Fig. 4From: Recent Progress Towards Quantum Dot Solar Cells with Enhanced Optical Absorption a Structure of the quantum dots in a fence barrier (DEFENCE) solar cell. Reprinted with permission from Ref. [62] Copyright (2007) American Chemical Society. b Time evolution of carrier lifetime for the two samples with type II band structures. Excitation intensity is 38 mW/cm2. Reprinted from Ref. [77] with the permission of AIP PublishingBack to article page