Fotovoltaik Hücrelerin Yüzey Morfolojisi ve Verimliliği Üzerinde Termal Tavlama Etkisi

Fotovoltaikler, güneş ışığını elektrik akımına dönüştürür. Bu çalışmada silikon ile yapılan malzemeler yerine elektron verici ve alıcı içeren karışımlar kullanılmıştır. Karbon bazlı organik yarı iletkenlerin işlenmesi kolaydır ve üretim maliyetleri düşüktür. Fotovoltaik cihaz performansında, substrat hazırlama, karışımdaki polimer-alıcı oranları, aktif katmanın termal tavlanması ve üst elektrot biriktirme gibi önemli rol oynayan birkaç üretim adımı vardır. Karışımın nano ölçekli morfolojisinin termal tavlama işlemi ile değiştirilebileceği gösterilmiştir. Sonuç olarak, verim yüzey pürüzlülüğünden etkilenir. İnce filmler ve fotovoltaik hücreler üretmek için donör: alıcı olarak P3HT: PCBM karışımı kullanıldı. Çeşitli zamanlarda tavlanan cihazların güç dönüşüm verimleri ve yüzey morfolojileri ölçülmüştür. Atomik kuvvet mikroskobu (AFM) görüntüleri, aktif tabakanın yüzey pürüzlülüğünün esas olarak tavlama süresinden etkilendiğini ve en pürüzlü yüzeye sahip filmin en verimli güneş pili ile sonuçlandığını ortaya çıkardı.

Anahtar Kelimeler:

AFM, polimerler, fotovoltaikler, termal tavlama

Thermal Annealing Effect on the Surface Morphology and Efficiency of Photovoltaic Cells

Photovoltaics convert solar radiation into electrical current. For the present study, blends containing electron donor and acceptor are used instead of materials made with silicon. Carbon-based organic semiconductors are easy to process and have low fabrication costs. There are several fabrication steps playing important role in the photovoltaic device performance such as, substrate preparation, polymer-acceptor ratios in the blend, thermal annealing of the active layer and top electrode deposition. It has been shown that nanoscale morphology of the blend can be altered via thermal annealing treatment. As a result, efficiency is affected by surface roughness. The blend of P3HT: PCBM as donor: acceptor was used to fabricate thin films and photovoltaic cells. The power conversion efficiencies and surface morphologies of the devices annealed at various times were measured. Atomic force microscopy (AFM) images revealed that the surface roughness of the active layer is mainly affected by the annealing time, and the film with the roughest surface results in the most efficient solar cell.

Keywords:

