鈣鈦礦氧化物薄膜及其層狀複合結構之光電流表現

The Photocurrent Behavior of Perovskite Oxide Thin Films and Their Layered Structures

方家宇(Chia-Yu Fang)

指導教授 ： 謝宗霖

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.00053

摘要

本研究討論異相反應光觸媒(heterogeneous photocatalyst)在光電極的應用，材料的選擇為鈣鈦礦氧化物SrTiO3、AgNbO3及其固溶體(SrTiO3)x(AgNbO3)1-x薄膜，著重於觀察這三者間heterojunction的效應。實驗結果顯示，SrTiO3與AgNbO3所形成之層狀複合結構(SrTiO3/AgNbO3)，其光電流表現較SrTiO3與AgNbO3薄膜皆來得優異，是由於層狀複合結構之間存在內建電場，能夠降低激發電子與電洞recombination的機率，讓實際參與光解水反應的載子數量有效增加；另外，利用結構與性質介於SrTiO3與AgNbO3之間的(SrTiO3)0.5(AgNbO3)0.5固溶體薄膜作為匹配層，以匹配SrTiO3與AgNbO3形成界面品質更佳之層狀複合結構，其光電流表現又較SrTiO3/AgNbO3提升了一倍以上。
光電極的製備上，以溶膠-凝膠法製備SrTiO3、AgNbO3及其固溶體(SrTiO3)x(AgNbO3)1-x薄膜，所選用的基材為具備導電性與高透光度的ITO玻璃，及高化學穩定性且導電性極優的白金電極。ITO玻璃高透光度的特性能夠增加光電極在應用面與實驗設計面的廣度，此為本研究首選之基材。由於ITO玻璃不耐高溫，本研究成功利用PLT晶種層及高分子PVP360之添加，讓SrTiO3、AgNbO3及SrTiO3/AgNbO3薄膜得以於低溫下製備在ITO玻璃之上。利用溶膠-凝膠法製備(SrTiO3)x(AgNbO3)1-x薄膜為本研究首創，目的是為了調查其與SrTiO3/AgNbO3之間的匹配關係對於光電流性質的影響。以(SrTiO3)0.5(AgNbO3)0.5薄膜作為SrTiO3/AgNbO3匹配層之層狀複合結構，需在高溫下才能夠成相，故以可耐高溫之白金電極作為基材。

關鍵字

光電流 ； 光電極 ； heterojunction ； 層狀複合結構 ； SrTiO3 ； AgNbO3 ； (SrTiO3)x(AgNbO3)1-x

並列摘要

In this study, we discuss the application of heterogeneous photocatalyst in photoelectrochemical cell. Two kinds of perovskite oxide thin films, SrTiO3 and AgNbO3, and their solid solution, (SrTiO3)x(AgNbO3)1-x were chosen as sample photoelectrode materials to study the effect of “heterojunction” on their photocurrent responses. It is found that the photocurrent responses of SrTiO3/AgNbO3 layered structures were higher than both the SrTiO3 and AgNbO3 thin films due to the help of “build-in electrical field” which could accelerate the separation of photoinduced e--h+ pairs and reduce the recombination effect. Furthermore, (SrTiO3)0.5(AgNbO3)0.5 thin film was used as a intermediate matching layer to improve the interface quality of SrTiO3/AgNbO3 layered structure. The photocurrent response was further improved by such approach.
Sol-gel process was used to fabricate SrTiO3, AgNbO3 and (SrTiO3)x(AgNbO3)1-x thin films on ITO-coated glass or platinum-coated silicon wafer substrates. ITO-coated glass was chosen because of its high transparency, which can offer a wide range of applications. The shortcoming of ITO-coated glass is that it cannot endure temperature processing above 500 °C. In the study, (Pb0.86La0.14)TiO3 seeding layer and PVP modified sol-gel process were used to fabricate SrTiO3 and AgNbO3 thins films and their layered structures on ITO-coated glass substrates at 500 °C. Furthermore, the method of preparing (SrTiO3)x(AgNbO3)1-x thin films by sol-gel process is reported for the first time.

並列關鍵字

Photocurrent ； Photoelectrode ； Heterojunction ； Layered structures ； SrTiO3 ； AgNbO3 ； (SrTiO3)x(AgNbO3)1-x

參考文獻

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