Cover Picture: Small 9/2008

The cover picture shows a series–parallel array of single-walled carbon nanotube (SWNT) solar photovoltaic microcells. In this SWNT solar microcell, the directed semiconducting SWNTs are ultrasonically nanowelded onto two asymmetric metal electrodes with high and low work functions, respectively, resulting in a strong built-in electric field in SWNTs for efficient separation of photogenerated electron–hole pairs. Under solar-light illumination, the device shows photovoltaic effects. A high power-conversion efficiency of 12.6% can be achieved by the monolayer SWNT solar microcell. The results demonstrate the great application potential for SWNTs as the photosensitive material of solar cells. For more information, please read the Communication “Nanowelded Carbon-Nanotube-Based Solar Microcells” by C. Chen et al., beginning on page 1313.