| “Peak carbon dioxide emissions & Carbon neutrality” has become the main issue in China modernization development.Developing non-fossil fuel energy such as wind,solar,and tidal energy which is the key to constructing a clean,low-carbon,safe,and efficient energy system.The solar cell with the core of photovoltaic technology has grown rapidly,while the conversion efficiency of solar energy has been confined due to the available wavelength range and heat loss.The composites or devices based on the photothermoelectric effect may help to deal with the trouble of the solar cells encountered.The photothermoelectric effect,which is based on the photothermal conversion and thermoelectric effect,has the ultra-broadband response as not be limited by the band width.Moreover,the energy conversion efficiency can be further enhanced in aid of the heat produced by the non-radiation relaxation.Therefore,the research and development of high-performance photothermoelectric materials and devices have a great significance to promote solar energy utilization efficiency.The photo detections based on the photothermoelectric effect have been widely discussed and developed.The photothermoelectric response characters and the mechanisms of transportation of low-dimensional materials at specific wavelengths and temperatures have been revealed.Nonetheless,the research on photothermoelectric materials and the relevant devices based on such effects and applied on energy conversion is still insufficient.There is lacking of a clear and specific theoretical framework to guide the development of the photothermoelectric materials and their devices.The effects of the physical & chemical properties as well as the distribution states of functional fillers inside the composites on the photothermoelectric properties,carrier and phonon transportation behaviors remain to be further explored.The research of high-performance flexible photothermoelectric energy conversion devices is inadequate too.In order to address these issues,the research framework with the core of homogeneous synchronous & heterogeneous asynchronous conversion system was proposed,which is divided by the form and acquisition approach of thermal conversion.The organic/inorganic,inorganic non-self-supported photothermoelectric materials and their devices have been investigated in the inner the framework of homogeneous synchronous conversion system.Yet,targeted structure optimization and anti-electromagnetic interference functionalization researches of photothermal conversion layer were conducted inner the framework of heterogeneous asynchronous conversion system.The work of this thesis provides methods and ideas for the subsequent research on photothermoelectric materials and their devices with different architectures.The main conclusions of this thesis show below:(1)Here,the Polypyrrole(PPy)/Helical carbon nanotubes(HCNTs)homogeneous synchronous photothermoelectric composites which were prepared via in-situ polymerization on the surface of HCNTs to deal with the problems of low electrical transport behavior and low photothermal response of conductive polymer,as well as the issue of thermal transport behavior dramatic enhancement of substrates induced by the introduction of flawless carbon nanomaterials.First of all,the ultra-high photothermal response performance in the Near Infrared region(NIR),and the limited thermal transport behavior of HCNTs were researched and revealed.Next,the π-π interaction between the five-membered rings in the topological structures of HCNTs and PPy induces a locally ordered and dense packing of the polymer molecule chains,which promotes the transition of carriers type from polar to bipolar,and more interfaces with energy filtering effect were constructed.Such changes improve the conductivity and Seebeck coefficient of composites,yet suppressing the transportation of phonons,making it have both good thermoelectric properties and excellent photothermal response behavior.Then,the homogeneous synchronous photothermoelectric conversion module with single P architecture was designed and manufactured.The module has high output performance and high robustness,which can achieve over 720 μV and 62 n A output under the stimulation of 400 m W cm-2 NIR light,and the discrepancy between the periodic output signals is less than 4.2 %.Finally,such modules were integrated into an adjustable-delay optical switch that can be applied in Io T scenarios,which successfully realizes the delayed turn-on and turn-off control of light-emitting diodes with different forward voltages.