Sains Malaysiana 41(8)(2012): 1011–1016

Natural Dye-Sensitized Solar Cell Based on Nanocrystalline TiO₂

(Sel Suria Terpeka Pewarna Semula Jadi Berasaskan Nanohablur TiO₂)

Khalil Ebrahim Jasim*

Department of Physics, College of Science, University of Bahrain

Po Box 32038, Kingdom of Bahrain

Received: 25 January 2010 / Accepted: 7 June 2011

ABSTRACT

During the last quarter of the twentieth century there have been intensive research activities looking for green sources of energy. The main aim of the green generators or converters of energy is to replace the conventional (fossil) energy sources, hence reducing further accumulation of the green house gasses GHGs. Conventional silicon and III-V semiconductor solar cell based on crystalline bulk, quantum well and quantum dots structure or amorphous and thin film structures provided a feasible solution. However, natural dye sensitized solar cells NDSSC are a promising class of photovoltaic cells with the capability of generating green energy at low production cost since no vacuum systems or expensive equipment are required in their fabrication. Also, natural dyes are abundant, easily extracted and safe materials. In NDSSC, once dye molecules exposed to light they become oxidized and transfer electrons to a nanostructured layer of wide bandgap semiconductors such as TiO₂. The generated electrons are drawn outside the cell through ohmic contact to a load. In this paper we review the structure and operation principles of the dye sensitized solar cell DSSC. We discuss preparation procedures, optical and electrical characterization of the NDSSC using local dyes extracted from Henna (Lawsonia inermis L.), pomegranate, cherries and Bahraini raspberries (Rubus spp.). These natural organic dyes are potential candidates to replace some of the man-made dyes used as sensitizer in many commercialized photoelectrochemical cells. Factors limiting the operation of the DSSC are discussed. NDSSCs are expected to be a favored choice in the building-integrated photovoltaics (BIPV) due to their robustness, therefore, requiring no special shielding from natural events such as tree strikes or hails.

Keywords: Building-integrated photovoltaics (BIPV); nanocrystalline layer; natural dye sensitize solar cell NDSSC; photoelectrochemical cell

ABSTRAK

Sejak suku abad yang lalu, aktiviti penyelidikan bagi mencari sumber tenaga hijau sangat giat dilakukan. Matlamat utama penjana atau penukar tenaga adalah untuk menukar sumber tenaga konvensional (fosil) dan mengurangkan pengumpulan gas rumah hijau (GHGs). Sel suria konvensional berasaskan bahan pukal hablur, telaga kuantum dan struktur bintik kuantum atau amorfus dan filem nipis daripada bahan silikon dan semikonduktor III-V menawarkan kemungkinan penyelesaian. Walau bagaimanapun, sel suria terpeka pewarna semula jadi (NDSSC) merupakan kumpulan sel fotovoltan dengan keupayaan penjanaan tenaga hijau pada kos yang lebih rendah disebabkan tiada sistem vakum atau kelengkapan mahal diperlukan untuk penghasilannya. Selain itu, sumber pewarna semula jadi sangat banyak dan ia adalah bahan yang selamat. Di dalam NDSSC, apabila molekul pewarna terdedah kepada cahaya, ia akan teroksida dan memindahkan elektron ke lapisan nanostruktur yang mempunyai jurang tenaga yang lebar seperti TiO2, melalui sentuhan ohmik elektron yang terhasil dikeluarkan dari sel dan terus ke beban. Dalam kajian ini, kami mengkaji struktur dan prinsip operasi sebuah sel suria terpeka pewarna DSSC. Kami membincangkan prosidur penyediaan, pencirian optik dan elektrik sebuah NDSSC menggunakan pewarna tempatan yang diekstrak daripada inai (Lawsonia inermis L.), pomegranat, ceri and rasberi Bahrain (Rubus spp.). Pewarna semula jadi ini merupakan calon yang berpotensi untuk menggantikan sebahagian pewarna buatan manusia yang digunakan sebagai pemeka di dalam sel fotoelektrokimia komersial. Faktor pengehad operasi DSSC juga dibincangkan. NDDSC dijangka menjadi pilihan yang diminati untuk bangunan-terkamir fotovoltan (BIPV) disebabkan kelasakkannya, justeru ia tidak memerlukan perlindungan khusus daripada fenomena semula jadi seperti pukulan pokok dan hujan batu.

Kata kunci: Bangunan-terkamir fotovoltan; lapisan nanohablur; sel fotoelektrokimia; sel suria terpeka pewarna semulajadi

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*Corresponding author; email: khalilej@gmail.com