The interfacial mutual solubility can result in a random distribution of donor and acceptor materials during the spin-coating step in the fabrication of planar heterojunction (PHJ) near-infrared (NIR) organic phototransistors. In this case, deep trap states are induced by acceptors, accelerating electron-hole recombination, ultimately impairing the photoresponsivity of the phototransistor. To solve this issue, a controllable mutual dissolution layer (formed by co-solvent treatment) combined with a diffusion interface layer (formed by the solvent vapor annealing (SVA) method) was introduced to achieve a more ordered arrangement of donors and acceptors, thereby enhancing the electrical performance of PHJ-based NIR phototransistors. Compared with a PDPP3T/PC61BM CF device, a PDPP3T/PC61BM THF : CF (SVA) device in which the PC61BM layer is spin-coated with THF : CF co-solvent and with SVA exhibited a significant performance improvement. The device exhibits a reduction in V o from 23 V to 4 V, a 5-fold increase in ΔV th (up to ∼26.0 V), a 30-fold enhancement in photocurrent (ΔI ph ∼64.6 μA), and a dramatic rise in photosensitivity (I ph/I dark) from 205 to 5.6 × 108 (850 nm @ 0.1 mW cm-2).

A large potential barrier is formed by introducing higher-LUMO-level acceptors into the bulk heterojunction, which ensures that the electrons recombine with holes instead of exhibiting transmission, decreasing the dark current ~3 orders of magnitude.

Thermal barrier coatings (TBCs) in gas turbine engines are used in expressly harsh environments; thus, assessing TBC integrity status is critical for safety and reliability. However, traditional periodic maintenance involves visual inspections of the TBCs, requiring the gas turbine to be decommissioned and partially dismantled. Most importantly, tiny defects or internal damages that easily cause coating failure cannot be identified. In this work, a new nondestructive evaluation (NDE) technique of TBCs based on quantum dot (QD) anion exchange is first explored internationally. By exchanging anions between the Cl ions and the CsPbBr 3 QDs, the degrees of salt corrosion of the TBCs are evaluated. The resultant NDE technique shows that the colour of the TBCs obviously changes from green to blue, accompanied by a large blueshift (∼ 100 nm) of the photoluminescence (PL) peak position. In addition, the relationship between the PL peak position and coating thermophysical properties indicates that the precision of this NDE technique may easily identify the µm-level of the thermal growth oxide (TGO) changes inside the TBCs.

全无机钙钛矿因具有适用于光电器件的带隙和优异的热稳定性与光学性能而受到人们的大量关注.然而,钙钛矿薄膜的低质量和高陷阱密度,以及CsPbI2Br钙钛矿太阳能电池(PSCs)的低转换效率(PCE)和较大的能量损失,限制了这类器件的应用.首先,文章综述了全无机钙钛矿材料的晶体结构和稳定性,介绍了全无机铯铅卤化钙钛矿CsPbIxBr3-x(如CsPbI2Br)的研究现状和发展前景,阐释了提高光电转换效率的几种常见途径(如界面工程、前驱体工程、表面钝化技术等).其次,实验研究发现,在CsPbI2Br基钙钛矿溶液中加入添加剂可使钙钛矿层更加致密,能提升器件稳定性.综述与实验研究为高性能CsPbI2Br器件制造提供了新的见解.

In near-infrared (NIR) polymer phototransistors, the photoresponse is proportional to the turn-on voltage shift (ΔVth). Due to the narrow band gap of NIR polymers, the ΔVth value is usually small. However, the use of a single bulk heterojunction (BHJ) layer has a minimal effect on increasing the value of ΔVth. This is because doping with high concentrations of acceptors results in strong current traps and accelerates electron/hole recombination. In this work, a new strategy is proposed to control the recombination of electrons/holes. By doping an insulating medium made of polystyrene (PS) into BHJs, PC61BM:PS:PDPP3T-based ternary NIR phototransistors with high acceptor concentrations were prepared by using a one-step film transfer method (FTM). Compared with a PC61BM:PDPP3T-based binary device (1:1), a ternary device (1:1:1) exhibited a significant performance improvement. The ΔVth value (∼29.5 ± 1.0 V) increased by approximately 4-fold, the Iph/Idark (∼4.4 × 106) increased by a factor of 3000 to 4000-fold, and the dark current decreased by 2-3 orders of magnitude (@ Vg = 0 V). Additionally, the ternary devices demonstrated excellent performance across a wide ternary ratio range (1:1:1 to 4:2:1).

本文利用热注入法制备了蓝光CsPbBr3 钙钛矿量子点,研究探索了反应温度、钕掺杂和HBr刻蚀对量子点光致发光(photoluminescence,PL)性能的影响.研究发现,随着反应温度的升高,量子点的PL峰值波长发生红移,因而可合理利用反应温度调控CsPbBr3 量子点的PL峰值波长.利用HBr对量子点进行蚀刻,刻蚀后的量子点,PL峰值波长发生蓝移,半峰宽变窄.钕掺杂的CsPbBr3 量子点PL峰值波长发生蓝移,时间稳定性、热稳定性、水稳定性都得到了提升.

