It's a trap! On the nature of localised states and charge trapping in lead halide perovskites

Jin, Handong; Debroye, Elke; Keshavarz, Masoumeh; Scheblykin, Ivan G.; Roeffaers, Maarten B. J.; Hofkens, Johan; Steele, Julian A.

doi:10.1039/c9mh00500e

Cited by 411 publications

(384 citation statements)

References 159 publications

(199 reference statements)

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“…[ 40 ] This again emphasizes our previous discussion earlier that S doping can passivate defect states by bonding Pb cations in a way to prevent the formation of undercoordinated Pb or I vacancies. [ 41 ] The reduction of defect states also benefits from improved perovskite film quality with S–NiO. Less defect‐induced charge recombination occurred during hole transport and is consistent with our studies on PV devices.…”

Section: Resultssupporting

confidence: 88%

Surface Sulfuration of NiO Boosts the Performance of Inverted Perovskite Solar Cells

Yang

Xiao

et al. 2020

Solar RRL

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As one of the most promising hole‐transporting materials for perovskite solar cells (PSC), NiO is widely used in the inverted p–i–n cell structure due to its high stability, decent hole conductivity, and easy processability for hysteresis‐free cells. However, the efficiency of NiO‐based PSCs is still low, due largely to the poor perovskite/NiO interface. Herein, a sulfur‐doping strategy to modify NiO surface via ion exchange reaction by a simple and scalable chemical bath deposition technique is introduced, which greatly improves the photovoltaic (PV) performance of the derived devices. A systematic investigation is shown where sulfur doping leads to favorable interfacial energetics with a reduced Voc loss. Sulfur doping at the interface also improves the contact between NiO and perovksite and facilitates the formation of high‐quality perovskite films. Carrier dynamics studies demonstrate reduced defect states and trap‐assisted recombination with sulfur doping, which promote the PV performance of the devices. These merits contribute concurrently to low‐loss charge transfer across the perovskite/NiO interface and facilitate charge transport through the perovskite films, leading to a high champion efficiency of 20.43% of the p–i–n structure solar cell devices.

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Section: Resultssupporting

confidence: 88%

Surface Sulfuration of NiO Boosts the Performance of Inverted Perovskite Solar Cells

Yang

Xiao

et al. 2020

Solar RRL

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“…Moreover, by experiments and simulations, it has been shown that Pb off‐centering and tilting angle affect the MAPbI 3 bandgap; namely, an increase of the distortion of the structure brings to a reduction of the energy of the valence band due to the reduction of the (unusual) antibonding overlap between Pb 6s and I 5p atomic orbitals. Indeed, the benign nature of point defects in MHPs has been attributed to the chemical character of the valence band minimum and conduction band maximum orbitals . The above observations bring us to the conclusion that structural distortions induced by GBs might affect the energetics of point defects in the bulk of crystalline grains.…”

Section: Resultsmentioning

confidence: 99%

Defect Dynamics in MAPbI₃ Polycrystalline Films: The Trapping Effect of Grain Boundaries

Mattoni

Meloni

2020

Helvetica Chimica Acta

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Metal halide perovskites, chemical compounds of ABX3 stoichiometry (A=CH3NH3+, Cs+, …; B=Pb2+, Sn2+; X=I−, Br−), have attracted great interest as they emerged as one of the most promising class of materials for low‐cost photovoltaics with over 25 % certified power conversion efficiency. An important open question for further improving their efficiency and stability is the formation and dynamics of point defects, for example, iodide vacancies and interstitials. In particular, recently it has been shown that defects strongly interact with grain boundaries, which, for example, prevents a quick restoration of initial conditions of film when kept in the dark after illumination [Phung et al., Adv. Energy Mater. 2020, 1903735]. It has also been shown that iodide defects may accumulate at grain boundaries, where they induce carriers’ recombination [Park et al., ACS Energy Lett. 2019, 4, 1321–1327]. In this article, we make use of molecular dynamics and ab initio simulations to follow the evolution and compute the energetics of a iodide vacancy, VI• , and an iodide Interstitial, iI' , interacting with Σ5/(102) grain boundaries of different termination, MAI and PbI2. We show that the polarization charge of Σ5/(102) grain boundary associated to a prescribed termination drives the dynamics of charged defects, VI• and iI' . The long‐range interaction of grain boundaries with charged species might induce the accumulation of point defects present in crystallites or formed under operation conditions. Moreover, the selective attraction of specific defects by a grain boundary may help splitting Frenkel pairs formed in solar cells under illumination, thus preventing the quick annihilation of defects and enhancing the effect of light in inducing degradation processes.

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“…It has been established that the stability (under ambient/inert, dark/ light, thermal/room-temperature conditions) of the perovskite layer can be signicantly enhanced through composition engineering of the cation and anion elements, as well as through processing additives, antisolvent engineering and defect management. 99 For example, it has recently been demonstrated that triplehalide tailored MAPbI 2Àx BrCl x PPV devices can sustain over 95% of their initial efficiency under continuous light soaking under 1000 lx FL light for over 2000 h, 51 while MAPbI 3 and MAPbI 2 Br reference devices undergo signicant degradation. This is due to the key role of the small Cl À ions in causing the shrinkage in the perovskite crystal lattice and further retarding ion migration and halide segregation.…”

Section: Stability Of Low Light Opvsmentioning

confidence: 99%

Indoor application of emerging photovoltaics—progress, challenges and perspectives

et al. 2020

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It's a trap! On the nature of localised states and charge trapping in lead halide perovskites

Abstract: The recent surge of scientific interest for lead halide perovskite semiconductors and optoelectronic devices has seen a mix of materials science sub-fields converge on the same “magical” crystal structure.

Cited by 411 publications

References 159 publications

Surface Sulfuration of NiO Boosts the Performance of Inverted Perovskite Solar Cells

Surface Sulfuration of NiO Boosts the Performance of Inverted Perovskite Solar Cells

Defect Dynamics in MAPbI₃ Polycrystalline Films: The Trapping Effect of Grain Boundaries

Indoor application of emerging photovoltaics—progress, challenges and perspectives

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It's a trap! On the nature of localised states and charge trapping in lead halide perovskites

Abstract: The recent surge of scientific interest for lead halide perovskite semiconductors and optoelectronic devices has seen a mix of materials science sub-fields converge on the same “magical” crystal structure.

Cited by 411 publications

References 159 publications

Surface Sulfuration of NiO Boosts the Performance of Inverted Perovskite Solar Cells

Surface Sulfuration of NiO Boosts the Performance of Inverted Perovskite Solar Cells

Defect Dynamics in MAPbI3 Polycrystalline Films: The Trapping Effect of Grain Boundaries

Indoor application of emerging photovoltaics—progress, challenges and perspectives

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Defect Dynamics in MAPbI₃ Polycrystalline Films: The Trapping Effect of Grain Boundaries