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Hot-exciton effects on exciton diffusion and circular polarization dynamics in a single PbI_(2)nanoflake

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Science China(Technological Sciences) 2024年第1期67卷 83-90页

作者： XU ChenYu WANG Lei CUI Lin GAO BingRong WANG HaiYu State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

As one of the emerging two-dimensional lead halide materials,lead iodide(PbI_(2))nanosheets have proven to possess strong application potential in the fields of high-energy radiation detection and highly efficient perovskite solar cells.However,the underlying photophysical properties such as hot-exciton-related carrier dynamics remain unclear for PbI_(2)nanosheets.Here,we report the exciton dynamics of a single PbI_(2)nanoflake prepared by an aqueous solution method.Through a three-dimensional(3D)diffusion model,we obtain the exciton annihilation radius and diffusion coefficient of a single PbI_(2)nanoflake under nonresonant and resonant excitation conditions of band-edge exciton state.As initial exciton densities increase,we find the carrier recombination mechanism for a single PbI_(2)nanoflake gradually changes from exciton-exciton annihilation to free-carrier recombination.Finally,we reveal the room-temperature circular polarization of a single PbI_(2)nanoflake is due to free-carrier recombination with a band-edge exciton dissociation time of~120 fs under the resonant excitation condition.

关键词： single PbI_(2)nanoflake exciton diffusion room-temperature circular polarization ultrafast spectroscopy

Mode-insensitive and mode-selective optical switch based on asymmetric Y-junctions and MMI couplers

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Photonics Research 2024年第3期12卷 423-430页

作者： SHIJIE SUN QIDONG YU YUANHUA CHE TIANHANG LIAN YUHANG XIE DAMING ZHANG XIBIN WANG State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

Driven by the large volume demands of data in transmission systems,the number of spatial modes supported by mode-division multiplexing(MDM)systems is being increased to take full advantage of the parallelism of the signals in different spatial modes.As a key element for photonic integrated circuits,the multimode waveguide optical switch(MWOS)is playing an important role for data exchange and signal switching.However,the function of the traditional MWOS is simple,which could only implement the mode-insensitive or mode-selective switching function;it is also difficult to scale to accommodate more spatial modes because of the limitation of the device structure.Therefore,it is still challenging to realize a multifunctional and scalable MWOS that could support multiple modes with low power consumption and high flexibility.Here,we propose and experimentally demonstrate a multifunctional MWOS based on asymmetric Y-junctions and multimode interference(MMI)couplers fabricated on a polymer waveguide platform.Both mode-insensitive and mode-selective switching functions can be achieved via selectively heating different electrode heaters.The fabricated device with the total length of∼0.8 cmshows an insertion loss of less than 12.1 dB,and an extinction ratio of larger than 8.4 dB with a power consumption of∼32 mW for both mode-insensitive and mode-selective switching functions,at 1550 nm wavelength.The proposed MWOS can also be scaled to accommodate more spatial modes flexibly and easily,which can serve as an important building block for MDM systems.

关键词： waveguide optical mode

Novel broad spectral response perovskite solar cells:A review of the current status and advanced strategies for breaking the theoretical limit efficiency

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Journal of Materials Science & Technology 2023年第9期140卷 33-57页

作者： Bin Liu Yuqi Wang Yanjie Wu Biao Dong Hongwei Song state key laboratory on integrated optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

Perovskite solar cells(PSCs)have revolutionized photovoltaic research.The power conversion efficiency(PCE)of PSCs has now reached 25.7%,which is comparable to current state-of-the-art silicon-based cells.However,PSCs can only utilize light of 300-850 nm,resulting in wasted near-infrared(NIR)light,which occupies 45%-50%of entire solar spectrum,which is one of the main reasons limiting the development of efficiency.Related strategies to broaden NIR spectroscopy to break the theoretical limit efficiency of PSCs have recently attracted extensive attention.This review firstly outlines theoretical basis for improving the NIR spectroscopy,then systematically summarizes some key strategies and research progress to improve NIR spectroscopy of PSCs.We firstly provided a comprehensive overview of historical research experiments on narrow-gap perovskite absorber layers,rare earth up-conversion,tandem devices,and integrated perovskite/organic solar cells and given constructive suggestions for exceeding limit efficiency of PSCs.Finally,based on the development status of PSCs with NIR utilization,the current issues,solutions and future development directions of important aspects to improve NIR utilization of PSCs are systematically discussed.This review lays the foundation for the efficiency of PSCs beyond the Shockley-Queisser limit,and provides a certain development prospect.

