Abstract

The non-doped and alkali (Na,K)-doped Cu₂ZnSnS₄ (CZTS) thin films were prepared using the sol–gel spin-coating method on the glass substrate, and the changes in the structural, optical, and electrical characteristics of the films were examined and compared. The structural study results obtained showed that all the prepared samples had a kesterite structure. The scanning electron microscopy and Raman analysis showed that the samples' surface and crystalline quality were significantly changed by doping, and an appropriate amount of dopants can improve them. The optical study showed that the energy gap values for the CZTS layers were in the range of 1.40–1.61 eV, which is desirable for solar cells. Moreover, good optical conductivity values (10¹²–10¹⁵ s^–1) and high absorption coefficients (up to 1.8 × 10⁵ cm^–1 in the visible region) were obtained for the CZTS thin films. Investigation of the sample’s electrical properties indicated that non-doped and doped CZTS was p-type, and therefore doping did not change the type of the charter of thin films. Moreover, the carrier concentration of the samples significantly increased up to 8.00 × 10¹⁹ cm^–3 (one order of magnitude increase) with the doping. The samples’ photovoltaic properties showed that the fabricated ZnS|CZTS hetero-junction exhibited good rectifying behavior and the doped layers had better diode parameters. Overall, the results showed that the CZTS thin films doped with an appropriate amount of dopants (1% Na and 1.5% K) had better structural, optical, and electrical properties. The photo-electrical study of the samples showed that for all samples, photocurrent under illumination significantly increased (especially for Na-doped CZTS thin films), indicating that the CZTS thin films are suitable for solar energy conversion.

中文翻译：

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溶胶-凝胶法制备碱（Na，K）掺杂Cu 2 ZnSnS 4薄膜的研究

摘要

利用溶胶-凝胶旋涂法在玻璃基板上制备了非掺杂和碱（Na，K）掺杂的Cu ₂ ZnSnS ₄（CZTS）薄膜，并改变了结构，光学和电学特性的电影检查和比较。所获得的结构研究结果表明，所有制备的样品均具有钾钛矿结构。扫描电子显微镜和拉曼分析表明，掺杂后样品的表面和晶体质量发生了显着变化，适量的掺杂剂可以改善其质量。光学研究表明，CZTS层的能隙值在1.40–1.61 eV的范围内，这对于太阳能电池而言是理想的。此外，良好的光导率值（10 ¹² –10CZTS薄膜获得¹⁵ s ^–1）和高吸收系数（在可见光区域高达1.8×10 ⁵ cm ^–1）。对样品的电性能的研究表明，未掺杂和掺杂的CZTS为p型，因此掺杂不会改变薄膜的宪章类型。此外，样品的载流子浓度显着提高到8.00×10 ¹⁹ cm ^–3（增加一个数量级）与掺杂。样品的光伏性能表明，所制备的ZnS | CZTS异质结具有良好的整流性能，掺杂层具有更好的二极管参数。总体而言，结果表明，掺有适量掺杂剂（1％Na和1.5％K）的CZTS薄膜具有更好的结构，光学和电学性能。样品的光电研究表明，对于所有样品，光照下的光电流都显着增加（尤其是掺钠的CZTS薄膜），这表明CZTS薄膜适用于太阳能转换。