Fluoroarene derivative based passivation of perovskite solar cells exhibiting excellent ambient and thermo-stability achieving efficiency &gt;20%

Iyer

2022

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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.

Section: Resultsmentioning

confidence: 99%

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

Iyer

2022

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“…Modification of the transport layer by chemical doping is the most recognized strategy for UV stabilization of the perovskite layer. − One more efficient technique for increasing UV stability is utilizing certain materials with strong UV absorption. − Multifunctional organic molecules having absorption in the UV region can potentially enhance the durability of PSCs under UV irradiation. , Such molecules can simultaneously passivate the defect states and improve device efficiency as well as their long-term stability. − All of these passivation molecules are generally utilized for interface passivation or bulk passivation (by adding in the precursor solution) of perovskites. In most of the reported literature, the surface passivation layer is either coated on top of perovskites or incorporated as a bottom layer.…”

Section: Introductionmentioning

confidence: 99%

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

Choudhury

et al. 2022

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The instability of the perovskite solar cells (PSCs) toward ultraviolet (UV) irradiation and moisture is a limiting factor in terms of commercialization even after achieving excellent power conversion efficiencies (PCEs). Herein, an advanced triple passivation technique has been strategically designed and demonstrated utilizing UV-absorbing 2-benzoylpyridine (BP) molecules as a passivation additive to laminate perovskites and improve PSC stability. Double layers of BP were coated on both sides of the perovskite layer, and the molecule was also incorporated into the precursor solution. This strategy significantly improved the perovskite crystallinity and film quality, lowered the recombination, and enhanced the carrier transport in the PSC. The triple-passivated device exhibited a high PCE of 20.46% with almost negligible hysteresis. Further, passivated large-area (2.5 cm2) devices were also fabricated that demonstrated a PCE of 18.61%. Moreover, the triple passivation approach exhibited impressive UV and ambient stability because it can effectively shield the perovskite layer from UV illumination and moisture.

“…The presence of defects/trap states in the perovskite film causes severe trap-assisted recombination, which leads to a high open-circuit voltage ( V oc ) loss. This V oc loss can be suppressed by passivating the defects present in the perovskite layer. − To enhance the perovskite film quality and reduce trap state, different approaches have been established, such as solvent engineering of precursor solution, development of coating procedure, composition engineering, off-stoichiometric passivation, antisolvent engineering, , utilizing organic molecules in antisolvent, , interface engineering, − and additive engineering. − Among these methods, additive engineering is one of the effective approaches for achieving high-quality perovskite films because of the vast diversity present in their functionality and structure. , D−π–A molecules with −COOH group, phenyl-C61-butyric acid methyl ester (PCBM), and C60-PEG have been added in the antisolvent for defect passivation. , The use of these molecules in antisolvent helps in the passivation of surface defects only. Numerous materials have been investigated as additives in perovskite precursor solution including organic halide salts, metal halide salts, inorganic acids, fullerenes, polymers, and nanoparticles. ,− Many of these additives such as IT-4F, F4TCNQ, PVP (poly(4-vinylpyridine)), polyamic acid and polyimide, fullerene derivatives and ITIC, , organic dye (AQ310), p-type conjugated polymers PBDB-T, and P3HT were able to passivate the defects of perovskite films.…”

Section: Introductionmentioning

confidence: 99%

Additive-Assisted Defect Passivation for Minimization of Open-Circuit Voltage Loss and Improved Perovskite Solar Cell Performance

Afroz

et al. 2021

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Trap state formation in perovskite films during their preparation is a key limitation restricting the device performance and stability of perovskite solar cells. These trap states are generally present at the surface of perovskite films and on grain boundaries and work as charge recombination centers, thereby influencing the device performance. Hence, regulating these detrimental trap states that are susceptible to deformation is vital for improving the solar cell performance. Herein, a unique methodology of trap states passivation has been demonstrated using multiple carboxylic acid-functionalized small aromatic molecules. Three additives, viz., benzene carboxylic acid (BCA), benzene-1,3-dicarboxylic acid (BDCA), and benzene-1,3,5-tricarboxylic acid (BTCA), have been utilized as additives in the precursor solution that reduced trap states in the perovskite films. Perovskite films generated in the presence of these additives strongly influence the charge transfer dynamics and result in improved performance and stability of the devices by lowering the photogenerated charge recombination. BTCA-incorporated devices result in the highest power conversion efficiency (PCE) of 18.30% with a significant improvement in the open-circuit voltage (V oc) to 1075.9 mV (an enhancement of ≈80 mV) compared to the control device. Additionally, the devices also show enhanced thermal stability.