关键词： Organic materials Up-conversion materials Perovskite solar cells Tandem cells integrated perovskite/organic heterojunction solar cells

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奥斯瓦尔德熟化过程的控制

Science China Materials 2023年第3期66卷 1249-1255页

作者：董妍惠张丹李大光贾恒秦伟平 state key laboratory on integrated optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

作为一种热力学的必然过程,奥斯瓦尔德熟化通常会发生在材料生长的后期阶段,并导致材料的性能参数变差.几十年来,如何阻止或控制奥斯瓦尔德熟化一直是材料制备领域的一个挑战.尤其在纳米材料制备中,奥斯瓦尔德熟化已经成为了获得优良材... 详细信息

作为一种热力学的必然过程,奥斯瓦尔德熟化通常会发生在材料生长的后期阶段,并导致材料的性能参数变差.几十年来,如何阻止或控制奥斯瓦尔德熟化一直是材料制备领域的一个挑战.尤其在纳米材料制备中,奥斯瓦尔德熟化已经成为了获得优良材料的一大障碍.在大量实验和分析的基础上,本文发现临界浓度和时间窗口是阻止和抑制奥斯瓦尔德熟化发生的两个关键因素.我们利用全自动纳米材料合成仪,对制备NaREF4纳米材料的过程进行一系列精确控制,探明了奥斯瓦尔德熟化的规律,将熟化划分为三种类型.通过控制奥斯瓦尔德熟化的发生,不仅获得了高质量的纳米晶体,而且还开发了核-壳纳米材料制备策略.考虑到奥斯瓦尔德熟化的普遍性,这种方法可以应用于许多纳米材料的制备过程.

关键词：奥斯瓦尔德临界浓度纳米材料合成仪时间窗口后期阶段熟化材料制备

Flexible double narrowband near-infrared photodetector based on PMMA/core-shell upconversion nanoparticle composites

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Journal of Rare Earths 2022年第2期40卷 211-217,I0002页

作者： Ya’nan Ji Donglei Zhou Nan Wang Nan Ding Wen Xu Hongwei Song State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

Flexible narrowband near infrared(NIR)photodetectors(PDs)are urgently in demand in the fastdeveloping era of flexible electronics,due to their crucial roles in various innovative applications.Hence,we designed and synthesized the core-shell structured NaYF4:Yb^(3+),Er^(3+)@NaYF4:Nd^(3+)upconversion nanoparticles(UCNPs),which can be pumped by the 808 and 980 nm lights.The upconversion luminescence(UCL)are significantly enhanced after being assembled with the opal photonic crystals(OPCs)due to the photonic crystal effect,with 55 and 48 folds of enhancement factors under illuminations of 808 and 980 nm lights,respectively.Based on this hybrid,the flexible narrowband PDs were successfully fabricated on the PET substrate with the structure of OPCs/NaYF4:Yb^(3+),Er^(3+)@Nd^(3+)/MAPbl3,which displays excellent detection performance to double narrowband NIR light(808 and 980 nm)benefiting from the amplified UCL,with responsivity of 8.79 and 7.39 A/W,detectivity of 3.01×10^(11)and2.68×10^(11)cm·Hz^(1/2)/W for 808 and 980 nm lights detection respectively,along with short response time in the range of 120-160 ms.Furthermore,the OPCs/NaYF4:Yb^(3+),Er^(3+)@NaYF4:Nd^(3+)/MAPbI3 double narrowband PDs display low photodetection power threshold(0.05 W/cm2),outstanding flexibility,prominent moisture resistance,and good long-time stability.This work displays a new concept of narrowband NIR PDs,which open a new field for specific NIR light detections.

关键词： Upconversion luminescence Upconversion enhancement Narrow-band near-infrared photodetection Flexible photodetectors Rare earths

Ship Weather Routing Based on Hybrid Genetic Algorithm Under Complicated Sea Conditions

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Journal of Ocean University of China 2023年第1期22卷 28-42页

作者： ZHOU Peng ZHOU Zheng WANG Yan WANG Hongbo state key laboratory on integrated optoelectronics College of Electronic Science and EngineeringJilin UniversityJilin 130012China

Considering the effects of increased economic globalization and global warming,developing methods for reducing shipping costs and greenhouse gas emissions in ocean transportation has become crucial.Owing to its key role in modern navigation technology,ship weather routing is the research focus of several scholars in this field.This study presents a hybrid genetic algorithm for the design of an optimal ship route for safe transoceanic navigation under complicated sea conditions.On the basis of the basic genetic algorithm,simulated annealing algorithm is introduced to enhance its local search ability and avoid premature convergence,with the ship’s voyage time and fuel consumption as optimization goals.Then,a mathematical model of ship weather routing is developed based on the grid system.A measure of fitness calibration is proposed,which can change the selection pressure of the algorithm as the population evolves.In addition,a hybrid crossover operator is proposed to enhance the ability to find the optimal solution and accelerate the convergence speed of the algorithm.Finally,a multi-population technique is applied to improve the robustness of the algorithm using different evolutionary strategies.

