at the grains and near the grain boundaries of CH3NH3PbI3 perovskite films using spatially and temporally resolved PL spectroscopy. An excess CH3NH3I was found to cause brighter PL intensities and longer PL lifetimes at both the grains and grain boundaries. This comparative investigation of stoichiometric and nonstoichiometric perovskite films enables us to understand the optoelectronic properties induced by excess CH3NH3I, opening a new way for optimization of perovskite solar cells

Artificial Synapse Based on a δ‑FAPbI₃/Atomic-Layer-Deposited SnO₂ Bilayer Memristor

Halide perovskite-based resistive switching memory (memristor) has potential in an artificial synapse. However, an abrupt switch behavior observed for a formamidinium lead triiodide (FAPbI3)-based memristor is undesirable for an artificial synapse. Here, we report on the δ-FAPbI3/atomic-layer-deposited (ALD)-SnO2 bilayer memristor for gradual analogue resistive switching. In comparison to a single-layer δ-FAPbI3 memristor, the heterojunction δ-FAPbI3/ALD-SnO2 bilayer effectively reduces the current level in the high-resistance state. The analog resistive switching characteristics of δ-FAPbI3/ALD-SnO2 demonstrate exceptional linearity and potentiation/depression performance, resembling an artificial synapse for neuromorphic computing. The nonlinearity of long-term potentiation and long-term depression is notably decreased from 12.26 to 0.60 and from −8.79 to −3.47, respectively. Moreover, the δ-FAPbI3/ALD-SnO2 bilayer achieves a recognition rate of ≤94.04% based on the modified National Institute of Standards and Technology database (MNIST), establishing its potential in an efficient artificial synapse

Effect of Fluorine Substitution in a Hole Dopant on the Photovoltaic Performance of Perovskite Solar Cells

Most of the high-efficiency perovskite solar cells (PSCs) are based on the doped spiro-MeOTAD as a hole-transporting layer. Lithium sulfonyl imides with the general chemical formula of LiN­(SO2CnF2n+1)2 (n = 0, 1, and 2 for LiFSI, LiTFSI, and LiPFSI, respectively) are candidates for dopants. Although LiTFSI is generally used, it is argued that the power conversion efficiency (PCE) is better for LiPFSI than for LiTFSI due to higher fluorine substitution. In this report, we investigate the effect of the amount of fluorine substitution on photovoltaic performance. Four different researchers fabricated independently PSCs, which reveals that the PCE is highest in the following order, LiTFSI ≈ LiFSI > LiPFSI. The relatively lower performance for LiPFSI is attributed to the interfacial problem and aggregate formation leading to a nonuniform film, which is related to the hydrophobicity and lipophobicity increased by perfluorination. LiFSI however has poor moisture stability due to being less hydrophobic. We draw the conclusion that LiTFSI is a suitable dopant among the studied candidates in terms of both efficiency and stability due to moderate hydrophobicity

High Efficiency Solid-State Sensitized Solar Cell-Based on Submicrometer Rutile TiO₂ Nanorod and CH₃NH₃PbI₃ Perovskite Sensitizer

We report a highly efficient solar cell based on a submicrometer (∼0.6 μm) rutile TiO₂ nanorod sensitized with CH₃NH₃PbI₃ perovskite nanodots. Rutile nanorods were grown hydrothermally and their lengths were varied through the control of the reaction time. Infiltration of spiro-MeOTAD hole transport material into the perovskite-sensitized nanorod films demonstrated photocurrent density of 15.6 mA/cm², voltage of 955 mV, and fill factor of 0.63, leading to a power conversion efficiency (PCE) of 9.4% under the simulated AM 1.5G one sun illumination. Photovoltaic performance was significantly dependent on the length of the nanorods, where both photocurrent and voltage decreased with increasing nanorod lengths. A continuous drop of voltage with increasing nanorod length correlated with charge generation efficiency rather than recombination kinetics with impedance spectroscopic characterization displaying similar recombination regardless of the nanorod length

Defect Passivation of Low-Temperature-Sputtered Tin Oxide Electron Transport Layers through Magnesium Doping for Perovskite Solar Cells

The optimal choice of electron transporting materials is of vital importance in improving the efficiency and reducing the cost of perovskite solar cells (PSCs) as electron transport layers (ETLs) play a key role in charge extraction and transfer. Despite SnO2 being a commonly used ETL, magnetron-sputtered SnO2 continues to be constrained by oxygen vacancy (VO)-related point defects, which result in severe interface charge recombination, thereby limiting the open-circuit voltage and fill factor of PSCs using magnetron-sputtered SnO2 ETLs. Herein, a doping strategy was adopted to suppress the defect density in magnetron-sputtered SnO2, in which Mg:SnO2 (MTO) was prepared by magnetron co-sputtering of MgO and SnO2 at room temperature. After Mg doping, the VO defects were passivated, the density of the trap states in the SnO2 ETL was reduced, and the energy level alignment between the ETL and perovskite layer was optimized. As a result, the undesired charge recombination was effectively suppressed, thus leading to an approximately 8.7% increase in the average device efficiency and approximately 11% increase in the stabilized power output. The best-performing device achieved an efficiency of 19.55%, therefore indicating the high potential of the magnetron-sputtered Mg:SnO2 ETL toward the commercialization of PSCs