(2)The Poly(3,4-ethylenedioxythiophene)polystyrene sulfonate(PEDOT:PSS)/HCNTs films prepared by introducing HCNTs into PEDOT:PSS solution were applied to try to solve the problem of the low light absorption properties of solution-processable conductive polymers represented by PEDOT:PSS,and to further verify the interaction mechanism between HCNTs and five-membered heterocycle-containing conducting polymers proposed by this thesis.First,the invisible patterned substrate technology was proposed to address the issue of arbitrarily shape droplet formation on the surface of specific flexible substrate.Second,the π-π stacking domain size of PEDOT molecular chains are greatly promoted after the introduction of HCNTs,and the conformation of the molecular chain changes to a more extent quinoid structure.The aforementioned changes lowered down the tunneling distance and the migration barrier,the carrier mobility was finally improved.Then,it was found that the light absorption of matrix was exponentially improved by introducing a trace of HCNTs,as well as the photothermal response being enhanced simultaneously.Here,a pseudo-bilayer arc.was proposed to realize the electrical transport network optimization of thin films,and the construction of interface with energy filtering effect.The conductivity,Seebeck coefficient and mechanical properties of films are enhanced simultaneously,the thermal transport behavior is suppressed due to the multihierarchical micro-hole structure inner the films.the z T of the pseudo-bilayer arc.composite films can reach up to 0.01 at room temperature finally.In addition,the homogeneous synchronous photothermoelectric device with multi-P arc.was designed and prepared.The device can achieve 1116.01 μV and 483.29 μV stable output under the stimulation of NIR light with a power density of 166.01 m W cm-2 and natural sunlight,respectively.Furthermore,the device unfolds ultra-high flexibility and high robustness.The inner resistant variation and the output performance degeneration merely 1.42 % and6.00 % after 10000 times continuous bending,and the discrepancy between the periodic output signals is less than 5 %.Finally,the ideal output voltage of the electrical connection optimized device under 83.12 m W cm-2 NIR light irradiation can reach up to 1.50 m V simulated by the COMSOL software.(3)The patterned bi-steps β-Ag2 Se electrochemical synthesis technology was developed to deal with the problem of low output performance of organic photothermoelectric composites,as well as the problem of precisely Ag/Se atom ratio control by the traditionalβ-Ag2 Se electrochemical co-deposition methods.The β-Ag2 Se non-self-supported homogeneous synchronous photothermoelectric materials were prepared via the technology.Firstly,the columnar crystal growth mechanism of β-Ag2 Se is proposed,and the transformation of β-Ag2 Se columnar crystal to(00l)and(01l)oriented grain structure after heat treatment is revealed.The refined grains and numerous grain boundaries induced by the structure transition suppresses phonon propagation while maintaining excellent electrical transport behavior in the in-plane direction.Secondly,the Ag/Se atomic ratio ofβ-Ag2 Se films decreased with the prolongation of the electrochemical reaction time and finally tended to be stable.Accordingly,the carrier concentration and mobility of the β-Ag2 Se film change in trade-off.COMSOL finite element simulation confined that the substrate inhibited the thermal transport of the film.The PF and z T value of the β-Ag2 Se film can reach up to 2574 μWm!#K! " and 0.87 at room temperature,respectively.Finally,A homogeneous synchronous photothermoelectric conversion device based on PN architecture was developed where PEDOT:PSS serves as P type legs.Such a device has an ultra-broadband light response(from visible light to far-infrared region)and high robustness,which can achieve a stable output of 125.51 n W under the stimulation of NIR light at the power density of 166.01 m Wcm!".Furthermore,the performance loss of the device is less than 2 % and the discrepancy between the periodic output signals is less than3.13 % after 10000 times uninterrupted bending,which is the highest performance among the reported self-supported/non-self-supported β-Ag2 Se films/devices.(4)The thermal storage/release optimization and anti-electromagnetic interference functionalization of the photothermal layer are realized inner the framework of heterogeneous asynchronous photothermoelectric conversion system to address the issue of poor thermal government of photothermal layer and the thermoelectric modules electromagnetic interference(EMI)protection.Firstly,The PEDOT:PSS/MXene photothermal layer framework can induce polyethylene glycol(PEG)near the framework to form an ordered and dense planar Zigzag conformation while the remaining PEG molecular chains are preferentially packed in the(7/2)helical conformation along the(120)plane,which has greatly increased the phase transition enthalpy as well as phase transition temperature.Secondly,the MXene framework was reinforced by PEDOT:PSS,which endows the composite a better leakage resistance(≤0.66 %)and compressive resistance(1.88 k Pa,≤ 20 %).A high photothermal conversion efficiency(94.90 %)was achieved by adjusting the component of framework as well as constructing a multi-hierarchical reflective structure.The composite has multi-band(X and HF)EMI shielding performance,and the total shielding effectiveness can reach over 29.80 d B.The strong interaction between PEDOT:PSS and PEG enabled the partial removal of the insulating PSS,which changed the EMI mechanism from the absorption loss to the reflection loss.Finally,the optimized photothermoelectric conversion system has stable energy output performance(24 m V)and excellent delay output characteristics(5 m V,170 s)under real sunlight. |
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