Aluminum Doped Zinc Oxide (AZO) produced by radio frequency (RF) magnetron sputtering is thought to be the prospective replacement of the de facto standard indium tin oxide (ITO) anode in organic solar cells. In order to achieve a proper resistivity and transmittance of AZO thin film compared to ITO, a systematic study was done to optimize the sputtering conditions. In this work, two primary parameters: target-substrate distance and sputtering power, were optimized, and a optimized film thickness was determined. A poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) bulk-heterojunction organic solar cell was fabricated based on the optimized parameters and the power conversion efficiency reached 0.83%. A theoretical analysis is given to explain the optimization process. This work provides a clear pathway to substitute AZO for ITO in organic solar cells for future mass production.

Aluminum Doped Zinc Oxide (AZO) produced by radio frequency (RF) magnetron sputtering is thought to be the prospective replacement of the de facto standard indium tin oxide (ITO) anode in organic solar cells. In order to achieve a proper resistivity and transmittance of AZO thin film compared to ITO, a systematic study was done to optimize the sputtering conditions. In this work, two primary parameters: target-substrate distance and sputtering power, were optimized, and a optimized film thickness was determined. A poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) bulk-heterojunction organic solar cell was fabricated based on the optimized parameters and the power conversion efficiency reached 0.83%. A theoretical analysis is given to explain the optimization process. This work provides a clear pathway to substitute AZO for ITO in organic solar cells for future mass production.

Aluminum doped zinc oxide AZO has been studied for 20 years. It can improve thin films¡¦ thermal stability and transparency in visible range .However AZO is not as good as ITO in conductivity and transparency, that¡¦s why the application of AZO is only limited in few fields. This is because the nature limit of ZnO. Because part of doped Al forms Al2O3 instead of sits on Zn sites, that enhances light and carriers scattering and suppresses the optical transparency and electric conductivity. This study is plane to take advantage of amorphous properties, that may be achieved try grown films at liquid Nitrogen temperature, in which the distribution of Al and Zn will be very uniform and the solubility of Al will be high. ZnO:Al thin films is grown on glass substrates at low temperature by Radio frequency magnetron sputtering system. Low-temperature deposition is done in order to deposit amorphous thin films (ceramic targets ZnO contained 2wt.% Al2O3). The Al3+ in place of Zn2+ should be uniformly distributed in the thin films because of amorphous structure. It expects to find the best deposition condition under a fixed target-to-substrate distance (10cm) by varying growth, such as the deposition mode, PF plasma power and working pressure. AFM, XRD (grazing incident x-ray diffraction) and N&K analyzer were used to measure the thin surface morphology, structure, thickness and transmittance, respectively. The colors of the thin films are very different dependent on the modes of deposition. The low sputtering rate by lower RF power and high working pressure is the key to successfully grow amorphous ZnO:Al films. The amorphous ZnO:Al thin films (a-5) are deposited under 100W of RF power and 50mTorr of working pressure. The transmittance of the assembly of ZnO:Al thin films/glass substrate is the same as glass substrates which inducates the transmittance of films is far above 90%. However, the amorphous ZnO:Al thin films are poor conductor . We also tried to improve it by the post-annealing of ZnO:Al thin films in 2% hydrogen atmosphere. It is found to be not successful.

Submitted by Wagner Henrique Rabelo (wagner144@bol.com.br) on 2018-07-26T20:18:44Z No. of bitstreams: 1 MESTRADO - WAGNER RABELO - VERSÃO FINAL.pdf: 3489307 bytes, checksum: 98e6a7b1b48eed69e255358e3a62fdd9 (MD5) / Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2018-07-30T12:45:51Z (GMT) No. of bitstreams: 1 rabelo_mh_me_bauru.pdf: 3537069 bytes, checksum: 6434660c8d96cc051a92066c85136ebc (MD5) / Made available in DSpace on 2018-07-30T12:45:51Z (GMT). No. of bitstreams: 1 rabelo_mh_me_bauru.pdf: 3537069 bytes, checksum: 6434660c8d96cc051a92066c85136ebc (MD5) Previous issue date: 2018-05-28 / O avanço das técnicas de deposição de filmes finos sobre as superfícies dos materiais tem permitido agregar valor e dar novas funcionalidades aos produtos. Atualmente, os filmes finos de óxido de estanho dopado com índio (ITO) têm encontrado grande aplicação no mercado. Entretanto, devido à pouca disponibilidade do índio na natureza e aos altos custos envolvidos na sua aquisição, elementos alternativos estão sendo estudados para sua substituição. Nesse contexto, destaca-se o óxido de zinco dopado com alumínio (AZO) como um promissor substituto, devido às características de elevada transmissividade, baixa resistividade e band gap da ordem de 3,37 eV, que permitem sua aplicação na síntese de filmes finos semicondutores. Com base no exposto, neste trabalho, foi projetado e desenvolvido o protótipo de uma fonte amplificadora de potência (FAP) de corrente alternada (AC) em baixa frequência, operando entre 15 a 40 kHz, responsável por iniciar e sustentar o campo elétrico utilizado para a geração do plasma. Esta FAP foi utilizada para a deposição de filmes finos de (AZO) por meio da técnica de magnetron sputtering. A análise das características morfológicas, ópticas e elétricas dos filmes de AZO produzidos neste estudo resultaram em uma transmitância superior a 80%, energia de band gap de 3,82 eV, e resistividade de 1,46.10-3 .cm, permitindo concluir que o filme produzido se comporta como um TCO (óxido transparente condutivo). A comparação desses resultados com trabalhos disponíveis na literatura, permite concluir que a fonte amplificadora de potência desenvolvida nesta dissertação possibilita a obtenção de filmes finos de AZO com condutividade e transparência superiores àqueles produzidos com fontes operando em radiofrequência, técnica atualmente disponível e amplamente utilizada no mercado. / The development of thin films deposition techniques allows to increase value and give new features to the materials. Currently, indium doped zinc oxide (ITO) is widely used in the market. However, due to the low availability of the indium in the nature and the high costs involved on its acquisition, alternative elements are being studied for its replacement. Aluminum doped zinc oxide (AZO) stands out as a promising substitute, mainly because of its characteristics, such as high transmissivity, low resistivity and band gap value of 3.37 eV. That allow the application of AZO in the synthesis of thin films semiconductors. In this work, it was developed a prototype of a plasma power source amplifier (FAP) to operate in alternating current (AC) and low frequency (15 - 40 kHz), responsible for initiating and sustaining the electric field used for plasma generation. This FAP was used to deposit AZO thin films by the technique of magnetron sputtering. The analysis of the morphological, optical and electrical characteristics of the AZO films produced in this study resulted in more than 80% transmittance, band gap energy value of 3,82eV, and resistivity of 1,46.10-3 .cm. The thin films synthetized was classified as transparent conductive oxide (TCO). The comparison of these results with the characteristics of similar films avaiable in the bibliography, allows to conclude that the power amplifier source developed in this dissertation makes it possible to obtain thin films of AZO with conductivity and transparency superior to those produced with RF magnetron sputtering, technique currently available and widely used in the market.