Silicon-organic heterojunction solar cells suffer from a noticeable weakness of inefficient rear contact. To improve this rear contact quality, here, two solution-processed organic n-type donor-acceptor naphthalene diimide (NDI)-based conjugated polymers of N2200 and fluorinated analogue F-N2200 are explored to reduce the contact resistance as well as to passivate the Si surface. Both N2200 and F-N2200 exhibit high electron mobility due to their planar structure and strong intermolecular stacking, thus allowing them to act as excellent transporting layers. Preferential orientation of the polymers leads to reduce contact resistance between Si and cathode aluminum, which can enhance electron extraction. More importantly, the substitution of fluorine atoms for hydrogen atoms within the conjugated polymer can strengthen the intermolecular stacking and improve the polymer-Si electronic contact due to the existence of F···H interactions. The power conversion efficiencies of Si-PEDOT:PSS solar cells increased from 12.6 to 14.5% as a consequence of incorporating the F-N2200 polymer interlayers. Subsequently, in-depth density functional theory simulations confirm that the polymer orientation plays a critical role on the polymer-Si contact quality. The success of NDI-based polymers indicates that planar conjugated polymer with a preferred orientation could be useful in developing high-performance solution-processed Si-organic heterojunction photovoltaic devices.
Han Yujie Liu Yu-Qiang Jianyu Yuan Huilong Dong Youyong Li 马万里 李述汤 Sun Baoquan
ACS Nano
2017
An integrated self-charging power unit, combining a hybrid silicon nanowire/polymer heterojunction solar cell with a polypyrrole-based supercapacitor, has been demonstrated to simultaneously harvest solar energy and store it. By efficiency enhancement of the hybrid nanowire solar cells and a dual-functional titanium film serving as conjunct electrode of the solar cell and supercapacitor, the integrated system is able to yield a total photoelectric conversion to storage efficiency of 10.5%, which is the record value in all the integrated solar energy conversion and storage system. This system may not only serve as a buffer that diminishes the solar power fluctuations from light intensity, but also pave its way toward cost-effective high efficiency self-charging power unit. Finally, an integrated device based on ultrathin Si substrate is demonstrated to expand its feasibility and potential application in flexible energy conversion and storage devices.
Liu Ruiyuan Jie Wang Sun Teng Wang Mingjun Wu Changsheng Zou Haiyang Song Tao 张晓宏 李述汤 王中林 Sun Baoquan
Nano Letters
2017
Small molecules play critical roles in life science, yet their facile detection and imaging in physiological or pathological settings remain a challenge. Matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) is a powerful tool for molecular analysis. However, conventional organic matrices (CHCA, DHB, etc.) used in assisting analyte ionization suffer from intensive background noise in the mass region below m/z 700, which hinders MALDI MS applications for small-molecule detection. Here, we report that a hydroxyl-group-dominated graphite dot (GD) matrix overcomes limitations of conventional matrices and allows MALDI MS to be used in fast and high-throughput analysis of small biomolecules. GDs exhibit extremely low background noise and ultrahigh sensitivity (with limit of detection <1 fmol) in MALDI MS. This approach allows identification of complex oligosaccharides, detection of low-molecular-weight components in traditional Chinese herbs, and facile analysis of puerarin and its metabolites in serum without purification. Moreover, we show that the GDs provide an effective matrix for the direct imaging or spatiotemporal mapping of small molecules and their metabolites (m/z < 700) simultaneously at the suborgan tissue level. Density functional theory calculations further provide the mechanistic basis of GDs as an effective MALDI matrix in both the positive-ion and negative-ion modes. Collectively, our work uncovered a useful matrix which reshapes MALDI MS technology for a wide range of applications in biology and medicine.
