Low temperature processable ultra-thin WO3 Langmuir-Blodgett film as excellent hole blocking layer for enhanced performance in dye sensitized solar cell

• Published in: Electrochimica acta 2019-09, Vol.318, p.405-412
• Main Authors: Prakash, Om, Saxena, Vibha, Choudhury, Sipra, Tanvi, Singh, Ajay, Debnath, A.K., Mahajan, A., Muthe, K.P., Aswal, D.K.
• Format: Article
• Language: English
• Subjects: Carrier mobility; Circuits; Dye sensitized solar cells; Dyes; Hole blocking Layer; Langmuir-Blodgett films; Low temperature; Low temperature crystalline WO3; Morphology; Multilayers; Performance enhancement; Photovoltaic cells; Short circuit currents; Thermal stability; Thin films; Titanium dioxide; Transport; Tungsten oxides; Work functions
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2019.06.047

The hole-blocking and electron- transporting layer is an important component of third-generation solar cells. This layer is responsible for both hindering the hole recombination from the hole-transport layer and collecting photo-generated electrons; that in turn impact photon-to-current conversion efficiency (ɳ) of devices. Conventionally, WO3 is being used as hole-transport layer owing to high work function and carrier mobility; and excellent thermal stability. In this paper we report ultra-thin WO3 films, prepared by UVO-treatment of WO3-octadecylamine Langmuir-Blodgett multilayers, for use as blocking layers in dye sensitized solar cells (DSSCs). For the first time, it is observed that ɳ of DSSCs with optimized WO3 blocking layer improved significantly (21%) as compared to those based on conventional TiO2 blocking layers. The improvement in ɳ is the result of improved short-circuit current density which is obtained without any accompanying reduction in open-circuit potential and fill factor. This is attributable to the dense and uniform morphology, excellent hole-blocking properties, crystallinity and proper position of Fermi level. The analyses not only reveal that ɳ of DSSCs can be enhanced by employing ultra-thin WO3 LB films as blocking layers but also suggest that the films can possibly be extended further for perosvskite and polymer solar cells. [Display omitted]