ZnO/CdSe/CuSCN INORGANIC ETA-SOLAR CELLS BASED ON NANOCOLUMNAR ZnO FILMS

摘要

ZnO/CdSe/CuSCN eta (extremely thin absorber)-solar cells based on nanocolumnar ZnO have been successfully realized using easily accessible electrochemical and solution deposition techniques. An n-type ZnO film consisting of free standing single crystal nanocolumns several microns high and 100-200 nm in diameter was deposited on a conducting glass (SnO2:F) substrate covered by a thin spray pyrolysis ZnO electronic blocking layer. A 30-40 nm thin layer of CdSe absorber was electrodeposited coating the ZnO nanocolumns and the voids between the ZnO/CdSe nanocolumns were filled with p-type CuSCN; the entire assembly formed a p-I-n junction. The ZnO/CdSe nanostructure exhibited a high light trapping effect, with an effective absorbance ～ 89% and effective reflectance ～ 8% in the 400-800 nm region of the solar spectrum (AM1.5). In order to measure the photovoltaic characteristics of the eta-solar cells, a gold electrical contact was vacuum evaporated on the CuSCN layer. The measured energy conversion efficiency of 2.3% is the largest value reported for this type of solar cell, showing that the ZnO/CdSe/CuSCN heterostructure is an interesting option for developing new solar cell devices.