Atomic force microscopy, polymers, photovoltaics, thermal annealing,

PDF

___

[1] Brabec CJ, Sariciftci NS, Hummelen JC. “Plastic solar cells”, Advanced Functional Materials, 11(1):15-26, (2001).
[2] Hur SW, Kim TW, Chung DH, Oh HS, Kim CH, Lee JU, Park JW. “Organic photovoltaic effects depending on CuPc layer thickness”, Journal of the Korean Physical Society, 45(3):627-9, (2004).
[3] Kang H, Lee W, Oh J, Kim T, Lee C, Kim BJ. “From fullerene–polymer to all-polymer solar cells: The importance of molecular packing, orientation, and morphology control”, Accounts of Chemical Research, 49(11):2424-34, (2016).
[4] Kim FS, Ren G, Jenekhe SA. “One-dimensional nanostructures of π-conjugated molecular systems: assembly, properties, and applications from photovoltaics, sensors, and nanophotonics to nanoelectronics”, Chemistry of Materials, 23(3):682-732, (2011).
[5] Troshin PA, Hoppe H, Renz J, Egginger M, Mayorova JY, Goryachev AE, Peregudov AS, Lyubovskaya RN, Gobsch G, Sariciftci NS, Razumov VF. “Material solubility‐photovoltaic performance relationship in the design of novel fullerene derivatives for bulk heterojunction solar cells”, Advanced Functional Materials, 19(5):779-88, (2009).
[6] Hoppe H, Sariciftci NS. “Morphology of polymer/fullerene bulk heterojunction solar cells”, Journal of Materials Chemistry, 16(1):45-61, (2006).
[7] Zhao Y, Yuan G, Roche P, Leclerc M. “A calorimetric study of the phase transitions in poly (3-hexylthiophene)”, Polymer, 36(11):2211-4, (1995).
[8] Brown PJ, Sirringhaus H, Harrison M, Shkunov M, Friend RH. “Optical spectroscopy of field-induced charge in self-organized high mobility poly (3-hexylthiophene)”, Physical Review B, 63(12):125204, (2001).
[9] Yang X, Loos J, Veenstra SC, Verhees WJ, Wienk MM, Kroon JM, Michels MA, Janssen RA. “Nanoscale morphology of high-performance polymer solar cells:, Nano Letters, 5(4):579-83, (2005).
[10] Anthopoulos TD, Tanase C, Setayesh S, Meijer EJ, Hummelen JC, Blom PW, De Leeuw DM. “Ambipolar organic field‐effect transistors based on a solution‐processed methanofullerene” Advanced Materials, 16(23‐24):2174-9, (2004).
[11] Wöbkenberg PH, Bradley DD, Kronholm D, Hummelen JC, de Leeuw DM, Cölle M, Anthopoulos TD. “High mobility n-channel organic field-effect transistors based on soluble C60 and C70 fullerene derivatives”, Synthetic Metals, 158(11):468-72, (2008).
[12] Rait S, Kashyap S, Bhatnagar PK, Mathur PC, Sengupta SK, Kumar J. “Improving power conversion efficiency in polythiophene/fullerene-based bulk heterojunction solar cells”, Solar Energy Materials and Solar Cells, 91(9):757-63, (2007).
[13] Zen A, Pflaum J, Hirschmann S, Zhuang W, Jaiser F, Asawapirom U, Rabe JP, Scherf U, Neher D. “Effect of molecular weight and annealing of poly (3‐hexylthiophene) s on the performance of organic field‐effect transistors”, Advanced Functional Materials, 14(8):757-64, (2004).
[14] Kim Y, Choulis SA, Nelson J, Bradley DD, Cook S, Durrant JR. “Device annealing effect in organic solar cells with blends of regioregular poly (3-hexylthiophene) and soluble fullerene”, Applied Physics Letters, 86(6):063502, (2005).
[15] Reyes-Reyes M, Kim K, Carroll DL. “High-efficiency photovoltaic devices based on annealed poly (3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6, 6) C 61 blends”, Applied Physics Letters, 87(8):083506, (2005).
[16] Kim H, So W, Moon S. “Effect of thermal annealing on the performance of P3HT/PCBM polymer photovoltaic cells”, Journal of the Korean Physical Society, 48(3):441-5, (2006).
[17] Kim H, Shin M, Kim Y. “Long time thermal annealing effects on the film morphology and performance of polymer solar cells with calcium electrode”, Macromolecular Research, 17(6):445-7, (2009).
[18] Li G, Shrotriya V, Huang J, Yao Y, Moriarty T, Emery K, Yang Y. “High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blends”, In Materials For Sustainable Energy: A Collection of Peer-Reviewed Research and Review Articles from Nature Publishing Group, 80-84, (2011).
[19] Singh I, Madhwal D, Kumar J, Bhatia CS, Bhatnagar PK, Mathur PC. “Effect of thermal annealing on the efficiency of poly (3-hexylthiphone):[6, 6]-phenyl-C 61-butyric acid methyl ester bulk heterojunction solar cells”, Journal of Nanophotonics, 5(1):053504, (2011).
[20] Karagiannidis PG, Kassavetis S, Pitsalidis C, Logothetidis S. “Thermal annealing effect on the nanomechanical properties and structure of P3HT: PCBM thin films”, Thin Solid Films, 519(12):4105-9, (2011).