Progress of Surface Science Studies on ABX<sub>3</sub>‐Based Metal Halide Perovskite Solar Cells

Qiu, Longbin; He, Sisi; Ono, Luis K.; Qi, Yabing

doi:10.1002/aenm.201902726

Cited by 104 publications

(70 citation statements)

References 364 publications

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“…[ 2,18–27 ] However, it is still difficult to accurately identify defect types including Pb 2+ /halide vacancies, interstitial Pb 2+ /halides, and undercoordinated Pb 2+ /halides for these multicomponent perovskites. [ 11,28–30 ] Therefore, identifying defect types and adopting suitable passivators are crucial not only to boost the efficiency but also to slow down the moisture degradation.…”

Section: Introductionmentioning

confidence: 99%

Multifunctional Phosphorus‐Containing Lewis Acid and Base Passivation Enabling Efficient and Moisture‐Stable Perovskite Solar Cells

Yang

Dou

Kou

et al. 2020

Adv Funct Materials

164

139

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Multiple-cation lead mixed-halide perovskites (MLMPs) have been recognized as ideal candidates in perovskite solar cells in terms of high efficiency and stability due to decreased open-circuit voltage loss and suppressed yellow phase formation. However, they still suffer from an unsatisfactory long-term moisture stability. In this study, phosphorus-containing Lewis acid and base molecules are employed to improve device efficiency and stability based on their multifunction including recombination reduction, phase segregation suppression, and moisture resistance. The strong fluorine-containing Lewis acid treatment can achieve a champion PCE of 22.02%. Unencapsulated and encapsulated devices retain 63% and 80% of the initial efficiency after 14 days of aging under 75% and 85% relative humidity, respectively. The better passivation of Lewis acid implies more halide defects than Pb defects at the MLMP surface. This unbalanced defect type results from phase segregation that is the synergistic effect of Cs and halide ion migrations. Identifying defect type based on different passivation effects is beneficial to not only choose suitable passivators to boost the efficiency and slow down the moisture degradation of MLMP solar cells, but also to understand the mechanism of defect-assisted moisture degradation.

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Section: Introductionmentioning

confidence: 99%

Multifunctional Phosphorus‐Containing Lewis Acid and Base Passivation Enabling Efficient and Moisture‐Stable Perovskite Solar Cells

Yang

Dou

Kou

et al. 2020

Adv Funct Materials

164

139

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“…Hole mobility is lower than electron mobility. The performance of PSCs is governed by the balance of charge carrier generation, recombination processes, transport across the bulk, and extraction at the interfaces . The balanced mobility between hole and electron can effectively improve the performance of PSC.…”

Section: Introductionmentioning

confidence: 99%

“…The performance of PSCs is governed by the balance of charge carrier generation, recombination processes, transport across the bulk, and extraction at the interfaces. [7] The balanced mobility between hole and electron can effectively improve the performance of PSC. Therefore, many efforts have focused on the hole transport layer (HTL)/perovskite interface regulation of PSCs to improve the PCE and stabilize PSCs.…”

mentioning

confidence: 99%

Grain Boundary and Interface Passivation with Core–Shell Au@CdS Nanospheres for High‐Efficiency Perovskite Solar Cells

Qin

Wang

et al. 2020

Adv Funct Materials

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The plasmonic characteristic of core–shell nanomaterials can effectively improve exciton‐generation/dissociation and carrier‐transfer/collection. In this work, a new strategy based on core–shell Au@CdS nanospheres is introduced to passivate perovskite grain boundaries (GBs) and the perovskite/hole transport layer interface via an antisolvent process. These core–shell Au@CdS nanoparticles can trigger heterogeneous nucleation of the perovskite precursor for high‐quality perovskite films through the formation of the intermediate Au@CdS–PbI2 adduct, which can lower the valence band maximum of the 2,2,7,7‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)9,9‐spirobifluorene (Spiro‐OMeTAD) for a more favorable energy alignment with the perovskite material. With the help of the localized surface plasmon resonance effect of Au@CdS, holes can easily overcome the barrier at the perovskite/Spiro‐OMeTAD interface (or GBs) through the bridge of the intermediate Au@CdS–PbI2, avoiding the carrier accumulation, and suppress the carrier trap recombination at the Spiro‐OMeTAD/perovskite interface. Consequently, the Au@CdS‐based perovskite solar cell device achieves a high efficiency of over 21%, with excellent stability of ≈90% retention of initial power conversion efficiencies after 45 days storage in dry air.

