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www.advmat.de www.MaterialsV N High Effi ciency Quantum Dot Heterojunction Solar Cell O I T Using Anatase (001) TiO Nanosheets A 2 C I N Lioz Etgar,* Wei Zhang, Stefanie Gabriel, Stephen G. Hickey, Md K. Nazeeruddin, U M Alexander Eychmüller, Bin Liu, and Michael Grätzel M O C Quantum dots (QDs) have attracted a lot of attention due and a thickness of ∼ 7 nm, and big nanosheets consist of a side to their tunable bandgap and their high optical absorption length of 60–80 nm and a thickness of ∼ 8 nm. The PbS QDs cross section.[1–3] A variety of research projects attempt to in this heterojunction solar cell act as an absorber and at the integrate QDs into solar cells devices, including nanocrystal same time as a hole conductor, rendering superfl uous the use (NC)-poly mer hybrid solar cells, NC-Schottky solar cells, NC- of an additional p-type material for transporting positive charge sensitized titanium dioxide (TiO2 ) solar cells, and NC hybrid carriers. This simple PbS QD/TiO2 nanosheets heterojunction bilayer solar cells.[4–12] Recently investigations focus on QD solar cell achieved a remarkable short circuit current density heterojunction solar cells, by placing oxide NCs (TiO2 or ZnO) (J sc) of 20.5 mA cm− 2 and a light to electric power conversion as a thin spacer layer between the QDs and the FTO.[13–19] In effi ciency (PCE) of 4.73% under 0.9 sun intensity. This is t