Rui Shi Dai Xing Weifeng Li Lu Fang Liu Yang Qu Hui-Hua Li Hao Chen Qiongyang Tian He Wu Enhui Wang Yong Ruhong Zhou 李述汤 Yeshayahu Lifshitz 康振辉 Jian Liu
ACS Nano
2017
Electrochemical reduction of COrepresents a possible solution for transforming atmospheric COto value-added chemicals such as CO or hydrocarbons, but so far it has been hampered by the lack of suitable electrocatalysts. In this work, we design a type of organic-inorganic hybrid material by template-directed polymerization of cobalt phthalocyanine on carbon nanotubes for a high-performance COreduction reaction. Compared with molecular phthalocyanines, the polymeric form of phthalocyanines supported on the conductive scaffold exhibits an enlarged electrochemically active surface area and improved physical and chemical robustness. Experimental results show that our hybrid electrocatalyst can selectively reduce COto CO with a large faradic efficiency (∼90%), exceptional turnover frequency (4,900 hrat η = 0.5 V), and excellent long-term durability. These metrics are superior to those of most of its organic or inorganic competitors. Its high electrocatalytic activity is also supported by density functional theory calculations. Growing worldwide consumption of fossil fuels has resulted in an increasing concentration of atmospheric COand profound climate changes. Electrocatalytic COreduction to liquid or gaseous fuels is ideal for high-density renewable energy storage and could represent an attractive prospect for COcapture. However, it still remains a grand challenge to develop efficient and stable electrocatalysts for COreduction. Most current research attention has focused on inorganic candidates such as Au, Ag, and Cu, but the potential of organic phthalocyanines or porphyrins has not been adequately explored. These molecular catalysts generally suffer from large overpotentials, insufficient faradic efficiency, and poor durability. In this work, we report a hybrid material consisting of a carbon nanotube core and cobalt polyphthalocyanine sheath as a highly efficient and stable catalyst for the selective conversion of COto CO with a performance unmatched by those of other organic COreduction electrocatalysts. Han et al. have prepared a type of organic-inorganic hybrid material by template-directed polymerization of cobalt phthalocyanine on carbon nanotubes for a selective COreduction reaction to CO with a large faradic efficiency, exceptional turnover frequency, and excellent long-term durability.
Na Han Yu olivia Wang Lu Ma Wen Jianguo Li Jing Zheng Hechuang Nie Kaiqi Wang Xinxia Feipeng Zhao Yafei Li Jian Fan Zhong Jun Tianpin Wu Dean Miller Jun Lu 李述汤 Yanguang Li
Chem
2017
Syngas, a CO and Hmixture mostly generated from non-renewable fossil fuels, is an essential feedstock for production of liquid fuels. Electrochemical reduction of COand H/HO is an alternative renewable route to produce syngas. Here we introduce the concept of coupling a hydrogen evolution reaction (HER) catalyst with a CDots/CNcomposite (a COreduction catalyst) to achieve a cheap, stable, selective and efficient route for tunable syngas production. CoO, MoS, Au and Pt serve as the HER component. The CoO-CDots-CNelectrocatalyst is found to be the most efficient among the combinations studied. The H/CO ratio of the produced syngas is tunable from 0.07:1 to 4:1 by controlling the potential. This catalyst is highly stable for syngas generation (over 100 h) with no other products besides CO and H. Insight into the mechanisms balancing between COreduction and Hevolution when applying the HER-CDots-CNcatalyst concept is provided.
Sijie Guo Zhao Siqi Wu Hao Li Zhou Yunjie Zhu Cheng Nianjun Yang Xin Jiang Gao Jin Bai Liang 刘阳 Yeshayahu Lifshitz 李述汤 康振辉
Nature Communications
2017
The elongation of free-standing one-dimensional (1D) functional nanostructures into lengths above the millimeter range has brought new practical applications as they combine the remarkable properties of nanostructured materials with macroscopic lengths. However, it remains a big challenge to prepare 1D silicon nanostructures, one of the most important 1D nanostructures, with lengths above the millimeter range. Here we report the unprecedented preparation of ultralong single-crystalline Si nanowires with length up to 2 cm, which can function as the smallest active material to facilitate the miniaturization of macroscopic devices. These ultralong Si nanowires with augmented flexibility are of emerging interest for flexible electronics. We also demonstrate the first single-nanowire-based wearable joint motion sensor with superior performance to reported systems, which just represents one example of novel devices that can be built from these nanowires. The preparation of ultralong Si nanowires will stimulate the fabrication and miniaturization of electric, optical, medical, and mechanical devices to impact the semiconductor industry and our daily life in the near future.