关键词： genetic algorithm simulated annealing algorithm weather routing ship speed loss

Global modes and coupled modes for integrated twin circular-side octagon microlasers

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Science China(Information Sciences) 2022年第2期65卷 173-180页

作者： Ke YANG Yuede YANG Youzeng HAO Jiliang WU Yongtao HUANG Jiachen LIU Jinlong XIAO Yongzhen HUANG State Key Laboratory of Integrated Optoelectronics Institute of Semiconductors Chinese Academy of Sciences Center of Materials Science and optoelectronics Engineering University of Chinese Academy of Sciences

Whispering-gallery mode(WGM) microlasers are potential light sources for photonic integrated circuits and optical information processing. In this paper, an integrated twin circular-side octagon microlaser(TCOM) composed of two identical circular-side octagon microcavities(COMs) is proposed and demonstrated for realizing lasing mode control. In a TCOM, we found a global mode with the mode field of an "8" pattern(labeled "8" mode) in addition to weak coupling modes of traditional four-bounce modes. The "8" mode belongs to the whole coupled cavity and is insensitive to the refractive index offset of coupled COMs, but the weak coupling modes are strongly sensitive to the refractive index offset. Lasing mode transformation from multiple coupled modes to a single "8" mode is demonstrated by adjusting the refractive index offset through injection currents. Weak coupling modes for directly connected TCOMs and lasing mode control make the COM a potential unit for large-scale photonic integration and optical information processing.

关键词： optical microcavity semiconductor lasers coupled cavity lasing mode control photonic integration

Recent advances in Pb-Sn mixed perovskite solar cells

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Journal of Energy Chemistry 2022年第10期31卷 615-638,I0015页

作者： Yanyu Deng Guanhua Ren Danao Han Wenbin Han Zhuowei Li Chunyu Liu Wenbin Guo State Key Laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012JilinChina

Organic-inorganic hybrid lead-tin perovskite solar cells(Pb-Sn PSCs)have attracted much attention because of their advantages of low toxicity,variable bandgap,and feasibility for all-perovskite tandem solar cells,and the current power conversion efficiency(PCE)has exceeded 23%.However,due to the rambunctious crystallization process,easily oxidized Sn(Ⅱ)and inadequate energy level arrangement,there are many defects in perovskite films resulting in serious carrier recombination,which makes PCE still lag Pb-based PSCs.The quality of perovskite films is an important factor affecting the overall device performance.The selection and optimization of transport layers not only determines the interface energy level arrangement but also affects the carrier transport.In this paper,the research progress in improving performance of Pb-Sn PSCs in recent years is reviewed from aspects of perovskite layer and transport layers.The profound understanding of different promotion methods is summarized as well.These results have certain guiding significance for the future development and commercial application of Pb-Sn PSCs.

关键词： Pb-Sn mixed perovskite solar cells Crystallinity Charge transport layer Passivation Additive

Non-Halogenated Solvent-Processed High-Efficiency Polymer Solar Cells:the Role of Diphenyl Ether in Morphology,Light-Trapping,Transport Properties

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Transactions of Tianjin University 2022年第5期28卷 423-432页

作者： Yi Chen Xiangxu Ding Ge Wang Songwen Xiao Xin Liu Zihan Zhu Chen Wang Shanpeng Wen state key laboratory On integrated optoelectronics and College of Electronic Science and Engineering Jilin UniversityChangchun 130012China

There is an urgent need to use green non-halogenated solvents to prepare polymer solar cells(PSCs) for industrialization.It is time-consuming but necessary to find a suitable non-halogenated solvent/additive combination for a given donor:acceptor materials system.In this research,we report a non-halogenated binary solvent system toluene/diphenyl ether(DPE) for the PBDTT-DTffBT:PC_(71)BM and PM6:Y6 blending systems that exhibit comparable power conversion efficiency(PCE) to that of devices prepared with halogenated solvents.The nano scale morphology indicates that blending film processed solely with toluene has poor phase segregation and a rough surface,which hinders charge separation and interfacial contact.Besides,the total absorption spectra revealed significant light-trapping losses in the toluene-processed solar cells,resulting in low photocurrent generation.DPE incorporation addresses these issues and significantly improves the short-circuit current density and fill factor.Moreover,non-halogen solvent-processed devices exhibit high hole mobility and low transporting impedance properties.The present study enriches the families of eco-friendly,high-efficiency PSCs fabricated using nonhalogenated solvents.

关键词： Green solvents Diphenyl ether Morphology Charge extraction Polymer solar cells