Enhance the performance of dye-sensitized solar cells with effective compact layers and direct contact cell structure

Compact layers (CLs) characterized by dense structures play a crucial role in enhancing the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). Previous studies focus on preparing CLs using a single precursor through one-step methods. In this study, the new CLs are prepared by sequentially depositing films using titanium tetrachloride and titanium diisopropoxide bis(acetylacetonate) via chemical bath deposition and spray pyrolysis, respectively. Scanning electron microscope images show that the resulting CL has a denser structure compared to those prepared by one-step methods. Moreover, electrochemical impedance analysis indicates that they can efficiently inhibit charge recombination at the interface, leading to higher PCE. Furthermore, when the CL and direct contact (DC) structure are applied simultaneously to fabricate the DSSCs using Y123 dye and Co^2+/3+ electrolyte, efficiencies of 9.86 % and 24.74 % can be obtained respectively, under one-sun and room light conditions (200 lx). Additionally, tandem cells using the DC structure for both top and bottom cells can achieve an efficiency of 29.68 % under room light illumination of 200 lx.