科研成果

The near-retirement households among all working-age groups in the United States experienced larger drops in consumption and greater increases in labor force participation during the financial crisis of 2007-2009. Also, the retirement probability for near-retirement homeowners (but not for renters) decreases more in those areas where housing prices also decline more. This paper argues that the wealth effect of housing prices on retirement can account for those issues. It creates an incomplete-market life-cycle partial-equilibrium model with risky housing assets and endogenous retirement and verifies that the joint response of retirement and non-durable consumption implied by the structural model is consistent with the empirical findings using data from the Health and Retirement Study 1992-2012. It then shows that, after an unexpected 28 percent housing price decline, near-retirement homeowners ages 55-64 will reduce their non-durable consumption by 4.6 percent and increase their labor force participation by 1 percentage point immediately and delay their retirement by 2.8 months in the long run. The model also quantifies endogenous retirement as self-insurance for elderly homeowners against housing price risk. (Copyright: Elsevier)

Here we report, for the first time, the growth of single-crystalline mesoporous MOFs with well-controlled orientation on the surface of gold nanorods. Importantly, it showed that trace amounts of water could induce the formation of MOFs of different phases and shapes, which was critical for the synthesis of such mesoporous heterostructures.

Here we report the measurement results of nitrous acid (HONO) and a suite of relevant parameters on the NCAR C-130 research aircraft in the southeastern US during the NOMADSS 2013 summer field study. The daytime HONO concentration ranged from low parts per trillion by volume (pptv) in the free troposphere (FT) to mostly within 5–15pptv in the background planetary boundary layer (PBL). There was no discernible vertical HONO gradient above the lower flight altitude of 300m in the PBL, and the transport of ground surface HONO was not found to be a significant contributor to the tropospheric HONO budget. The total in situ HONO source mean (±1SD) was calculated as 53 (±21)pptvh−1 during the day. The upper-limit contribution from NOx-related reactions was 10 (±5)pptvh−1, and the contribution from photolysis of particulate nitrate (pNO3) was 38 (±23)pptvh−1, based on the measured pNO3 concentrations and the median pNO3 photolysis rate constant of 2.0 × 10−4s−1 determined in the laboratory using ambient aerosol samples. The photolysis of HONO contributed to less than 10% of the primary OH source. However, a recycling NOx source via pNO3 photolysis was equivalent to  ∼ 2.3 × 10−6molm−2h−1 in the air column within the PBL, a considerable supplementary NOx source in the low-NOx background area. Up to several tens of parts per trillion by volume of HONO were observed in power plant and urban plumes during the day, mostly produced in situ from precursors including NOx and pNO3. Finally, there was no observable accumulation of HONO in the nocturnal residual layer and the nocturnal FT in the background southeastern US, with an increase in the HONO∕NOx ratio of  ≤ 3 × 10−4h−1 after sunset.

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.