Probing the energy levels of perovskite solar cells via Kelvin probe and UV ambient pressure photoemission spectroscopy

Harwell, Jonathon R.; Baikie, Tom; Baikie, Iain D.; Payne, Julia L.; Ni, Chengsheng; Irvine, John T. S.; Turnbull, Graham A.; Samuel, Ifor D. W.

doi:10.1039/c6cp02446g

Cited by 102 publications

(118 citation statements)

References 35 publications

(36 reference statements)

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“…It can be used to study the electrical potential distribution across the internal interfaces of inorganic solar cell devices and P3HT:PCBM polymer solar cells . KPFM were also applied to PSCs for studying the local grain boundaries, the internal potential distribution, as well as the energy band diagram . More detailed descriptions of the working principle of KPFM can be found in literature .…”

Section: Methods For Deriving Elamentioning

confidence: 99%

Energy Level Alignment at Interfaces in Metal Halide Perovskite Solar Cells

Wang

Sakurai

Wen

et al. 2018

Adv Materials Inter

242

200

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less than one decade, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) have rapidly been achieved to 22.7%, i.e., a level that is nearly on par with traditional silicon solar cells. [2] In addition, efficient, flexible, [3] color-tunable, and semitransparent PSCs [4] have also been demonstrated, showing the merit for application in portable devices and building-integrated photovoltaics (BIPV). Therefore, PSCs are considered to be the most promising candidate for next-generation high efficiency solar cell technology, and they hold great potential in photovoltaic market in the near future.Perovskite has a general ABX 3 structure. For newly emerged organic-inorganic halide perovskites for photovoltaic application, A represents methylammonium (namely, CH 3 NH 3 + , abbreviated as MA + ), formamidinium (namely, CH(NH 2 ) 2 + , abbreviated as FA + ), and Cs + (including its mixture with MA + and/or FA + ), B represents metal ions, including Pb 2+ and/or Sn 2+ , and X represents halide anions, such as I − , Br − , and Cl − (including the mixture of them). [1f,5] The basic structures of PSCs are shown in Figure 1a. Generally, there are two kinds of structures, namely, mesoporous structure and planar structure. A mesoporous-structured PSC consists of transport conductive oxide (TCO)/compact layer TiO 2 (cl-TiO 2 )/mesoporous layer (TiO 2 or Al 2 O 3 )/perovskite/ hole transport layer (HTL)/metal anode. The planar-structured PSC has an architecture: cathode/electron transport layer (ETL)/ perovskite/HTL/anode for conventional structure or anode/ HTL/perovskite/ETL/cathode for inverted structure. Both of the mesoporous and the planar PSCs are reported to yield high PCE. [6] As can be seen from Figure 1a, a PSC consists of several layers, including electrodes (cathode and anode), absorber layer, and carrier transport layers. The absorber layer is basically metal halide perovskite (such as MAPbI 3 and FAPbI 3 ), [7] mixed metal halide perovskite (such as FA 1−x MA x Pb(I 1−y Br y ) 3 ), [8] or inorganic perovskite (CsPbI 3 ). [9] For the ETL or HTL, it can be either inorganic (such as TiO 2 , SnO 2 , ZnO, CuI, NiO, etc.) [10] or organic material (such as phenyl-C61-butyric acid methyl ester (PCBM), fullerene (C 60 ), 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD), poly(3,4ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), copper(I) thiocyanate (CuSCN), polytriarylamine (PTAA), poly(3-hexylthiophene) (P3HT), etc.). [11] Figure 1b simply shows a schematic representation of the interfaces and the energy levels in a PSC with planar structure (regardless of The rapid progress of organic-inorganic metal halide perovskite solar cells (PSCs) has attracted broad interest in photovoltaic community. A typical PSC consists of anode/cathode, a perovskite layer as absorber, and carrier transport layer(s) (electron/hole transport layer(s)), which are stacked together, resulting in multi-interfaces between these layers. Charge extraction and transport in these solar...

