The new emerging organometal trihalide perovskite holds great potential for high-efficiency, low-cost solar cells because of its high solar to electricity conversation efficiency (>16%) achieved within 4 years of research and its low-temperature solution processing. In this Letter we introduce NiO as the hole-collecting and -conducting layer in perovskite solar cells. Through a modified sequential deposition strategy, we successfully fabricated high-quality CH 3 NH 3 PbI 3 onto a planar NiO layer and built a planar inverted ITO/NiO/CH 3 NH 3 PbI 3 / PCBM/Al photovoltaic device. A device efficiency of 7.6% was achieved with an impressively high open-circuit voltage (V oc) of 1.05 V. Our study demonstrates the potential application of a deep work function NiO layer for perovskite solar cells. H igh-efficiency, low-cost solar cells are the everlasting pursuit of photovoltaic research. Very recently, organo-metal halide perovskite has attracted tremendous research attention because of its potential to realize this goal. First introduced in 2009 by Miyasaka's group as the sensitizer for dye-sensitized solar cells (DSSCs) using liquid electrolyte,