Addendum: Tanabe, K. A Review of Ultrahigh Efficiency III-V Semiconductor Compound Solar Cells: Multijunction Tandem, Lower Dimensional, Photonic Up/Down Conversion and Plasmonic Nanometallic Structures. Energies, 2009, 2, 504-530.

Introduction

I have stated in my recent review article [1] that no direct observation of multiple exciton generation (MEG) in the shape of photocurrent extracted from a semiconductor had been made yet. However, there have been indeed a couple of reports on the photocurrent measurements for colloidal II-VI semiconductor compound quantum dot (QD) and polymer-QD composite solar cells and photodetectors to indicate MEG in the QDs, including demonstrations of over-100% external quantum efficiencies [2,3,4]. Particularly, Sukhovatkin et al. have presented a universal spectral quantum efficiency enhancement curve dependent only on bandgap-normalized photon energy consistent among photodetectors with varied PbS QD bandgap energies as a signature of MEG, eliminating potential artifactual explanations for the observed photocurrent enhancement represented by external trap states induced absorption or transitions [5].