Bifunctional Interfacial Regulation with 4‐(Trifluoromethyl) Benzoic Acid to Reduce the Photovoltage Deficit of MAPbI₃‐Based Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs), which have recently achieved more than 25% efficiency, are highly promising candidates for renewable energy generation. However, the interface of these solar cells is not yet fully understood. Herein, we used self-assembled monolayers (SAMs) to regulate the interface of a SnO 2 electron transport layer (ETL) and a common MAPbI 3 perovskite absorber. Three different monolayers indicate that the contiguous terminal groups and charge distribution of their molecules influence interfacial properties and photovoltaic performance. Aligned energy levels, lower surface tension, and higher quality perovskite crystallization were obtained after SAM regulation. Consequently, applying a 4-(trifluoromethyl) benzoic acid (BA-CF 3 ) SAM improved the power conversion efficiency (PCE) of the resulting PSC from 16.84% to 18.67%. Moreover, a high opencircuit voltage (V OC ) of 1.160 V was achieved with significantly reduced defects and non-radiative recombination. This work highlights the regulation of these interfaces by a molecule for achieving high-performance PSCs.

Synergistic crystallization regulation and defect passivation for growth of high-quality perovskite single crystals towards ultrasensitive X-ray detection

“…2b), the –CF 3 peak at 1322 cm −1 for the CF3-PABr/DMF solution is well distinguished compared with MABr/DMF and MAPbBr 3 /DMF solutions. 40 And for the MAPbBr 3 /CF3-PABr/DMF solution, it is noteworthy that the position of the –CF 3 peak shifts to 1324 cm −1 , confirming that the highly electronegative –CF 3 group interacts with Pb 2+ through coulombic/electrostatic interaction. 41 Meanwhile, the peak position of 3328 cm −1 for the MAPbBr 3 /DMF solution and of 3335 cm −1 for the CF3-PABr/DMF solution represents N–H in different chemical environments, which shifts to a higher wavenumber of 3341 cm −1 for the MAPbBr 3 /CF3-PABr/DMF solution, suggesting the interaction of –NH 3 + in CF3-PA + with undercoordinated Br − in the perovskite complex.…”

Challenges in the design and synthesis of self-assembling molecules as selective contacts in perovskite solar cells

“…This was observed in the series of compounds 31-33 where 4-(triuoromethyl)benzoic acid 32 improved the PCE to 18.67% and a high open-circuit voltage (V OC ) of 1.160 V was achieved with a signicant decrease of the defects and non-radiative recombination. 59 Although less common, sulphonic acids can also be promising anchoring groups, as in the case of p-chlorobenzenesulfonic acid 34 which mitigates two of the most adverse problems in NiO x -based inverted perovskites. On one side, the chlorine functional group of 34 promotes perovskite growth, while the sulfonic acid group passivates the surface defects detected in NiO x , reaching a PCE of 21.8%.…”

“…This was observed in the series of compounds 31–33 where 4-(trifluoromethyl)benzoic acid 32 improved the PCE to 18.67% and a high open-circuit voltage ( V OC ) of 1.160 V was achieved with a significant decrease of the defects and non-radiative recombination. 59 …”