Surface Photovoltage Spectroscopy Study of Organo-Lead Perovskite Solar Cells

Barnea-Nehoshtan, Lee; Kirmayer, Saar; Edri, Eran; Hodes, Gary; Cahen, David

doi:10.1021/jz501163r

Cited by 93 publications

(79 citation statements)

References 38 publications

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“…It has been suggested that the V oc in the cell is primarily generated by the electron extraction layer/MAPI contact. 12 If so, then the shift in the CI peak voltage in figure 4b indicates changes in dipole/charge density at the mpTiO 2 / MAPI and/or sTiO 2 /MAPI interfaces. The capacitance in figure 3c, 2 µF/cm 2 , is similar to the capacitance measured for planar TiO 2 films facing electrolyte.…”

Section: Current Interrupt Voltage and Band Offsetsmentioning

confidence: 98%

“…There is also debate about how to correctly measure the recombination and transport times, the charge density, and even the correct measurement of efficiency. [5][6][7][8][9][10][11][12][13][14][15][16][17] The debate about characterization centers on the interpretation of various time constants that can be measured by optical and electrical means. These time constants range from <1 µs to >100 µs.…”

Section: Introductionmentioning

confidence: 99%

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Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

et al. 2015

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We have examined methylammonium lead iodide (MAPI) cells of the design FTO/sTiO 2 / mpTiO 2 /MAPI/Spiro-OMeTAD/Au using fast opto-electronic techniques including transient photovoltage, differential capacitance, charge extraction, current interrupt, and chronophotoamperometry. The data allow several important conclusions regarding the physics and proper characterization of these cells. 1) In mpTiO 2 /MAPI cells there are two kinds of extractable charge stored under operation: a capacitive electronic charge (~0.2 µC/cm 2 ), and another, much larger, charge (40 µC/cm 2 ) which could be the result of dipole realignment, or the effect of mobile ions. The capacitive charge is ~10 times smaller than in mpTiO 2 /dye/SpiroOMeTAD cells with similar mpTiO 2 thickness. 2) Transient photovoltage decays are strongly double exponential with two time constants that differ by a factor of ~5, independent of bias light intensity. We show that the fast decay (~1 µs at one sun) can be assigned to the predominant charge recombination pathway in the cell. We examine and reject the possibilities that the fast decay is due to ferro-electric relaxation, or to the bulk photovoltaic effect. We provide two possible schematic electrical models for the cells that reproduce the V oc and TPV data.3) It has been previously observed that MAPI cells frequently show current/voltage hysteresis. For example, an increase in J sc and V oc is observed on the return sweep of a cyclic JV. Our capacitance vs V oc data indicate that the hysteresis involves a change in internal potential gradients, most likely a shift in band offsets at the TiO 2 /MAPI interface. The TPV results show that the V oc hysteresis is not due to a change in recombination rate constant. Calculation of recombination flux at V oc shows that the hysteresis is also not due to an increase in charge separation efficiency, and that charge generation is not a function of applied bias. We also show that the JV hysteresis is not a light driven effect, but is caused by exposure to forward bias, light or dark.

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Section: Current Interrupt Voltage and Band Offsetsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

et al. 2015

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“…Very recently, the enormous potential for characterization of Kelvin probe has been employed to investigate the role of selective contacts in perovskite solar cells, exploring the surface of the samples. 18 Here, KPFM has been employed for the characterization of the cross-sectional potential distribution in complete devices. Fig.…”

