Effect of the length of anodically grown titania nanotubes on the efficiency of a moisture-stable hole transport material (HTM)-free perovskite solar cell

A simple and facile means of developing a cost-efficient, easily reproducible perovskite solar cell (PSC) is presented in this report. This hole transport material (HTM)-free perovskite solar cell is based on electrochemically anodized titania nanotubes which enact the role of an electron transport layer in the defined configuration. The complete procedure involved in the fabrication of the PSC module is carried out under ambient air conditions depicting the moisture resilient nature of the designed module. The fundamental concept, however, relies upon understanding the effect of the length of the grown nanotubes on the efficiency of the PSC constructed with them. The dimensional (length) modulation is carried out by varying the anodizing voltage applied during the growth of the titania nanotubes as well as the anodization methods involved. The structural changes related to the morphology and dimensions of the grown nanotubes were confirmed with X-ray diffraction analysis and field emission scanning electron microscopy, while its effect on the optoelectrical properties was studied using UV-diffuse reflectance spectroscopy and photoconductivity measurements. Finally, PSC modules composed of these nanotube samples were constructed and the effective changes in their efficiency were determined. The current investigation detects an increase in the efficiency of the PSC module with increase in the length of the anodically grown titania nanotube, reiterating the importance of the thickness of the mesoporous layer in the performance of the PSC.