Synthesis and Application of Organic Hole Transporting Materials for Perovskite Solar Cells at Doped-Free Condition

Document Type : Original Article

Authors

1 Department of Chemistry- University of Isfahan, Isfahan

2 Department of Chemistry-University of Isfahan-Isfahan

3 Department of Chemistry- University of Isfahan-Isfahan

Abstract

In recent years, numerous efforts have been made to synthesize new hole-transporting materials for perovskite solar cells with the aim of replacing spiro-OMeTAD. However, to improve the conductivity and mobility of these materials, chemical additives are mostly used, which not only increase the cost but also reduce the stability and efficiency of perovskite solar cells in the long term due to the moisture sensitivity of perovskite crystals. Therefore, small organic molecules 2 and 6 were synthesized using cost-effective raw materials to improve the synthesis route, solubility and morphology on the perovskite surface compared to spiro-OMeTAD for additive-free hole transport materials. The chemical properties, purity, and identification of these molecules were confirmed using electrochemical methods, UV-Vis spectroscopy, and NMR spectroscopy. Due to the donor-acceptor type π-system, the molecules used increase the charge transfer mobility and thus reduce the use of chemical additives. The photovoltaic parameters of the solar cell made from hole transport material 2 and 6 were determined by photovoltaic analysis, and the results showed that the performance of hole-transporting layer 6 was almost the same as of spiro-OMeTAD in additive-free conditions, with a current density of 14.68 mA/cm², an open-circuit voltage of 0.82 V, a fill factor of 0.65, and a power conversion efficiency of 7.88%.

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