Colloidal quantum dot (CQD) solar cells (SCs) offer the potential advantages of low cost and flexibility via facile solution processing. However, practical application of CQD SCs is still limited by the relatively short lifetime and low efficiency. The short lifetime is due to the fact that the active spots on CQD surface can readily react with oxygen in ambient. The low efficiency is limited by the trade-off between charge collection and photon harvesting. The research objectives of this proposal include two aspects: (i) to protect CQD film away from ambient oxygen to prolong the lifetime of CQD SCs; (ii) to circumvent the trade-off between charge collection and photon harvesting to improve the efficiency of CQD SCs.In order to realize our research objectives, we carefully propose two promising strategies for each objective. (1) For the first objective, firstly we will grow a stable inorganic semiconductor shell outside CQD core as the protecting layer; secondly, we will fill up the voids in CQD film using stable amorphous n-type TiOx or p-type MoO3 to cut off the way of oxygen attacking the exposed CQD surface. (2) For the second research objective, firstly, we propose to increase electron mobility by incorporating semi-conductive materials, possessing higher electron mobility and lower-lying conduction band (CB) than CQD, into CQD film; secondly, we propose to enlarge the depletion region width by incorporating ferroelectric (FE) material between active layer and anode as interfacial layer.The proposed project aims to address two limitations of CQD SCs. The proposed project falls directly under “Energy Strategy” of the 7th Framework Programme (FP7), which underlines the relevance of the proposed project. The expected results of the proposed project will contribute to European excellence and European competitiveness.