The perovskite is a class of material with crystalline structure similar to CaTiO3. In recent years, the organic-inorganic hybrid metallic halide perovskite has been widely investigated as a promising material for a new generation photovoltaic device, whose power conversion efficiency (PCE) record reaches 22.7%. One of its underlying morphological characteristics is the twin domain within those sub-micron sized crystal grains in perovskite thin films. This is important for discussion since it could be the key for understanding the fundamental mechanism of the device's high performance, such as long diffusion distance and low recombination rate. This review aims to summarize studies on twin domains in perovskite thin films, in order to figure out its importance, guide the current studies on mechanism, and design new devices. Firstly, we introduce the research history and characteristics of widely known twin domains in inorganic perovskite BaTiO3. We then focus on the impact of the domain structure emerging in hybrid metallic halide perovskite thin films, including the observation and discussion on ferroelectricity/ferroelasity. The theoretical analysis is also presented in this review. Finally, we present a spectroscopic method, which can reveal the generality of twin domains within perovskite thin films. We anticipate that this summary on the structural and physical properties of organometallic halide perovskite will help to understand and improve the high-performance of photovoltaic devices.
Two novel small molecules DTRDTQX and DTIDTQX, based on ditolylaminothienyl group as donor moiety and quinoxaline as middle acceptor moiety with different terminal acceptor groups were synthesized and characterized in this work. In order to study the photovoltaic properties of DTRDTQX and DTIDTQX, bulk-heterojunction solar cells with the configuration of FTO/c-TiO2/DTRDTQX(or DTIDTQX):C-70/MoO3/Ag were fabricated, in which DTRDTQX and DTIDTQX acted as the donors and neat C-70 as the acceptor. When the weight ratio of DTRDTQX :C-70 reached 1:2 and the active layer was annealed at 100 degrees C, the optimal device was realized with the power conversion efficiency (PCE) of 1.44%. As to DTIDTQX :C-70-based devices, the highest PCE of 1.70% was achieved with the optimal blend ratio ( DTIDTQX :C-70 = 1:2) and 100 degrees C thermal annealing treatment. All the experimental data indicated that DTRDTQX and DTIDTQX could be employed as potential donor candidates for organic solar cell applications.
Linear-optical logic gates have the potential to be the bases of the next-generation information technology (IT) because of the low power consumption and rapid response. This study proposes a general theoretical model to obtain the optimal solutions for linear-optical logic gates. All common logic gates (AND, OR, NOT, NAND, NOR, XOR, and XNOR) are experimentally demonstrated with one single sample structure based on ultracompact plasmonic waveguides. The measured intensity contrast ratio between the output-logic “1” and “0” states reaches 28 dB for the OR gate and 9.4 dB for the AND gate, thereby approaching the theoretical maximum of infinity and 9.5 dB, respectively. The proposed logic gates provide uniform output intensities for identical output logics when the input logics are different. The measured intensity discrepancies are below 1% for the three output-logic “1” states of the OR gate and the three output-logic “0” states of the AND gate. This phenomenon is favored in practical applications and the cascading of logic gates. The proposed universal linear-optical logic gate with maximal intensity contrast ratios may find important future applications in the field of IT.
Liu Y-H, Liu C, Bierig R. User interactions with search systems, in Proceedings of the 2018 ACM SIGIR International Conference on Theory of Information Retrieval.; 2018:3–4.
INTRODUCTION: Data based on electronic health records (EHRs) are rich with individual-level longitudinal measurement information and are becoming an increasingly common data source for clinical risk prediction worldwide. However, few EHR-based cohort studies are available in China. Harnessing EHRs for research requires a full understanding of data linkages, management, and data quality in large data sets, which presents unique analytical opportunities and challenges. The purpose of this study is to provide a framework to establish a uniquely integrated EHR database in China for scientific research. METHODS AND ANALYSIS: The CHinese Electronic health Records Research in Yinzhou (CHERRY) Study will extract individual participant data within the regional health information system of an eastern coastal area of China to establish a longitudinal population-based ambispective cohort study for cardiovascular care and outcomes research. A total of 1 053 565 Chinese adults aged over 18 years were registered in the health information system in 2009, and there were 23 394 deaths from 1 January 2009 to 31 December 2015. The study will include information from multiple epidemiological surveys; EHRs for chronic disease management; and health administrative, clinical, laboratory, drug and electronic medical record (EMR) databases. Follow-up of fatal and non-fatal clinical events is achieved through records linkage to the regional system of disease surveillance, chronic disease management and EMRs (based on diagnostic codes from the International Classification of Diseases, tenth revision). The CHERRY Study will provide a unique platform and serve as a valuable big data resource for cardiovascular risk prediction and population management, for primary and secondary prevention of cardiovascular events in China. ETHICS AND DISSEMINATION: The CHERRY Study was approved by the Peking University Institutional Review Board (IRB00001052-16011) in April 2016. Results of the study will be disseminated through published journal articles, conferences and seminar presentations, and on the study website (http://www.cherry-study.org).
