How to Make over 20% Efficient Perovskite Solar Cells in Regular (<i>n–i–p</i>) and Inverted (<i>p–i–n</i>) Architectures

Saliba, Michael; Correa‐Baena, Juan‐Pablo; Wolff, Christian; Stolterfoht, Martin; Phung, Nga; Albrecht, Steve; Neher, Dieter; Abate, Antonio

doi:10.1021/acs.chemmater.8b00136

Cited by 499 publications

(539 citation statements)

References 24 publications

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“…The thickness of the HTM layer is around 150-200 nm, and the uniformity is demonstrated in Figure S6b (Supporting Information), showing a smooth surface and full coverage on top of the perovskite layer. [17] The maximum performance was achieved when adding 4 mol% spiro-OMeTAD(TFSI) 2 , while further increases in the mole fraction caused a drop in PCE, due to lower V OC . Current-voltage (J-V) measurements were undertaken under simulated AM1.5G 1 sun illumination.…”

Section: Resultsmentioning

confidence: 98%

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LiTFSI‐Free Spiro‐OMeTAD‐Based Perovskite Solar Cells with Power Conversion Efficiencies Exceeding 19%

Tan

Raga

Chesman

et al. 2019

Advanced Energy Materials

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To date, the most efficient perovskite solar cells (PSCs) employ an n–i–p device architecture that uses a 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) hole‐transporting material (HTM), which achieves optimum conductivity with the addition of lithium bis(trifluoromethane)sulfonimide (LiTFSI) and air exposure. However, this additive along with its oxidation process leads to poor reproducibility and is detrimental to stability. Herein, a dicationic salt spiro‐OMeTAD(TFSI)2, is employed as an effective p‐dopant to achieve power conversion efficiencies of 19.3% and 18.3% (apertures of 0.16 and 1.00 cm2) with excellent reproducibility in the absence of LiTFSI and air exposure. As far as it is known, these are the highest‐performing n–i–p PSCs without LiTFSI or air exposure. Comprehensive analysis demonstrates that precise control of the proportion of [spiro‐OMeTAD]+ directly provides high conductivity in HTM films with low series resistance, fast hole extraction, and lower interfacial charge recombination. Moreover, the spiro‐OMeTAD(TFSI)2‐doped devices show improved stability, benefitting from well‐retained HTM morphology without forming aggregates or voids when tested under an ambient atmosphere. A facile approach is presented to fabricate highly efficient PSCs by replacing LiTFSI with spiro‐OMeTAD(TFSI)2. Furthermore, this study provides an insight into the relationship between device performance and the HTM doping level.

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Section: Resultsmentioning

confidence: 98%

“…[5,7,17] As shown in Equations (1) and (2), LiTFSI promotes the oxidation of spiro-OMeTAD by O 2 (oxygen), a reportedly slow reaction that is environment dependent [5,7,17] As shown in Equations (1) and (2), LiTFSI promotes the oxidation of spiro-OMeTAD by O 2 (oxygen), a reportedly slow reaction that is environment dependent …”

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confidence: 99%

LiTFSI‐Free Spiro‐OMeTAD‐Based Perovskite Solar Cells with Power Conversion Efficiencies Exceeding 19%

Tan

Raga

Chesman

et al. 2019

Advanced Energy Materials

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“…[26,27] In most cases, the desirable morphology of the perovskite thin-film features a large grain size, a dense film (exhibiting as few pinholes as possible), and a low surface roughness. [29] These strategies, which also play an important role for the coating and printing techniques discussed below, include: a) solvent engineering also called ink formulation engineering, [30][31][32][33][34][35][36] a method that combines solvents of different boiling points to control the solvent evaporation and in turn the crystallization; b) additives [37][38][39][40] in the precursor ink to initiate the crystallization of the perovskite thin-film; c) engineering the composition of the precursor materials to impact the crystallization dynamics (through one-step and two-step deposition routes) [8,10,28,41] ; d) solvent quenching, [8,[42][43][44] by adding so-called antisolvents to the wet film that rapidly remove the ink solvent from the wet film and initiate a prompt crystallization; e) vacuum solvent extraction, similarly using vacuum extraction of the ink solvent from the wet film to prompt crystallization [32,45] ; and f) gas quenching [46,47] and gas drying, [48][49][50] again to push out the solvent from the wet film and assist with rapid crystallization. [7,28] Using the low-throughput, but laboratory-friendly, spin-coating technique, strategies to foster the formation of such high-quality perovskite thin-films have been extensively documented in literature.…”

