Quantitative evaluation of electron injection efficiency in dye-sensitized TiO(2) films

The efficiency of electron injection (Φ(inj)) in dye-sensitized nanocrystalline films was studied through transient absorption (TA) and time-resolved microwave conductivity (TRMC) measurements. Here, I show the absolute value of Φ(inj) for several dye-sensitized nanocrystalline films and discuss the relationship between Φ(inj) and the free energy change (-ΔG (inj)) for the injection process. Some systems exhibited lower Φ(inj) values even when -ΔG (inj) was sufficiently large to promote electron injection. Recent experimental findings are used to propose possible explanations for this phenomenon. Quantitative evaluation of Φ(inj) using TA and TRMC will give us new insights for developing high-performance solar cell devices.