Taking the course of photoelectric film and vacuum technology as an example, this paper discusses the teaching reform based on interactive mode between course teaching and scientific research from three aspects: teaching content, classroom teaching method, examination and evaluation. The practice results showed that the students who participated in the scientific research group were significantly higher than the average level of the class in terms of classroom performance, scientific research and innovation ability. Besides, it is easier to get excellent results in typical research and competitions such as innovation and entrepreneurship training, “Internet+”competition.

The narrow bandgap of the low-energy near-infrared (NIR) polymer would lead to overlap between adjacent energy levels, which is a major barrier to the preparation of Vis-NIR polymer bulk heterojunction (BHJ) photodetectors with small responsivity and photocurrent. In this study, a high-performance lateral inorganic-organic hybrid photodetector was constructed to eliminate this barrier by combining GaN nanowires (GaN-NWs) with PDPP3T:PC61BM-based BHJ. In stage one, high-quality GaN-NWs were synthesized by the catalyst-free CVD method. The mechanism for controlling GaN-NWs morphology by adjusting the NH3 flow rate was revealed. In stage two, the GaN-NWs with large electron mobility were used to accelerate the transfer of photogenerated carriers in the BHJ layer. Finally, compared with the BHJ device, the BHJ/GaN device demonstrated obvious improvements in responsivity and photocurrent at the wavelength between 400 and 1000 nm. The responsivity and photocurrent increased over 20-fold at the NIR band of 800–900 nm. Besides, owing to the energy level gradient effect, the BHJ/GaN device has a response speed of 7.8/<5.0 ms, which increases over three orders of magnitude than that of the GaN-NWs-based device (tr/tf: 7.1/10.9 s). Therefore, the novel device structure proposed in this work holds great potential for preparing high-performance Vis-NIR photodetectors.

The narrow bandgap of near-infrared (NIR) polymers is a major barrier to improving the performance of NIR phototransistors. The existing technique for overcoming this barrier is to construct a bilayer device (channel layer/bulk heterojunction (BHJ) layer). However, acceptor phases of the BHJ dissolve into the channel layer and are randomly distributed by the spin-coating method, resulting in turn-on voltages (Vo) and off-state dark currents remaining at a high level. In this work, a diffusion interface layer is formed between the channel layer and BHJ layer after treating the film transfer method (FTM)-based NIR phototransistors with solvent vapor annealing (SVA). The newly formed diffusion interface layer makes it possible to control the acceptor phase distribution. The performance of the FTM-based device improves after SVA. Vo decreases from 26 V to zero, and the dark currents decrease by one order of magnitude. The photosensitivity (Iph/Idark) increases from 22 to 1.7 × 107.

本文从谐振子出发,考虑电偶极子-电偶极子的相互作用,采用正则变换,消除交叉项,使之成为两个独立的谐振子,进一步算出两个新谐振子的角频率,还能算出体系的基态能量,并解释范德瓦尔斯相互作用的分离相关性.再用概率论的知识探讨了波函数,解释了存在范德瓦尔斯相互作用而导致能量下降的原因,并计算了两个谐振子的条件概率.

In this paper, we give the normal and abnormal Bloch states at the Brillouin zone edge to a spin–orbit (SO) coupled Bose–Einstein condensate (BEC) with a high-frequency driving and confined in a periodic lattice. The generation of the spatiotemporal Bloch states and the associated the population transfer and the superflow are studied. We find that Rabi coupling strength can enhance or reduce the population transfer between two BEC components for the obtained Bloch states. In addition, we can realize the transition between superfluid state and critical balance state by adjusting system parameters, which could be helpful to the quantum transport of the SO coupled cold-atom system.

本文研究了电磁波在一维磁各向异性周期介质传播,受电场、磁场等多个自由度调制下的传输问题,利用麦克斯韦方程组、连续性边界条件以及传输矩阵、行列式等知识,得到了一个4×4传输矩阵.这个传输矩阵能够描述电磁波在一维多自由度磁各向异性周期结构传播的基本性质.我们希望这样的求解过程会有助于加深同学们对平面电磁波的理解,并且为了以后的学习和研究夯实基础.

The aggregation behavior of polymers can ultimately have a significant impact on the performance of polymer photodetectors depends mainly on the main solvent, solvent additive, thermal annealing treatment, and so on. In this work, a phase control behavior of lateral polymer photodetectors (L-PPDs) is realized by changing the acceptor concentration or introducing 1,8-diiodooctane (DIO) in strong aggregation of bulk heterojunction (BHJ) films, which can effectively regulate the minority carriers trapping under high PC61BM ratio. Additionally the responsivity (R), gain (G) and specific detectivity (D*) value of the L-PPDs can reach 94.4 A W-1, 289.7, and 1.33 x 10(14) Jones under 0.0031 mW cm(-2) @405 nm, respectively. The structure of the L-PPDs is optimized as quartz/ PMMA (30 nm)/ PffBT4T-2OD:PC61BM (D/A ratio = 1:1.2)/ Ag-Ag electrodes. Furthermore, the phase separation of the thin films is promoted by introducing 3% DIO, resulting in a clear increase of response speed (fall time is about tenfold faster than that of the control device), and an improved switching performance about 60-fold higher under strong light (10.42 mW cm(-2)). This research represents an important step forward in the fabrication of high-performance polymer photodetectors, which show promising application potential.

