Elucidating the charge carrier separation and working mechanism of CH3NH3PbI3−xClx perovskite solar cells

Edri, Eran; Kirmayer, Saar; Mukhopadhyay, Sabyasachi; Gartsman, K.; Hodes, Gary; Cahen, David

doi:10.1038/ncomms4461

Cited by 545 publications

(538 citation statements)

References 27 publications

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“…Therefore, the FTO layers are the n þ þ electrodes. Reports in literature have shown that some lead halide perovskite solar cells behave as p-i-n cells 3,[16][17][18] . Our lead halide perovskites thin films are highly resistive and have low carrier concentrations, typically below the sensitivity of our Hall measurement system (B10 14 cm À 3 ).…”

Section: Resultsmentioning

confidence: 99%

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

et al. 2015

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Efficient lead halide perovskite solar cells use hole-blocking layers to help collection of photogenerated electrons and to achieve high open-circuit voltages. Here, we report the realization of efficient perovskite solar cells grown directly on fluorine-doped tin oxide-coated substrates without using any hole-blocking layers. With ultraviolet-ozone treatment of the substrates, a planar Au/hole-transporting material/CH 3 NH 3 PbI 3-x Cl x /substrate cell processed by a solution method has achieved a power conversion efficiency of over 14% and an open-circuit voltage of 1.06 V measured under reverse voltage scan. The open-circuit voltage is as high as that of our best reference cell with a TiO 2 hole-blocking layer. Besides ultraviolet-ozone treatment, we find that involving Cl in the synthesis is another key for realizing high open-circuit voltage perovskite solar cells without hole-blocking layers. Our results suggest that TiO 2 may not be the ultimate interfacial material for achieving high-performance perovskite solar cells.

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Section: Resultsmentioning

confidence: 99%

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

et al. 2015

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“…Furthermore, methods such as Kelvin probe force microscopy (KPFM) [148,149] and electron-beam-induced current (EBIC) measurements [150,151] allowed for the measurement of the potential and current distribution within a device, providing more direct evidence for a charge trapping and detrapping process. In these experiments, the charge-carrier-density distribution across the cross-section of the device was measured, allowing one to track the evolution of accumulated charges after illumination.…”

Section: Wwwadvancedsciencenewscommentioning

confidence: 99%

Capturing the Sun: A Review of the Challenges and Perspectives of Perovskite Solar Cells

Petrus

Schlipf

Cheng

et al. 2017

Advanced Energy Materials

317

201

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following statement: These materials can be processed from solution and yet exhibit optoelectronic materials properties described in classic solid-state physics textbooks. This unprecedented combination has led to photovoltaic devices that can be processed at room temperature and achieve performance levels similar to industry giant polycrystalline silicon, from a starting point of 3.8% in 2009. [1][2][3][4] The first light-emitting electrochemical cells [5] and diodes [6][7][8] have also been introduced recently, leading to tunable light emission spectra and internal quantum efficiencies exceeding 15%.The road towards these achievements has been marked by a constant improvement of perovskite deposition techniques fueled by our increasing understanding of the crystallization processes. The choice of deposition technique, either from solution or vapor, and the composition and order in which precursor species are applied has a great influence on the crystallization kinetics. Here, one can distinguish one-step methods where the perovskite is formed from a precursor mixture dissolved in a common solution, and two-step methods where the inorganic compound is deposited first and transformed to the perovskite phase later by addition of the organic constituents. [9][10][11] Furthermore, many parameters during processing can have an effect on the crystallization mechanism and consequently on film morphology, such as the choice of solvents, concentrations and processing additives that are often not incorporated into the final product. [11][12][13] We discuss this aspect in Section 2, where we focus our attention on the most commonly employed solution-based techniques. Additionally, as for any new technology trying to displace an incumbent technology, higher efficiencies, lower costs, reproducibility, stability, and sustainability are paramount. In particular, reproducibility has been a major challenge in perovskite solar cells from the beginning: small variations in morphology, like crystal size, film roughness, and pinholes can have detrimental effects on photovoltaic performance. [14] On the other hand, current-voltage measurements often showed a hysteresis that is rarely seen in other photovoltaic technologies. [15] These topics are highlighted in Sections 3 and 4. Finally, in Section 5 we discuss the framework for market introduction, such as cost reduction by choosing low-cost charge transport layers, or how the lifetime of perovskite absorbers can be extended by the choice of materials composition.Hybrid metal halide perovskites have become one of the hottest topics in optoelectronic materials research in recent years. Not only have they surpassed everyone's expectations and achieved similar performance as tried and true polycrystalline silicon photovoltaic devices, but they are also finding applications in a variety of different fields, including lighting. The main advantages of hybrid metal halide perovskites are simple processability, compatible with large-scale solution processing such as roll-to-roll printing, a...

