| Abstract |
| The photovoltaic properties of perovskite solar cells (PSCs) were investigated by adding graphene oxide (GO) to the electron transport layer of TiO2. The PSCs were fabricated with a glass/FTO/BL-TiO2/meso- TiO2 + GO/perovskite/HTL/Au electrode structure by adding various contents of GO (0.0, 0.3, 0.5 and 0.7 wt%) to the TiO2 layer. To analyze the photovoltaic characteristics and transmittance of the TiO2 layer of the PSCs according to the GO content, solar simulator and ultraviolet-visible-near-infrared spectroscopy were used, respectively. Atomic force microscopy and field emission scanning electron microscope were used to analyze the microstructures of both the TiO2 layer and the perovskite layer. The results of the photovoltaic characteristics indicated that energy conversion efficiency (ECE) was gradually increased to 12.70%, 13.13%, 14.19%, and 12.63% for 0.0, 0.3, 0.5, and 0.7 wt% GO contents, respectively. The highest ECE was observed at a GO content of 0.5 wt%, and a decrease in the ECE was confirmed at higher levels. The increase in ECE was confirmed by measuring short circuit current density (Jsc) and shunt resistance which increased with the GO addition. However, when an excessive amount of GO content was added, a decrease in the ECE was observed, due to the decrease in Jsc by the reduction in transmittance. In particular, an increase in the perovskite crystal size caused an increase in the ECE, due to the increased rms of TiO2 at 0.5 wt% GO. With the 0.7 wt% GO TiO2 layer, the perovskite grain size was decreased by the reduction in rms, and this resulted in a decrease in Jsc and ECE. These results suggest that we might improve the efficiency of perovskite solar cells by adding the proper amount of GO to the TiO2 layer.
(Received April 22, 2019; Accepted June 2, 2019) |
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| Key Words |
| electron transport layer, graphene oxide, perovskite grain, AFM, perovskite solar cells |
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