A continuous transmission channel of minority carrier forms under high concentration acceptor doping, leading to poor phototransistor performance. However, the minority carrier cannot move under low acceptor doping, promoting the device performance.

The slow response speed and instability of the lateral photodetectors (L-PDs), often caused by the persistence of the excess minority carriers in the long channel after the termination of the illumination (called Persistent Photoconductivity effects) are the main factors that hinder the practical application of this type of device. In this research, two types of ZnO with different work functions, including ZnO nanoparticles (ZnO-NPs) doped in bulk heterojunction (BHJ) and thermal annealed ZnO nanocrystalline film (ZnO-NF), are incorporated into the L-PDs to construct an energy gradient, which could facilitate the quick transfer of the minority carriers and restrict their release into the active layer. The structure of L-PDs are optimized as quartz/ZnO-NF/PffBT4T-2OD:PC61BM:ZnONPs (component ratio = 5:6:1)/Au-Au electrodes. Compared with the control device, the test results show that the optimized L-PDs exhibit higher stability with much lower fall time (3.7 ms, boosted 200-fold) and gentler rise slope of dark current versus time (K-dark) (8.3 x 10(-6) nA/s, reduced four orders of magnitude). Meanwhile, the very low dark current (<5.5 x 10(-13) A) of L-PDs allows the specific detectivity (D*) to be maintained at a high level (1.1 x 10(15) -6.7 x 10(15) Jones) with a wide wavelength range (from 410 to 690 nm) under 4.4 mu W/cm(2). Therefore, the gradient trapping strategy shows promising application potential.

In this work, a new strategy is proposed to improve the performance of poly (3-hexylthiophene-2,5-diyl) (P3HT) based organic field-effect transistor (OFET). The high orientation of P3HT chain is obtained via utilizing precipitation characteristics of P3HT in volatile CH2Cl2 with the temperature decrease of solution in the hot spincoating process. Meanwhile, a small amount of 1,2-dichlombenzene (ODCB) with high boiling point is introduced into CH2Cl2 to make the inner part of the film stay in liquid state for a long time, and prolong the self-organization time of P3HT chain. Compared with control device prepared in pure CH2Cl2, the mobility of optimized device obtained by using blended solvent increases about 20-fold, the on/off ratio enhances about three orders of magnitude, and the operation time window of spin-coating up to 30 min (control device < 30 s). With this new strategy, the film quality can be easily controlled, which provides a new method for preparation of high-performance polymer optoelectmnic devices.

针对新工科建设的要求,对工科物理教学进行改革,从教学内容优化、"双师"型教学团队建设、多样化教学平台使用、基于创新能力提升的课堂教学方式改革、多元化和过程化的考核评价方式等五个方面进行教学改革研究.结果表明,教学改革提升了学生的工科意识,有效地提高了大学物理教学质量.

采用有限元方法,通过商业求解软件MAXWELL,解决电容触摸屏潜在的静电场问题,对触摸屏面板布局进行了描述,主要性能指标进行了确定.利用仿真模拟的方法,研究电容触摸屏具体图案对电容屏触摸灵敏度的影响.对于具体菱形挖空图案,通过软性电路板材料(FPC)屏对氧化铟锡材料(ITO)屏进行了模拟仿真计算和实验测试,并且进行数据比较,验证了此仿真方案可以测试不同电容屏图案的灵敏度,不需要生产出ITO真屏对灵敏度进行测试比较,大大节省了触摸屏优化设计的成本.

为帮助地方院校医学专业大一新生加深对微积分的理解,以刚体球转动惯量为例,在利用微积分解决物理问题时,阐明了“最大程度利用物理量的对称性将使计算最简”、微积分中的所谓“近似计算”在极限条件下是精确的等问题.

Chemical immobilization using phosphorous-containing materials cause heavy metals in soils to shift from forms with high availability to the most strongly bound fractions.Phosphate-containing materials utilization was proposed as the best management practice for remediation of heavy metals polluted soils for its easy operation,efficiency and low-cost.Current studies involving in-situ remediation of heavy metals polluted soils using phosphorous-containing materials were reviewed.The types of phosphorous-containing materials,the mechanism,influential factors and limitation of the remediation using phosphorous-containing materials were discussed in detail.Meanwhile,the research tendency and development prospects of the remediation technologies using phosphorous-containing materials were forecasted in dealing with heavy metals polluted soils.