Electron Lifetime and Electron Transport Time Determination of The Device With Pt/PW₁₁ Cs/cellulose as Counter Electrode in DyeSensitized Solar Cells

Platinum is a material commonly used as a counter electrode in dye-sensitized solar cells (DSSCs) because of their excellent catalytic performance and electrical conductivity; however, platinum is an expensive material. Some studies have been conducted to modify Pt-based counter electrodes by adding dopant materials with good conductivity and catalytic properties, such as polyoxometalate. In this paper, we utilize polyoxometalate material, PW<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>Cs, as a dopant of Pt-based counter electrode. Electron lifetime ($\tau_{e}$) and electron transport time $\left(\tau_{t r}\right)$ of the device with $\mathrm{Pt} / \mathbf{P} W_{11} \mathrm{Cs} /$ cellulose as counter electrode and its control are studied through transient photovoltage (TPV) and photocurrent (TPC) measurements. Electron lifetime ($\tau_{e}$) extracted from TPV shows that the device with $\mathbf{P t} / \mathbf{P} W_{11} \mathbf{C s} /$ cellulose has longer $\tau_{e}$ than its control, indicating a slow recombination process. Electron transport time ($\tau_{\text {tr }}$) extracted from TPC shows that the device with $\mathbf{P t} / \mathbf{P} W_{11} \mathbf{C s} /$ cellulose has $\tau_{\text {tr }}$ faster than its control, indicating that the device with $\mathrm{Pt} / \mathrm{PW}_{11} \mathrm{Cs} /$ cellulose performs better than its control. Both TPV and TPC of the device with Pt/PW11Cs/cellulose show better performance than the control, as shown by the enhancement in power conversion efficiency $(\eta)$ from 3.54 percent (control) to 3.76 percent.