Zhang Bingchang Wang Hui Le He Zheng Cai-Jun Jie Jian-Sheng Yeshayahu Lifshitz 李述汤 张晓宏
Nano Letters
2017
Liangsheng Liao 李述汤
Nature Reviews Materials
2016
We demonstrate that charge carrier diffusion lengths of two classes of perovskites, CHNHPbICland CHNHPbI, are both highly sensitive to film processing conditions and optimal processing procedures are critical to preserving the long carrier diffusion lengths of the perovskite films. This understanding, together with the improved cathode interface using bilayer-structured electron transporting interlayers of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)/ZnO, leads to the successful fabrication of highly efficient, stable and reproducible planar heterojunction CHNHPbIClsolar cells with impressive power-conversion efficiencies (PCEs) up to 15.9%. A 1-square-centimeter device yielding a PCE of 12.3% has been realized, demonstrating that this simple planar structure is promising for large-area devices.[Figure not available: see fulltext.].
Sai Bai Zhongwei Wu Wu Xiaojing Yizheng Jin 赵铌 Chen Zhihui Mei Qingqing Wang Xin 叶志镇 Song Tao Liu Ruiyuan 李述汤 Sun Baoquan
Nano Research
2014
The authors show that II-VI nanoribbons are capable of room-temperature lasing covering the complete spectral range from near infrared (NIR) to ultraviolet (UV). This is accomplished by simply using nanoribbons of two ternary compositions, namely, Cd SX Se1-X and ZnY Cd1-Y S. Under optical pumping, Cd SX Se1-X nanoribbons lase from NIR (710 nm) to green (510 nm) as X changes from 0 to 1, while ZnY Cd1-Y S nanoribbons lase from green (510 nm) to UV (340 nm) as Y varies from 0 to 1. Furthermore, lasing control shows fine-tuning via composition changes that overlap thermally induced tuning. This demonstrates that II-VI materials can enable lasing at any selected wavelength between 710 and 340 nm with continuous tuning capabilities. © 2007 American Institute of Physics.
Juan antonio Zapien Yingkai Liu Yueyue Shan Tang Hao Lee C. 李述汤
Applied Physics Letters
2007
Copper-doped CdZnS (x∼0.16) nanoribbons were prepared by controlled thermal evaporation of CdS, ZnS, and CuS powders onto Au-coated silicon substrates. The nanoribbons had a hexagonal wurtzite structure, and lengths of several tens to hundreds of micrometres, widths of 0.6-15νm, and thicknesses of 30-60nm. Cu doping and incorporation into the CdZnS lattice were identified and characterized by low-temperature photoluminescence (PL) and photoconductivity measurements. Temperature-dependent PL measurement showed that the PL spectra of both Cu-doped and undoped CdZnS nanoribbons have two emission peaks at 2.571 and 2.09eV, which are assigned to band edge emission and deep trap levels, respectively. In addition, the Cu-doped nanoribbons present two extra peaks at 2.448 and 2.41eV, which are attributed to delocalized and localized donor and acceptor states in the band gap of CdZnS resulting from Cu incorporation. Photoconductivity results showed the nanoribbons can be reversibly switched between low and high conductivity under pulsed illumination. The Cu-doped CdZnS nanoribbons showed four orders of magnitude larger photocurrent than the undoped ones. The current jumped from ∼2 × 10 to ∼5.7 × 10A upon white light illumination with a power density of ∼9mWcm. The present CdZnS:Cu nanoribbons may find applications in opto-electronic devices, such as solar cells, photoconductors, and chemical sensors. © IOP Publishing Ltd.
Lui Tsz-Yan Juan antonio Zapien Tang Hao Ma Dorothy Duo Duo Yingkai Liu Lee C. 李述汤 Shi 徐士杰
Nanotechnology
2006