Introduction of nanocarbon materials into bulk heterojunction hybrid solar cells based on colloidal CdSe quantum dots and conjugated polymers Abstract: Solution processed solar cells based on organic–inorganic hybrid materials have been developed as an alternative route towards low cost fabrication high efficiency light weight and flexible large area devices. Hybrid solar cells are in principle comparable to that of organic solar cells; the only difference is that inorganic semiconductor quantum dots (QDs) are used as electron acceptors instead of fullerene derivatives such as PCBM. However this type of solar cells reported thus far generally suffers from a low power conversion efficiency (PCE) and poor device long term stability. These problems mainly originate from the limitation in electron conductivity and mobility of hybrid solar cells. Hence the design of a more continuous electron transport pathway combined with environmental stability should greatly enhance the performance of hybrid solar cells. In this context nanocarbon based materials such as CNTs and graphene which possess excellent environmental stability and high charge mobility are ideal organic compounds to be combined with inorganic semiconductor QDs. In this thesis functionalized nanocarbon materials graphene oxide (GO) and carbon nanotubes (CNTs) were combined with CdSe QDs to form a novel hybrid nanocarbon CdSe QDs solar cell. The hybrid materials were successfully utilized in a photoactive layer of hybrid solar cells resulting in remarkable long term stability improvement. About 85 % of the original PCE remained after storage in a glove box for one year without any further encapsulation. In addition a modified anode of a hybrid solar cell has been performed by incorporating solution processable reduced GO (rGO) between transparent indium tin oxide (ITO) and poly(3 4 ethylenedioxythiophene):poly(4 styrenesulfonate) (PEDOT:PSS) layers. The device with a GO buffer layer thermally reduced at ambient atmosphere exhibited a remarkable improvement in PCE compared to devices without any interfacial layer indicating that rGO can effectively decrease charge recombination processes by facilitating efficient hole collection