Interfacial Engineering in Functional Materials for Dye-Sensitized Solar Cells

5 Function of Compact (Blocking) Layer in Photoanode

Su Pei Lim^1,2

¹ Xiamen University Malaysia, School of Energy and Chemical Engineering, Jalan Sunsuria, Bandar Sunsuria, Sepang, Selangor Darul Ehsan, Malaysia

² Xiamen University, College of Chemistry and Chemical Engineering, Xiamen, China

5.1 Introduction

Other than the charge recombination, back reaction in dye‐sensitized solar cell (DSSC) is also another major problem for the low efficiency [1,2]. The commonly used porous TiO₂ layer, which is essential to serve the purpose of collecting and transporting photoelectrons, could leave a portion of the transparent conducting oxide (TCO) surface uncovered. This will cause the percolation of redox electrolyte on the TCO surface that permits direct electrochemical reduction of I₃ ⁻ (I₃ ⁻ +2e → 3I⁻), leading to the consumption of the photogenerated electron. Hence, the introduction of a blocking layer is important to prevent electron leakage to increase the overall efficiency of the device [3]. The use of a blocking layer has been shown to increase the solar cell's efficiency [4].

The general principle of the compact layer in DSSC can be described as follows. The compact or dense layer will be deposited as a blocking layer between TCO and photoanode. The deposition of the compact blocking layer will cover the surface of the TCO and could minimize the electron leakage. Furthermore, the compact layer also helps in improving the connectivity among the porous nanoparticles. ...