本文關(guān)鍵詞：聚合物太陽能電池中載流子復(fù)合與傳輸機(jī)制及器件特性的研究　出處：《北京交通大學(xué)》2014年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 聚合物太陽能電池 電荷轉(zhuǎn)移態(tài)復(fù)合 界面修飾 載流子傳輸與復(fù)合 電容-電壓特性

【摘要】：摘要：聚合物太陽能電池中的物理過程對器件效率的提升具有重要的指導(dǎo)意義,在聚合物：富勒烯器件中,載流子復(fù)合、傳輸及收集的分析對其光伏特性的改善是十分重要的；復(fù)合過程中給體受體界面處的電荷轉(zhuǎn)移態(tài)(Charge Transfer State,CTS)復(fù)合與器件的開路電壓(Voc)及短路電流(Jsc)直接相關(guān)；活性層與電極之間的界面修飾可以改善載流子的傳輸與收集,從而提高器件特性。 本論文中,首先通過外量子效率光譜響應(yīng)(EQE)及電致發(fā)光(EL)探測了聚合物太陽能電池的電荷轉(zhuǎn)移態(tài)吸收與復(fù)合發(fā)光,發(fā)現(xiàn)除了給體材料和受體材料的EQE及EL特征外,出現(xiàn)了更低能量的CTS特征響應(yīng),且此CTS特征響應(yīng)與給體材料和受體材料各自的最高占有軌道(HOMO)及最低未占有軌道(LUMO)能級差的變化趨勢通常是相一致的。另外,利用精細(xì)平衡理論,研究了電荷轉(zhuǎn)移態(tài)響應(yīng)中EQE與EL的聯(lián)系,通過EL光譜理論計(jì)算而得的EQE曲線與實(shí)際測量的曲線相吻合。隨后通過電荷轉(zhuǎn)移態(tài)EQE及EL計(jì)算了器件的理論開路電壓值,計(jì)算的開路電壓結(jié)果與實(shí)際測量的有一定差距,在0.3～0.45V之間,但是已經(jīng)與實(shí)際結(jié)果接近。通過電致發(fā)光外量子效率(QLED)及特征能量(Ech)對開路電壓的計(jì)算進(jìn)行了修正,使得計(jì)算結(jié)果與實(shí)驗(yàn)值最大偏差縮小到0.15V左右。研究了不同外加電壓(注入電流)下,器件CTS復(fù)合EL峰值位置的變化,發(fā)現(xiàn)實(shí)際測量到的EL峰值位置隨注入電流的變化比理論分析值要小。其可能的原因?yàn)?靠近準(zhǔn)費(fèi)米能級處低能態(tài)的載流子不容易移動,需要通過去陷(detrapping)過程,抬高其中的一個電子或者空穴到更高的載流子可以自由移動的能級,移動之后與另外相應(yīng)的載流子復(fù)合而發(fā)光。 借助于電容-電壓測試,研究了緩沖層對聚合物太陽能電池中載流子傳輸與復(fù)合的影響。介紹了聚合物太陽能電池中的電容-電壓(C-V)特性,并從載流子傳輸及界面勢壘兩方面分析了其對C-V曲線的影響。研究了Mo03及NPB修飾層對器件特性的影響,適當(dāng)厚度的修飾層可以改善器件的載流子傳輸和減小界面注入勢壘,從而提高器件的短路電流及開路電壓。過厚的修飾層增加器件串聯(lián)電阻,阻擋載流子的注入與收集,引起載流子在器件內(nèi)的大量復(fù)合。借助C-V測試研究了修飾層對載流子復(fù)合及收集的影響,適當(dāng)厚度的修飾層改善載流子收集。初步研究了器件Voc與VCmax之間的關(guān)系,通過理論分析及實(shí)驗(yàn)我們發(fā)現(xiàn),器件的Voc表示器件中的載流子復(fù)合與產(chǎn)生相等,VCmax表示載流子的復(fù)合超過電子在給體材料LUMO狀態(tài)密度函數(shù)的積累,兩者大小接近但存在差異。 研究了聚合物太陽能電池中的界面復(fù)合及對器件特性的影響。首先,對比了雙層結(jié)構(gòu)與體異質(zhì)結(jié)結(jié)構(gòu)器件的J-V及QLED隨注入電流的變化。由于雙層結(jié)構(gòu)不利于激子的解離,所以短路電流較體異質(zhì)結(jié)的都小。研究了載流子遷移率對QLED的影響,實(shí)驗(yàn)發(fā)現(xiàn)材料的載流子遷移率越高,越可能發(fā)生電子與空穴在金屬電極處的猝滅。初步研究了器件Jsc與QLED的關(guān)系,電荷轉(zhuǎn)移態(tài)電致發(fā)光的QLED代表了電子空穴的復(fù)合程度,復(fù)合程度越小,被外電路所收集的載流子越多,EQE的值就會大,器件的短路電流越高(在不考慮材料的光響應(yīng)范圍的話)。值得注意的是,對于開路電壓而言,需要器件中的輻射發(fā)光占全部復(fù)合過程比例越多越好,即希望大的QLED,但是對于器件的短路電流而言,需要器件中的載流子復(fù)合盡可能小,即小的QLED,所以對于器件的QLED,存在最佳值。
[Abstract]:Abstract: it is an important guiding significance to enhance physical processes in polymer solar cells on the efficiency of the device in the polymer: fullerene device, carrier recombination, analysis of the transmission and collection of improvement on the photovoltaic properties is very important; composite process to body body at the interface of the charge transfer state (the Charge Transfer State. CTS) and open circuit voltage composite device (Voc) and short circuit current (Jsc) directly related; interface modification between the active layer and the electrode can improve the transmission and collection of carriers, so as to improve the device characteristics.
In this paper, firstly, the external quantum efficiency of the spectral response (EQE) and electroluminescence (EL) charge detection of the polymer solar cell transfer state absorption and luminescence, found that in addition to the EQE and EL features of the body material and the receptor material, the lower energy CTS characteristic of the response, and the characteristics of CTS in response to the body material and the receptor material and their highest occupied molecular orbital (HOMO) and LUMO (LUMO) changes the energy level difference is usually consistent. In addition, by using the precise balance theory, the study of EQE and EL in response to the charge transfer state, EQE curve by EL spectroscopy and theoretical calculation consistent with the actual measurement curve. Then through the charge transfer state of EQE and EL open circuit voltage device theory calculation, there is a certain gap between the open circuit voltage calculation results and actual measurement, between 0.3 ~ 0.45V, but with the actual Results close. The external quantum efficiency by electro luminescence (QLED) and the characteristics of energy (Ech) to calculate the open circuit voltage is modified, the calculation result and the experimental value is reduced to about 0.15V. The maximum deviation of different applied voltage (current), change device CTS composite EL peak position, peak changes the location of the EL measured with the injected current value is much smaller than theoretical analysis. The possible reason for the carrier, near the Fermi level at low energy state is not easy to move, need to go through the depression (detrapping) process, raise one of the electrons or holes to higher carrier level can move freely. After moving with the addition of the corresponding carrier composite light.
With the help of capacitance voltage test of buffer layer on the carrier transport and recombination in polymer solar cells. The effects of introduced capacitance in polymer solar cell voltage (C-V) characteristics, and analyzes its influence on the C-V curve from the two aspects of carrier transport and interface barrier. The effects of Mo03 and effect of NPB modified layer the device characteristics, the proper thickness of the modified layer can improve the device carrier transmission and reduce the interface injection barrier, so as to improve the short-circuit current and open circuit voltage of the device. The thickness of the modified layer increases the series resistance of the device, blocking the carrier injection and collection, caused by the carrier in the inside of the device. A lot of composite effect of modification the layer recombination and collected by C-V test, modified layer thickness to improve the carrier collection. The relationship between Voc and VCmax devices were studied, through theoretical analysis and We find that the Voc of the device indicates that the carrier recombination is equivalent to that in the device. VCmax indicates that the recombination of carriers exceeds the accumulation of electron state density function of LUMO in the donor material, and the size of them is close but different.
Study on polymer solar cells in the composite interface and the device characteristics. First, comparing J-V and QLED devices with double layer structure of bulk heterojunction with the variation of current injection. Because the structure is not conducive to the double dissociation of exciton, so a short-circuit current of bulk heterojunction are small. The influence of the carrier mobility for QLED, materials found the carrier mobility is high, the more likely the quenching of electrons and holes in the metal electrode. The study on the relation between Jsc devices and QLED, the compound degree of charge transfer state of El QLED on behalf of the electron hole, the compound degree of smaller, more carriers are collected the external circuit, the EQE value will be higher, short-circuit current of the device (without considering the material light response range of words). It is worth noting that the open circuit voltage, the light emitting device to total radiation The more complex part is, the better it is, that is to say that the larger QLED is expected. However, for the short circuit current of the device, the carrier complex in the device is as small as possible, that is, a small QLED, so there is an optimum value for the QLED of the device.

【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TM914.4

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相關(guān)期刊論文 前1條

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本文編號：1392463