YAE S, FUJITANI M, NAKANISHI I, UETSUJI M, TSUDA R, NAKATO Y
Sol. Energy Mater. Sol. Cells 43(3) 311-318 1996年10月 査読有り筆頭著者
The open-circuit photovoltages (V OC s) of photoelectrochemical (PEC) solar cells, equipped with n-Si electrodes modified with ultrafine platinum (Pt) particles, have been investigated as functions of the Pt-particle density and the post-heat-treatment temperature. Langmuir-Blodgett layers of Pt-colloid particles stabilized by polyvinylpyrrolidone (PVP) are used to control the Pt-particle density on the n-Si electrodes. The ideality factor (n) and the dark saturation current density (j 0 ) are determined from plots of logarithm of the short-circuit photocurrent density versus V OC . The n is unity for all the electrodes, independent of both the Pt density and the heat-treatment temperature, indicating that an ideal n-Si/solution junction is formed. The j 0 decreases and, hence, the V OC increases as the Pt density decreases and also as the post-heat-treatment temperature is decreased. The decrease of j 0 is caused by the decrease in the majority carrier dark current density (j 0n ). In cases where the Pt-modified n-Si electrodes are heat-treated at a low temperature of 150°C or not heat-treated, V OC is in the range of 0.61 to 0.63 V, independent of the Pt density, indicating that minority carrier controlled solar cells are obtained.