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“…This is in agreement with results obtained through surface and grain boundaries passivation. [ 26,27 ] Recent theoretical studies have demonstrated a lower formation energy of defects on the surface. [ 28 ] By definition, the surface represents an extended defect, the simple discontinuity will modify the bonds geometry (i.e., lengths and angles) modifying the way carriers will couple to the lattice and their recombination rates as well as the thermodynamic ionization level of defects which will eventually interact with carriers.…”

Section: Defects In Perovskite Solar Cells: Efficiency Versus Stabilitymentioning

confidence: 99%

Defect Tolerance and Intolerance in Metal‐Halide Perovskites

Kim

Petrozza

2020

Advanced Energy Materials

116

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Defect tolerance has been often invoked during the past years to explain the surprising optimal device performance despite the fact we are dealing with a material which can self-assemble at low temperature and is mainly based on ionic bonds. We believe there is not a unique explanation for such observation. One way to understand this phenomenon is understanding the nature of carriers and how they are transported across thin films. So far, there is a general consensus on the nature of photo-carriers, defined as large polarons in 3D perovskites. [9] There have been reports suggesting that such large polarons would be able to screen the carrier-carrier and carrier-defect scattering, thus contributing to the long lifetime of the carriers. [10] Nevertheless, the carrier transport mechanism has not been elucidated yet and the debate on the role of a soft lattice, low energy phonons, and electron-phonon interaction on the screening from defects is still lively. The other side of the medal is looking at the nature of defects and how they will influence the carriers dynamics. We are aware that in perovskite thin films the formation of defects may be strongly influenced by the preparation of perovskite precursors, their processing, crystallization, post treatment procedures and even device operation. Theoretical studies can help to take the right path and understand the intrinsic properties/behaviors of defects. For a first screening on the role of defects on the primary optoelectronic properties of a semiconductor, one has to gather information regarding the probability of forming such defects, the thermodynamic ionization levels of the electronic states they form, and how probable the capture of carriers occurs through an evaluation of the capture cross-section. Density functional theory (DFT) calculations indicate that point defects with the lowest formation energy, mainly vacancies, generally introduce shallow trap states (Figure 1a). For many semiconductors the CB and VB have an antibonding and bonding character. Such a property can bring about deep defect states in the bandgap when an atom is removed. [11] However, in metal-halide perovskites CB and VB both exhibit antibonding character. In MAPbI 3 (MA = CH 3 NH 3 +), VB and CB edges are generated from the interaction between Pb 6s and I 5p orbitals, and Pb 6p and I 5p orbitals, respectively. [12,13] Strong antibonding coupling between Pb 6s orbital and I 5p orbital expands VB bandwidth and raises VB edge, suggesting that most defect states are located within or closer to VB edge. On the other Metal-halide perovskites present exceptional optoelectronic properties such as large light absorption coefficients, long free charge carrier diffusion lengths with ambipolar character. They are apparently protected by what is often described as a "defect tolerance" which has allowed to achieve, relatively quickly, highly performing devices. Nevertheless, there also exists a "defect intolerance" when it is dealt with stability. Further rationalization of the passivation strategi...

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Progress of Surface Science Studies on ABX₃‐Based Metal Halide Perovskite Solar Cells

Cited by 104 publications

References 364 publications

Multifunctional Phosphorus‐Containing Lewis Acid and Base Passivation Enabling Efficient and Moisture‐Stable Perovskite Solar Cells

Multifunctional Phosphorus‐Containing Lewis Acid and Base Passivation Enabling Efficient and Moisture‐Stable Perovskite Solar Cells

Grain Boundary and Interface Passivation with Core–Shell Au@CdS Nanospheres for High‐Efficiency Perovskite Solar Cells

Defect Tolerance and Intolerance in Metal‐Halide Perovskites

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Progress of Surface Science Studies on ABX3‐Based Metal Halide Perovskite Solar Cells

Cited by 104 publications

References 364 publications

Multifunctional Phosphorus‐Containing Lewis Acid and Base Passivation Enabling Efficient and Moisture‐Stable Perovskite Solar Cells

Multifunctional Phosphorus‐Containing Lewis Acid and Base Passivation Enabling Efficient and Moisture‐Stable Perovskite Solar Cells

Grain Boundary and Interface Passivation with Core–Shell Au@CdS Nanospheres for High‐Efficiency Perovskite Solar Cells

Defect Tolerance and Intolerance in Metal‐Halide Perovskites

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Progress of Surface Science Studies on ABX₃‐Based Metal Halide Perovskite Solar Cells