Ambient Stable Perovskite Solar Cells through Trifluoro Acetic Acid-Mediated Multifunctional Anchoring

Abstract

The functional groups of any organic materials play a key role in improving the efficiency and stability of hybrid perovskite solar cells (PSCs). This has led to the use of multifunctional organic molecules for the passivation of perovskites. Herein, trifluoro acetic acid (TFAA) has been reported as an additive for the efficient passivation of perovskite for use in PSC applications. TFAA interacts with perovskites to passivate the defect states and enhance the device performance. The power conversion efficiency (PCE) of the champion device was found to be 20.10%, which improved from 15.08% for the control device without any TFAA. This enhancement resulted due to efficient perovskite passivation, improved crystallinity, and film-forming ability which was confirmed by various studies like density functional theory, Fourier transform infrared spectroscopy, 1 H nuclear magnetic resonance, field emission scanning electron microscopy, atomic force microscopy, and X-ray diffraction. The decrease in defects and trap density was proved by UV−vis, photoluminescence, electrochemical impedance spectroscopy, and other relevant analyses, resulting in better charge generation, reduced recombination, and better charge transport. The fluorinated additive improves the hydrophobicity of the perovskite layer and boosts the ambient stability of the device.

Triple Passivation Approach to Laminate Perovskite Layers for Augmented UV and Ambient Stable Photovoltaics

“…To further investigate the trap passivation and carrier recombination mechanism, impedance spectroscopy (IS) analysis was performed. Figure c depicts the Nyquist plots for pristine and BPT devices recorded at 0.80 V and the graph fitted with an equivalent circuit (inset). , In comparison to the pristine device, the BPT device exhibited a higher recombination resistance ( R rec ) due to minimized recombination and offered better charge transport. Subsequently, trap density of states (t-DOS) was computed from the capacitance values acquired from the IS measurement at varying biases (Figure d). ,, The BPT device showed reduced t-DOS with a narrow distribution corresponding to the pristine device.…”

“…Figure 5c depicts the Nyquist plots for pristine and BPT devices recorded at 0.80 V and the graph fitted with an equivalent circuit (inset). 45,46 In comparison to the pristine device, the BPT device exhibited a higher recombination resistance (R rec ) due to minimized recombination and offered better charge transport. Subsequently, trap density of states (t-DOS) was computed from the capacitance values acquired from the IS measurement at varying biases (Figure 5d).…”

Defect Passivation with Multifunctional Fluoro-Group-Containing Organic Additives for Highly Efficient and Stable Perovskite Solar Cells

“…This is most likely to interact with the positive (Pb 2+ ) and negative (I − ) defects of the perovskite, which is in line with previous reports. 39,60 Further to have detailed information regarding the interaction of these additive molecules with perovskite, XPS was performed (panels c and d of Figure 1). In the case of PFPA, there is significant peak shifts for both Pb (Pb 4f 5/2 and Pb 4f 7/2 ) and I (I 3d 3/2 and I 3d 5/2 ); however, the peak shifts were very slight for the HFBA molecule incorporated perovskite films, confirming that PFPA shows better interaction with perovskite compared to HFBA.…”

“…demonstrated the utility of trifluoroacetic acid (TFAA) for the passivation of perovskite traps and studied its impact on the performance of PSCs. 60 Incorporation of TFAA in perovskite increased the grain size and significantly reduced the nonradiative recombination, which resulted in improved charge transport and device efficiency. Thus, it would be very interesting to see the impact of a higher chain length with more fluorine atoms along with the carbonyl functional group on the defect passivation of perovskite.…”

Perovskite Solar Cells: Assessment of the Materials, Efficiency, and Stability

“…Passivating the perovskite film results in the formation of a hydrophobic film with few defects, good crystallinity, and large grain size. Various research groups have performed FTIR spectroscopy to investigate different solvents, anti-solvents, and additives used during perovskite deposition [114][115][116][117][118]. For example, Garai et al used poly(p-phenylene)-based conjugated polyelectrolytes PHIA functionalized on the side chain to efficiently passivate the trap states in perovskite films [119].…”