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Section: Methods For Deriving Elamentioning

confidence: 99%

Energy Level Alignment at Interfaces in Metal Halide Perovskite Solar Cells

Wang

Sakurai

Wen

et al. 2018

Adv Materials Inter

242

200

View full text Add to dashboard Cite

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“…These factors include (i) dopant materials employed and its concentration, (ii) environmental conditions under which the film is prepared,[35e,f,58] (iii) chemical interactions with the underneath layer where spiro‐MeOTAD is deposited,[56c,59] (iv) diffusion and phase‐segregation phenomena of dopants in the HTM,[35e,f,42] (v) influence originated from the measurement conditions and techniques, e.g., cyclic voltammetry (CV) performed in electrolyte solution;[2a,60] ultraviolet photoelectron spectroscopy (UPS)[35f,58] performed under vacuum conditions; photoelectron spectroscopy in air (PESA). [60b,61] Fantacci et al employed density functional theory (DFT) calculations to show that increase in oxidized species of spiro‐MeOTAD + leads to a shift of HOMO towards E F . Schölin et al showed a similar effect of p‐doping with increased concentration of LiTFSI dopants, where the pristine spiro‐MeOTAD had a HOMO leading edge at ≈1 eV below E F .…”

Section: Spiro‐meotad Energy Levelsmentioning

confidence: 99%

Recent Advances in Spiro‐MeOTAD Hole Transport Material and Its Applications in Organic–Inorganic Halide Perovskite Solar Cells

Hawash

Ono

2017

Adv Materials Inter

352

336

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2,2′,7,7′‐tetrakis‐(N,N‐di‐4‐methoxyphenylamino)‐9,9′‐spirobifluorene (spiro‐MeOTAD) hole transport material (HTM) is a milestone in the history of perovskite solar cells (PSCs). Proper choice of HTMs is key factor for efficient charge extraction and stability in solar cells. Spiro‐MeOTAD is proven to be the most suitable HTM for testing PSCs due to its facile implementation and high performance. Similarly, spiro‐MeOTAD is receiving attention in other applications other than in solar cells due to its desirable properties. However, spiro‐MeOTAD is under debate regarding the topics of cost‐performance, long‐term stability, degradation issues (induced by temperature, additives, film quality, and environmental conditions), coating technologies compatibility, reliance on additives, and hysteresis. In this review, the advent of spiro‐MeOTAD, and related aforementioned issues about spiro‐MeOTAD are discussed. In addition, spiro‐MeOTAD properties, alternative and new additives, other applications, and new HTMs that is comparable or outperforms spiro‐MeOTAD in PSCs are summarized. In the outlook, the future research directions based on reported results that warrant further investigations are outlined.

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“…We observe that the Fermi levels for the 15, 35, and 120 nm thick perovskite films deposited on PEDOT:PSS (5.02, 5.05, and 5.15 eV, respectively) were strongly influenced by the WF of the PEDOT:PSS (measured at 5.00 eV), i.e., the Fermi level of the perovskite was “pulled” toward that of PEDOT:PSS 40, 41. This implies that the depletion width of the perovskites on PEDOT:PSS extended through the bulk of the film 42.…”

mentioning

confidence: 94%

Control of Interface Defects for Efficient and Stable Quasi‐2D Perovskite Light‐Emitting Diodes Using Nickel Oxide Hole Injection Layer

et al. 2018

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Metal halide perovskites (MHPs) have emerged as promising materials for light‐emitting diodes owing to their narrow emission spectrum and wide range of color tunability. However, the low exciton binding energy in MHPs leads to a competition between the trap‐mediated nonradiative recombination and the bimolecular radiative recombination. Here, efficient and stable green emissive perovskite light‐emitting diodes (PeLEDs) with an external quantum efficiency of 14.6% are demonstrated through compositional, dimensional, and interfacial modulations of MHPs. The interfacial energetics and optoelectronic properties of the perovskite layer grown on a nickel oxide (NiOx) and poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate hole injection interfaces are investigated. The better interface formed between the NiOx/perovskite layers in terms of lower density of traps/defects, as well as more balanced charge carriers in the perovskite layer leading to high recombination yield of carriers are the main reasons for significantly improved device efficiency, photostability of perovskite, and operational stability of PeLEDs.

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Probing the energy levels of perovskite solar cells via Kelvin probe and UV ambient pressure photoemission spectroscopy

Abstract: We present a study of the energy levels present in a perovskite solar cell using Kelvin probe and UV air photoemission measurements. By constructing a detailed map of the energy levels in the system we are able to predict the maximum open circuit voltage of the solar cell.

Cited by 102 publications

References 35 publications

Energy Level Alignment at Interfaces in Metal Halide Perovskite Solar Cells

Energy Level Alignment at Interfaces in Metal Halide Perovskite Solar Cells

Recent Advances in Spiro‐MeOTAD Hole Transport Material and Its Applications in Organic–Inorganic Halide Perovskite Solar Cells

Control of Interface Defects for Efficient and Stable Quasi‐2D Perovskite Light‐Emitting Diodes Using Nickel Oxide Hole Injection Layer

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