Development of Dopant-Free Hole Transport And Passivation Materials For High-Performance Perovskite Solar Cells

Varlıoğlu Yaylalı, Figen
With the rapid increase in interest and remarkable performances achieved by Perovskite Solar Cells (PSCs) in less than 15 years, the primary goal of the researchers has become solving the main critical issue of PSC, long-term stability. To remedy the stability problems, designing different dopant-free transport materials and achieving strong passivation of the perovskite layer have been strongly sought after in the literature. In the first part of the thesis, tetraphenyl silane (HTM 1 and HTM 2), pyrazine (HTM 4), EDOT (HTM 5) and ProTOT (HTM 6) based small molecule hole transport materials were synthesized. These materials were used as dopant-free HTLs in cells with n-i-p architecture (glass/ITO/SnO2/Perovskite/HTM/MoOx/Au). Among them, the best PCE of 16.9% was obtained from dopant-free HTM 4 based-devices. The long-term stability test results showed that devices kept 96% of their initial efficiency for 70 days (room temperature, 15% relative humidity). In the second part, 13 different DPP-based polymers, flanked by different aromatic substituents with varied alkyl chains, were synthesized and their performance in n-i-p devices in glass/ITO/SnO2/Perovskite/HTM/Au architecture was evaluated. Among synthesized polymers, the best PCE of 15.6% was achieved by HTM 12 utilized PSCs. Cells retained 68% of their initial efficiency after four months (room temperature, 15% relative humidity). In the third part of the thesis, six different phenylethyl ammonium-based salts were designed and synthesized via three steps cost-effective methodology with high efficiencies. Three of these salts were then utilized for effective passivation of the perovskite layer with glass/FTO/c-TiO2/m-TiO2/SnO2/Perovskite/X-OMe-PEAI/Spiro-OMeTAD/Au device structure. Among the salts evaluated the best PCE value was found as 23.3% which retained its initial efficiency of 95% for 900 hours under continuous illumination. The performances of the remaining salts were investigated with glass/FTO/SnO2/Perovskite/X-OMe-PEAI/Spiro-OMeTAD/Ag device structure. The best PCE was found as 19.2% which retained 93% of its initial efficiency after six weeks (room temperature, 15% relative humidity).
Citation Formats
F. Varlıoğlu Yaylalı, “Development of Dopant-Free Hole Transport And Passivation Materials For High-Performance Perovskite Solar Cells,” Ph.D. - Doctoral Program, Middle East Technical University, 2023.