Semiconductor Electrodes IX . Digital Simulation of the Relaxation of Photogenerated Free Carriers and Photocurrents Daniel Laser

A digi ta l s imula t ion of the photoprocess at a semiconductor e lectrode is described. The s imula t ion model accounts for photogenerat ion, recombinat ion, and t r anspor t of excess free carr iers wi th in the semiconductor phase. The origin of the photopoten t ia l in the absence of fa radaic cur ren t is elucidated. Quant i ta t ive cur ren t eff iciency-potent ial curves for the photocur ren ts under a va r i e ty of condit ions a re ca lcula ted for n t y p e TiO2 and these a re compared to exper imen ta l results. In previous papers in this series we have in t roduced the use of d igi ta l s imula t ion methods for the t r ea tmen t of semiconductor electrodes. In Ref. (1) the r e l axa t ion of f ree carr iers fol lowing charge injection, wi th and wi thout surface states, was described. In Ref. (2) a method of der iv ing the semiconductor e lectrode char acteristics, equ i l ib r ium or s teady state, at open circuit in the da rk or under constant i l luminat ion, was p re sented. When a semiconductor e lec t rode at equ i l ib r ium and in Contact wi th solut ion is i l luminated , a cer ta in * Electrochemical Society Active Member.