High conversion efficiency via multiple exciton generation in quantum

5 High conversion efficiency via multiple exciton generation in quantum dots 

In order to achieve higher photovoltages, the rates of photogenerated carrier separation, transport and interfacial transfer across the semiconductor interface must all be fast compared with the rate of carrier cooling (Boudreaux et al, 1980 Nozik, 1980 Williams and Nozik, 1984). The achievement of higher photocurrent requires that the rate of II (rn) or electron-hole pair multiplication is greater than the rates of 

2 Electron-hole pair (exciton) multiplication in quantum dots 

The formation of multiple electron-hole pairs per absorbed photon in photoexcited bulk semiconductors is a process typically explained by impact ionisation. In this process, an electron or hole with kinetic energy greater than the semiconductor bandgap produces one or more additional electron-hole pairs. The kinetic energy can 

Multiexcitons are detected by several spectroscopic measurements. The first one was to monitor the signature of multiexciton decay dynamics using transient absorption (TA) spectroscopy (Schaller and Klimov, 2004 Ellingson et al, 2005 Schaller et al, 2005b and 2006 Murphy et al, 2006). The magnitude of the photo-induced absorption change at the band edge is proportional to the number of electron- 

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