UV to NIR photon conversion in Nd-doped rutile and anatase titanium dioxide films for silicon solar cell application

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• 作者：E. Le Boulbar^a ; ^{emmanuel.leboulbar@gmail.com} ; ^{E.Le.Boulbar@bath.ac.uk} ; E. Millon^a ; E. Ntsoenzok^b ; B. Hakim^b ; W. Seiler^c ; C. Boulmer-Leborgne^a ; J. Perri&egrave ; re^d
• 关键词：Titanium dioxide ; Anatase ; Rutile ; Neodymium ; Photoluminescence ; Down shifting
• 刊名：Optical Materials
• 出版年：2012
• 期刊代码：81_09253467
• 类别：ch
• 出版时间：June, 2012
• 卷：34
• 期：8
• 页码：1419-1425
• 文件大小：1033 K

摘要

Undoped and Nd-doped titanium dioxide anatase and rutile films have been grown by pulsed-laser deposition at 700 掳C under 0.1 mbar O₂. By selecting adequate substrates, TiO₂ films doped with 1, 2 or 5 at.%Nd were grown and constituted with polycrystalline rutile, highly oriented (2 0 0) rutile film, or oriented (0 0 4) anatase. An UV to NIR photon conversion is evidenced in the films. Indeed, intense and well-resolved emission lines from Nd³⁺ have been observed upon excitation above the TiO₂ bandgap at room temperature. The sensitised emission of Nd³⁺ is found to be much efficient in rutile than in anatase structure. Low temperature photoluminescence measurements lead to fine resolved peaks corresponding to the Nd³⁺ 4f transitions with different spectral characteristic according to the host matrix used. Photoluminescence dependence temperature evidences that the light emission from Nd³⁺ in anatase-based films is probably influenced by the presence of self-trapped excitons or by orbital interaction. Mechanisms of sensitisation host to Nd³⁺ are proposed for both matrixes. Finally, the Nd dopant concentration and the microstructure of TiO₂ rutile films are found to affect the photoluminescence emission intensity. Rutile film (2 0 0) oriented is the most adapted host matrix to sensitise 1 at.%Nd³⁺ ions for an emission around 1064 nm making such Nd-doped layers interesting for photon conversion by down shifting process.