Section: à3mentioning

confidence: 99%

Electrical field profile and doping in planar lead halide perovskite solar cells

Guerrero

Juárez-Pérez

Bisquert

et al. 2014

Applied Physics Letters

179

180

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Hybrid lead halide perovskites (PVKs) have emerged as novel materials for photovoltaics and have rapidly reached very large solar to electricity power conversion efficiencies. As occurring with other kind of solar technologies establishing the working energy-band diagram constitutes a primary goal for device physics analysis. Here, the macroscopic electrical field distribution is experimentally determined using capacitance-voltage and Kelvin probe techniques. Planar structures comprising CH 3 NH 3 PbI 3Àx Cl x PVK exhibit p-doping character and form a p-n heterojunction with n-doped TiO 2 compact layers. Depletion width at equilibrium within the PVK bulk has an extent about 300 nm (approximately half of the layer thickness), leaving as a consequence a significant neutral zone towards the anode contact. Charge collection properties are then accessible relying on the relative weight that diffusion and drift have as carrier transport driven forces. Recently, hybrid lead halide perovskites (PVKs) have reached very large solar to electricity power conversion efficiencies, 1,2 with efficiencies 16%. 3 In the last two years, many different configurations have been analyzed varying cell configuration, selective contacts, and even the kind of perovskite utilized.1,2 Despite this broad range of variations, probably the most extensively studied has been the CH 3 NH 3 PbI 3 perovskite (or its analogous but using chlorine precursor: CH 3 NH 3 PbI 3Àx Cl x ) as absorber materials, in combination with electron (TiO 2 ) and hole (spiro-OMeTad) selective contacts. The organic cation CH 3 NH 3 þ is mainly responsible for the structural stability of the PVK, while the electronic properties are largely determined by metal and halide hybridized orbitals. [4][5][6] In spite of the spectacular advances in cell efficiency, many aspects of this system are not completely understood. One central piece of information for understanding the photovoltaic operation of these solar cells is the energy-band diagram. In general, the band diagram provides key knowledge of several aspects intervening into the working mechanisms of solar cells, namely, the spatial distribution of the macroscopic electrical field within the absorber layer determining charge collection properties; the direction of electrical field and dipole layer at contacts; the local density of electron and hole carrier at each point of the device. Here, we report on characteristic energy features of PVK solar cells based on the combined use of capacitancevoltage ðC À VÞ and Kelvin probe force microscopy (KPFM).Because of the energetic offset between work functions of the absorber and each contact material, it is expected the formation of a built-in voltage V bi in equilibrium conditions. There are several ways to accommodate V bi depending on the electrostatic characteristics of the bulk materials and interfaces. For undoped absorber materials a rather constant electrical field along the whole bulk is expected as occurring for p-i-n structures. However, doping alters the electrical...

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“…5b. As is seen, through 370 to 650 nm, the SPV signal of P3HT NWs:CdSe NTs hybrid device produces an obviously enlarged SPV signals compared to that of the P3HT:CdSe NTs reference, indicative of an increased number of charges that can transport to the hybrid film surface after exciton dissociation [34, 35]. …”

Section: Resultsmentioning

confidence: 99%

Efficient Organic/Inorganic Hybrid Solar Cell Integrating Polymer Nanowires and Inorganic Nanotetrapods

Tan

Liu

et al. 2017

Nanoscale Res Lett

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Constructing a highly efficient bulk-heterojunction is of critical importance to the hybrid organic/inorganic solar cells. Here in this work, we introduce a novel hybrid architecture containing P3HT nanowire and CdSe nanotetrapod as bicontinuous charge channels for holes and electrons, respectively. Compared to the traditionally applied P3HT molecules, the well crystallized P3HT nanowires qualify an enhanced light absorption at the long wavelength as well as strengthened charge carrier transport in the hybrid active layer. Accordingly, based on efficient dissociation of photogenerated excitons, the interpercolation of these two nano-building blocks allows a photovoltaic conversion efficiency of 1.7% in the hybrid solar cell, up to 42% enhancement compared to the reference solar cell with traditional P3HT molecules as electron donor. Our work provides a promising hybrid structure for efficient organic/inorganic bulk-heterojunction solar cells.

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Surface Photovoltage Spectroscopy Study of Organo-Lead Perovskite Solar Cells

Cited by 93 publications

References 38 publications

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

Electrical field profile and doping in planar lead halide perovskite solar cells

Efficient Organic/Inorganic Hybrid Solar Cell Integrating Polymer Nanowires and Inorganic Nanotetrapods

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Surface Photovoltage Spectroscopy Study of Organo-Lead Perovskite Solar Cells

Cited by 93 publications

References 38 publications

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO2: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO2: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

Electrical field profile and doping in planar lead halide perovskite solar cells

Efficient Organic/Inorganic Hybrid Solar Cell Integrating Polymer Nanowires and Inorganic Nanotetrapods

Contact Info

Product

Resources

About

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis