多種類型鈣鈦礦太陽能電池與製作之研究

Abstract

在環境污染、資源短缺日益加劇的的情況下，太陽能作為一種可再生能源的發展刻不容緩。為瞭解決能源的可替代問題，科學家們研究出了許許多多種類型的太陽能電池，而傳統矽太陽能電池由於其不俗的光電轉換效率和穩定性長期以來被當做是太陽能電池的主要規模化生產的材料，但是生產成本過於高昂以至於各國在推進商業化的過程不斷碰壁，就在太陽能產業發展困難的時候，鈣鈦礦一詞出現在了人們的眼前，憑藉著優異的光電特性和較低的材料成本，再加上製作過程也相對簡單，鈣鈦礦成為當下最有潛力的太陽能電池材料，而短短數年間，鈣鈦礦太陽能電池的光電轉換效率也從不到10%迅速上升到25.2%，逐漸接近了矽太陽能電池的當下最高的光電轉換效率的世界紀錄。 雖然採用一步驟溶液法可以很容易製作出鈣鈦礦太陽能電池，但是過於依賴個人手法，容錯率較低，難以大量生產。而作為半導體材料領域的常用製作手段，採在真空環境下加熱蒸發固體粉末的鍍膜方法被看做是鈣鈦礦太陽能電池工業化中最具潛力的方法，但是製作成本高，且難以完全反應便是限制其發展的障礙。本研究階段為此提出了一種新的方法可以有效解決上述問題。結合溶液法和蒸鍍製程，本研究採用實驗室新創的製作方法三明治蒸鍍法，並創新提出(Growth process control) GPC生長控制技術以及(Solvent annealing) SA溶劑輔助加熱技術。將MAI作為種子層旋塗在塗有PEDOT:PSS的ITO基板上，並分別用蒸鍍完成PbI2和MAI粉末，其中，MAI粉末通過實驗室自製的低真空SET腔體製作並退火形成MAPbI3鈣鈦礦主動層，基於MAI-PbI2-MAI的雙互擴散的原理，MAI和PbI2會擴散到中間層PbI2之中並且形成MAPbI3鈣鈦礦，將製作好的元件至於低真空下生長一段時間後，隨著時間的增長，鈣鈦礦層逐漸完全反應，蒸鍍製程中存在的過量未反應的PbI2殘留物也被完全消除。最終形成高結晶度的MAPbI3鈣鈦礦太陽能電池。所製作的太陽能電池最高效率可以達到16.4%。 在傳統的MAPbI3鈣鈦礦中加入一定比例的Br和Cl有助於光譜範圍藍移以及開路電壓上昇，因此摻雜氯的鈣鈦礦一直被認為是鈣鈦礦太陽能電池和矽太陽能電池結合的最好選擇。而通常要實現摻雜工藝往往會採用溶液法去完成，若能採用蒸鍍製程製備，對於大量生產來說具有非常重要的意義。而本研究階段開發溶劑輔助蒸發技術，利用三明治蒸鍍法製備MAPbIxCl3-x的鈣鈦礦之後，在利用一定比例的DMSO前驅液的進行溶劑輔助加熱處理，不但可以讓蒸鍍法所製作的MAPbIxCl3-x具有非常完整的成膜度，還能大幅提升所製作出的太陽能電池的光電性能。最終我們所製作出的含氯鈣鈦礦太陽能電池最高效率達到15%。 雖然作為當下太陽能電池的明星材料，傳統鈣鈦礦材料MAPbI3還是存在諸如穩定性差，光照下易分解，光譜範圍有限等問題。為了有效解決這些問題，本研究提出了兩種有效的光譜調變手段。首先，採用溶液法，研製出全無機鉛錫共摻雜鈣鈦礦太陽能電池和2D+3D新型Cs base鉛錫共摻雜鈣鈦礦太陽能電池。摻雜一定比例Sn可以讓鈣鈦礦光譜紅移，加入一定濃度的二維材料PEAI可以提高無機鈣鈦礦的相位穩定性，眾所周知，A位有以機大分子離子為主的鈣鈦礦諸如MAPbI3在光照下容易產生分解，而以無機Cs為主的鈣鈦礦結構在光照下較為穩定。我們製作出效率達到16.1%的無機為主體的鈣鈦礦太陽能電池。