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“…It has been already reported that CH 3 NH 3 PbI 3 forms two active junctions: one with the n-type TiO 2 and the other with p-type spiro-OMeTAD. 20 The interface between TiO 2 and CH 3 NH 3 PbI 3 shows a huge lattice mismatch. 15 These mismatches produce high electrical capacitance at the interface.…”

Section: ¹2mentioning

confidence: 99%

Origin of the Hysteresis in I–V Curves for Planar Structure Perovskite Solar Cells Rationalized with a Surface Boundary-induced Capacitance Model

Cojocaru

Uchida

Jayaweera³

et al. 2015

Chemistry Letters

109

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For efficient hybrid solar cells based on organometal halide perovskites, the real origin of the IV hysteresis became a big issue and has been discussed widely. In this study, simulated IV curves of different equivalent circuit models were validated with experimental IV curves of a planar perovskite solar cell with the power conversion efficiency (PCE) of 18.0% and 8.8% on reverse scan (from open circuit to short circuit) and forward scan (from short circuit to open circuit), respectively. We found that an equivalent circuit model with a series of double diodes, capacitors, shunt resistances, and single series resistance produces simulated IV curves with large hysteresis matching with the experimentally observed curves. The electrical capacitances generated by defects due to the lattice mismatch at the TiO 2 /CH 3 NH 3 PbI 3 and CH 3 NH 3 PbI 3 /spiro-OMeTAD interface are truly responsible for the hysteresis in perovskite solar cells.Perovskite solar cells based on CH 3 NH 3 PbI 3 have attracted enormous attention in the last few years due to their outstanding performance as photovoltaics. The power conversion efficiency (PCE) of the devices has dramatically improved to over 20% in a relatively short duration.1,2 Despite the unique properties and higher efficiencies, several important issues, e.g., mysterious hysteresis in IV curves and durability of stabilized performance, still remained for commercialization.3,4 It has been found the hysteresis strongly depends on the device architecture, where the planar structure and Al 2 O 3 mesoscopic perovskite cells show relatively large hysteresis than TiO 2 mesoporous structure devices. 5 The typical planar structure of SnO 2 :F(FTO)/compact TiO 2 /CH 3 NH 3 PbI 3 /spiro-OMeTAD/Au 6 suffers from severe hysteresis in the IV measurement.3,4 The reverse scan (from the open circuit to the short circuit) always shows higher PCE than the forward scan (from short circuit to the open circuit). Hence, such hysteresis in the IV curves creates ambiguity about the actual performance of the device, which is being suspected to be over-estimated. 7,8 The origin of hysteresis has been discussed on the intrinsic proprieties like ferroelectric polarization 9 and/or ionic migration 10 of the perovskite to date. However, there was no direct evidence that could support the above claims. It has been reported that passivation of TiO 2 layer by C60 or use of phenyl-C61-butyric acid methyl ester (PCBM) instead of TiO 2 in inverted device structure reduces the hysteresis. 1113 The passivation could minimize the trap states and improve electron transfer through the interface of TiO 2 /CH 3 NH 3 PbI 3 , resulting in the reduction of hysteresis.11 On the other hand, PCBM in the inverted cell could extract the carriers (electrons) more efficiently than TiO 2 without accumulation at the interface, and the hysteresis was eliminated. In another standpoint, lattice mismatch of the interfaces containing organic compounds could be ignored and consequently the hysteresis was reduced. The importance of la...

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Elucidating the charge carrier separation and working mechanism of CH3NH3PbI3−xClx perovskite solar cells

Cited by 545 publications

References 27 publications

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

Capturing the Sun: A Review of the Challenges and Perspectives of Perovskite Solar Cells

Origin of the Hysteresis in I–V Curves for Planar Structure Perovskite Solar Cells Rationalized with a Surface Boundary-induced Capacitance Model

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