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  本文選題：聚合物太陽能電池　切入點：第一性原理　出處：《鄭州大學》2017年碩士論文

【摘要】：高效本體異質結太陽能電池研究的重要方面之一是D-A共聚物給體材料的合理設計。本論文分別選取10種供體D單元和10種受體A單元,采用密度泛函理論,模擬了D、A單元及其相應共聚物的結構和帶隙變化。在此基礎上,研究了三種高短路電流給體材料P1(PDTG-PT)、P2(PNTz4T)、P3(DPPTT-T)的電子結構特性。通過分析其分子鏈構象、Bader電荷轉移等性質,表明他們是高短路電流有機太陽能電池D-A型給體材料的理想選擇。具體結果如下:(1)本文首先討論了稠合噻吩環(huán)個數(1至6個噻吩環(huán))對帶隙值的影響。結果顯示,并二噻吩的帶隙值最小,隨著噻吩環(huán)數目的增加,其帶隙值有增大趨勢。同時,這種趨勢隨著噻吩環(huán)個數的增多逐漸減弱。其次,苯環(huán)稠合噻吩環(huán)結構中苯環(huán)的個數對帶隙值也有較大影響。本文計算的D7、D9、D10的帶隙值依次為1.34eV、1.24eV、0.97eV。能夠看出,隨著苯環(huán)數目的增多,它們的帶隙值依次減小。(2)對噻吩并噻吩和苯并二噻吩同分異構體帶隙值的計算結果顯示:S原子分布在分子鏈兩側,鏈間空間位阻較小,相應結構的帶隙值較小;S原子分布在分子鏈同側,鏈間空間位阻較大,相應結構的帶隙值較大。本文計算的D3、D4結構帶隙值依次為0.89eV、1.94eV,D7、D8結構帶隙值依次為1.34eV、1.55eV。另外,橋原子替代對帶隙值產生較大影響。(3)含有噻唑單元和噻二唑單元的結構具有較強的得電子能力,原因是噻唑環(huán)和噻二唑環(huán)中都含有碳氮雙鍵,碳氮雙鍵上的未成對電子使得這兩類結構更容易得到電子。本文的計算結果顯示,在同等情況下,含有噻二唑環(huán)的結構比含有噻唑環(huán)的結構具有更強的得電子能力。另外,結構中含有內酰胺基團時也具有較強的得電子能力。(4)本文對P1、P2、P3三種材料的計算表明:基于P1、P2、P3光伏器件出現高短路電流的原因一方面是因為構成聚合物本身的供體單元或受體單元的帶隙值較小,另一方面是因為材料自身具有優(yōu)良的晶化性能與較好的立構規(guī)整性。另外,分子鏈構象的結果表明:P1的二級結構為螺旋型構象,P2和P3的二級結構為直鏈型構象;差分電荷密度的結果表明:螺旋型構象的P1結構D、A單元之間的電荷轉移較少,直鏈型構象的P2和P3結構的D、A單元之間電荷轉移量較多。(5)模擬DPPX-T系列聚合物的帶隙發(fā)現,其帶隙值隨著O、S、Se、Te原子半徑的增加逐漸減小。另外,差分電荷密度的結果表明,單噻吩π橋在D-A共聚物內充當更多受體單元的作用,與此相反,P3結構的并噻吩π橋充當更多供體單元的作用。本研究期望為設計高短路電流D-A型給體材料提供有價值的指導。
[Abstract]:One of the important aspects in the study of high efficiency bulk heterojunction solar cells is the reasonable design of D-A copolymers. In this paper, 10 donor D units and 10 receptor A units are selected, respectively, and density functional theory (DFT) is used. The structure and band gap changes of DU A unit and its corresponding copolymers were simulated. On the basis of this, the electronic structure characteristics of three kinds of high short circuit current donor materials, P1OPDTG-PTG, P2PNTz4TP3DPPTT-T), were studied. By analyzing their molecular chain conformation, Bader charge transfer, etc. The results are as follows: (1) in this paper, the effect of the number of thiophene rings on the band gap is discussed. The band gap value of dithiophene is the smallest, and the band gap value increases with the increase of thiophene ring number, and decreases with the increase of thiophene ring number. Secondly, the band gap value increases with the increase of thiophene ring number. The band gap value is also influenced by the number of benzene rings in the dense thiophene ring structure. The calculated band gap values of D7 / D9 / D10 are 1.34 EV / 1.24 EV / 0.97 EV respectively. It can be seen that the number of benzene rings increases with the increase of the number of benzene rings. The band gap values of thiophenothiophene and benzodithiophene isomers were calculated. The results show that the atom of S is distributed on the two sides of the molecular chain, and the steric hindrance between the chains is small. The band gap value of the corresponding structure is smaller than that of the corresponding structure. The band gap value of the corresponding structure is 0.89 EV ~ 1.94 eV ~ (7) V ~ (8) and 1.34 EV ~ (1.55) EV, respectively, and the band gap value of the corresponding structure is larger in the same side of the molecular chain, and the band gap value of the corresponding structure is larger than that of the corresponding structure, and the calculated band gap value of the D _ 3 / D _ 4 structure is 0.89 EV ~ 1.94 eV ~ (7) D _ (8). The structure of thiazole unit and thiadiazole unit has strong electron ability because both thiazole ring and thiadiazole ring contain carbon and nitrogen double bonds. The unpaired electrons on the carbon-nitrogen double bond make it easier for these two kinds of structures to get electrons. The results show that, under the same conditions, the structures containing thiadiazoles have a stronger ability to obtain electrons than those containing thiazoles. In this paper, the calculation of three kinds of P1P2P2P3materials shows that the reason for the high short-circuit current of P1P2P2P3 photovoltaic device is partly because of the donor of the polymer itself. The band gap of unit or receptor unit is smaller, The results of molecular chain conformation show that the secondary structure of 1 / P1 is a helical conformation, and that of P2 and P3 is a straight chain conformation. The results of differential charge density show that there is less charge transfer between P1 units with helical conformation, and the charge transfer amount between P2 unit of linear conformation and DKA unit of P3 structure is more. 5) the band gap of DPPX-T series polymers is simulated. The band gap value decreases gradually with the increase of the atomic radius of OFS-Se Te. In addition, the differential charge density shows that the thiophene 蟺 bridge acts as more receptor units in D-A copolymers, and the difference charge density shows that the thiophene 蟺 bridge acts as more receptor units in the D-A copolymers. On the contrary, the thiophene 蟺 bridge with P3 structure acts as more donor units. This study is expected to provide valuable guidance for the design of D-A type donor materials with high short-circuit current.
【學位授予單位】：鄭州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM914.4

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