With the increasing environmental pollution and resource shortage, the development of solar energy as a renewable energy is important. To solve the problem of substitution of energy source, scientists have developed many types of solar cells. Because of its excellent photoelectric conversion efficiency and stability, traditional silicon solar cells have been regarded as the main materials for large-scale production of solar cells, but the cost of production is too high. When the development of solar energy industry is difficult, perovskite with excellent photoelectric properties and low material cost, plus the relatively easy manufacturing, has become the most potential solar cell material. In a short few years, the photoelectric conversion efficiency of perovskite solar cells has risen rapidly from less than 10% to 25.2%, it has gradually entered the world record of the highest photoelectric conversion efficiency of silicon solar cells. Although perovskite solar cells can be easily produced by one-step solution method, it is difficult to mass produce due to its low error tolerance and over dependence on personal techniques. As a common manufacturing method in the field of semiconductor materials, the evaporation method in vacuum environment is regarded as the most potential method in the industrialization of perovskite solar cells, but the high manufacturing cost and the difficulty of complete reaction are big obstacles to its development. A new method is proposed to solve the above problems. Combined with the solution method and the evaporation process, the sandwich evaporation method, which is a new manufacturing method developed in our laboratory, is adopted in this study. The (growth process control) GPC growth control technology and (solvent annealing) SA solvent assisted heating technology are innovated. MAI, used as the seed layer, was spin-coated on ITO substrate coated with PEDOT: PSS. PbI2 and MAI powders were evaporated respectively. Among them, MAI powder was made by low vacuum SET cavity, made in our laboratory, to form MAPbI3 perovskite active layer. Based on the principle of dual diffusion of MAI- PbI2-MAI, MAI would diffuse into PbI2 intermediate layer and form MAPbI3 perovskite, which would make good performance after a period of time of growth in low vacuum. With the increase of time, the perovskite active layer gradually reacts completely, and the excessive unreacted PbI2 residue in the evaporation process is eliminated completely. Finally, a high crystallinity MAPbI3 perovskite solar cell was formed. The highest efficiency of the solar cell could reach 16.4%. Adding a certain proportion of Br and Cl to the traditional MAPbI3 perovskite helps shift the spectral range toward blue spectrum and increase the open circuit voltage. Therefore,the chlorine Doped Perovskite has been considered as the best choice for the combination of perovskite solar cells and silicon solar cells. The solution process is usually used to realize the doping process. If we can use the Deposition process, it is very helpful for mass production. In this research stage, the solvent annealing Deposition technology is developed. After the perovskite of MAPbIxCl3-x prepared by sandwich evaporation method, a certain proportion of DMSO precursor solution is used for solvent annealing treatment, which can not only make the MAPbIxCl3-x produced by evaporation method have a very complete film, but also greatly improve the photoelectric performance of the solar cell. Finally, the efficiency of the perovskite solar cell is 15%. As the star material of solar cell, MAPbI3, a traditional perovskite material, also has some problems such as poor stability, easy decomposition under light, limited spectral range and so on. To solve these problems, two effective methods of spectral modulation are proposed. First, a new type of Cs base lead-tin mixed perovskite solar cell was developed by solution process. Doping a certain proportion of Sn can make the spectrum of perovskite red shift, adding a certain concentration of two-dimensional material PEAI can improve the phase stability of inorganic perovskite. As we all know, perovskite with organic macromolecular ions as the main position, such as MAPbI3, is easy to decompose under light, while perovskite structure with organic Cs as the main position is relatively stable under light. We have made perovskite solar cells with an efficiency of 16.1%.