以電鍍法製備銅銦硒太陽能吸收層及熱處理製程之探討

The Heat Treatment Research of CuInSe2 Solar Cell Absorber Layer by Electrodeposition Process

柳俊銘(Jun-Ming Liu)

指導教授 ： 林招松

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.02401

摘要

CuInxGa(1-x)Se2/CuInSe2是目前為薄膜太陽能電池中較為有競爭力的一種太陽能電池材料，其擁有高的光電轉換效率、良好的吸收係數和較寬的吸收光譜。本論文將以電化學沉積法製備CuInSe2吸收層並探討熱處理製程的影響。
實驗分成兩個部分，第一部分是電化學沉積的探討，將利用定電位單槽電鍍同時電鍍三元元素，直接生成合乎劑量比的CuInSe2吸收層，因電鍍電位在-0.6 < E < -0.7 V(vs. SCE)範圍，此時Mo基板的催氫還原效應會導致表面形貌的不均。因此，實驗將以三種Mo基板的前處理鈍化Mo基板表面，分別為酸浸、空氣中加熱、濺鍍通氧鈍化。實驗結果為酸浸和空氣中加熱鈍化方法比較好控制，而且在後續電鍍製程能夠得到較為平整的CuInSe2吸收層，濺鍍通氧鈍化由於電阻過高，導致後續電鍍製程CuInSe2吸收層較薄。
第二部分則是探討初鍍CuInSe2吸收層的熱處理製程，由於前面實驗已經可以得到平整，且合乎劑量比的吸收層，因此嘗試避開硒化製程，而在初鍍CuInSe2吸收層表面，以溶膠凝膠法和浸泡塗佈法製備一層SiO2，透過保護的方式進行熱處理，另一方面則是以硒化製程進行熱處理，探討硒顆粒的重量、溫度對於熱處理的影響。前部分的實驗可以在500℃、20分鐘的熱處理時間，得到良好的CuInSe2吸收層，但是因電鍍製程本身所含的空缺較多，而導致電性變成簡併半導體而失敗。而後在硒化製程中，可以在足夠硒元素、550℃、40分鐘得到顆粒大小約為2 μm的良好CuInSe2吸收層，並以光電化學法評估其電性為p-type半導體。在比較不同平整度的初鍍CuInSe2吸收層對硒化製程後的影響，可以得知需要有足夠平整的CuInSe2吸收層，對於後續熱處理是極為重要的。

關鍵字

銅銦硒/銅銦鎵硒 ； 硒化處理 ； 太陽能電池 ； 薄膜 ； 電化學 ； 電鍍

並列摘要

CuInxGa(1-x)Se2/CuInSe2 based solar cells have been reported with better competitiveness in the generation of thin film solar cells duo to its high photoelectron transfer efficiency, good absorption coefficient and board absorption spectrum. This study thus focuses on the heat treatment of CuInSe2 absorber layer manufactured byelectrodeposition.
The experiment is divided into two parts. The first part is the manufacture of CuInSe2 layer with electrodeposition process. The stoichiometric CuInSe2 absorb layer is electroplated in a single solution system at a constant potential. Since the CuInSe2 reduction potential is closed to the H2 discharge. Creating a passivated Mo surface for retarding H2 bubble formation and getting a smooth, compact CuInSe2 structure are important Therefore, there are three approaches in this study, to passivate the molybdenum matrix for avoiding H2 reduction and current concentration effect by acid immersion, oxidization in heated air and aerating oxygen in the end of Mo matrix sputtering. The surface morphology of CuInSe2 absorb layer can be easily smoothed and controlled by the acid immersion and oxidization in heated air pre-treatment of the Mo matrix. However, due to high rate of oxidation of aerating oxygen in sputtering, the resistance of the matrix is much higher than the other two methods which results in insufficient thickness CuInSe2 layer in the following electroplating process.
Second part is the research of the heat treatment of electrodeosited CuInSe2 layer. In the first part experiment, a smooth and stoichiometric CuInSe2 can be well-control. A new heat treatment is attempted, that is, a SiO2 coating formed by Sol-gel dipping process protects the CuInSe2 during heat treatment without selenium atmosphere. On the other hand, the selenization treatment is also a important direction in this study, considering the influence of amount of selenium, temperature and time on selenizaiton. In the front part of research, it can have a almost good cross-sectional morphology after 20 min heat treatment at 500℃ but it also has electric property problem due to vacancy defects during electroplating. In selenizaition research, it can have a pretty good morphology with enough amount of selenium after 40 min heat treatment at 550℃. Moreover, a p-type and 2μm-thickness absorb layer with the photoelectrochemical cell testing is fabricated in the selenizaition heat treatment. At the end, contrasting the different smoothness electrodeposited CuInSe2 layer during the heat treatment, it was found that the smoothness during electrodepostion is important for manufacturing good CuInSe2 absorber layer during heat treatment.

並列關鍵字

CIS ； CIGS ； Selenization ； Solar cell ； Thin film ； Electrochemical ； Electroplating

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