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초록

In this study, a di-carboxylic ester additive with a symmetric structure was introduced into perovskite solar cells, and the resulting changes in the optoelectronic properties of the devices were investigated. NMR and DFT analyses revealed that the synthesized additive possesses a nonpolar benzene ring, which is expected to facilitate favorable stacking characteristics. Upon incorporation of this additive, PCE of the devices improved from 10.48% to 11.66%. However, FF decreased from 68.27% to 64.37%. Further analyses, including dark current measurements, light-intensity–dependent current–voltage characteristics, and SCLC fitting, indicated that the additive effectively reduces trap states not only in the perovskite absorber layer but also in the PEDOT:PSS hole transport layer. Therefore, the reduction in FF appears to be attributed not to the formation of traps but rather to a mismatch between the perovskite hole energy level and the elevated quasi-Fermi level of holes in the HTL induced by trap-state reduction. These findings suggest that the additive may exert additional effects, which warrant further investigation.

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