Section: Introductionmentioning

confidence: 99%

Coated and Printed Perovskites for Photovoltaic Applications

et al. 2019

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optoelectronic devices, a novel lowcost and highly efficient photovoltaic (PV) material emerged. Only 10 years after the first reported perovskite solar cells (PSCs), power conversion efficiencies (PCEs) above 23% were certified, exceeding those of much longer established thin-film PV technologies, including organic photovoltaics (OPV) and inorganic thin-film PV based on copper indium gallium selenide (CIGS) or cadmium telluride (CdTe). [1] The material class of hybrid organic-inorganic perovskites combines excellent optoelectronic properties, such as long diffusion lengths [2] and short absorption lengths, [3] with the ease of solution processing, low energy payback times, and low-cost precursor materials. [4] Moreover, the optoelectronic properties and the material stability can be engineered by varying the constituents in the perovskite crystal structure ABX 3 . For example, the bandgap (E G ) can be tuned by changing the stoichiometric ratio of Br and I at the halogen anion site X. [5][6][7] In order to improve the stability of hybrid organic-inorganic perovskites, compositional engineering of the cation site A was demonstrated to be successful via combining methylammonium (CH 3 NH 3 + or MA + ), formamidinium (CH 5 N 2 + or FA + ), Cs + , and Rb + ions in the so-called multi-cation perovskites. [8][9][10][11] Three key challenges hinder today the economical breakthrough of PSCs:Stability: First, the instability of PSCs against moisture, oxygen, light, and temperature limits the lifetime of PSCs to a fraction of the warranty lifetime (often >25 years) of the market dominating crystalline silicon (c-Si) PV. [12] Very respectable progress has been made over recent years to enhance the stability of PSCs by demonstrating stability over 1000 h, but significant further advances in terms of stability are needed to lift the technology to a level where it is ready to compete with, or be a bolt-on tandem companion to the current PV heavyweight of c-Si. A number of reviews cover recent developments on the topic of stability. [13][14][15][16][17] Toxicity: Second, highly efficient PSCs still contain lead, the toxicity of which hampers the acceptance of the technology and could conflict with legislative barriers. [18] Other recent reviews present progress with respect to this challenge. [19,20] Upscaling: Third, the upscaling of perovskite PV devices to commercial PV module sizes (>1 m 2 ) must be achieved. To date, the vast majority of research and development of PSCs is still Hybrid organic-inorganic metal halide perovskite semiconductors provide opportunities and challenges for the fabrication of low-cost thin-film photovoltaic devices. The opportunities are clear: the power conversion efficiency (PCE) of small-area perovskite photovoltaics has surpassed many established thin-film technologies. However, the large-scale solution-based deposition of perovskite layers introduces challenges. To form perovskite layers, precursor solutions are coated or printed and these must then be crystallized into the perovskite structur...

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“…Recently, power conversion efficiencies (PCEs) close to 24% were demonstrated for perovskite PV, exceeding the PCEs of established thinfilm technologies. [20,24,25] Although these materials result in good performance on short A significant advance toward more stable devices was demonstrated by engineering the composition of the large cation site of the perovskite crystal structure and by including low-dimensional perovskite interlayers and passivation layers.…”

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Electron‐Beam‐Evaporated Nickel Oxide Hole Transport Layers for Perovskite‐Based Photovoltaics

Abzieher

Moghadamzadeh

Schackmar

et al. 2019

Advanced Energy Materials

137

149

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application-oriented research like process engineering and upscaling is observed. [1][2][3][4][5] Even though other optoelectronic devices like light emitting diodes and lasers are being researched, [6][7][8][9][10][11][12][13] perovskite-based photovoltaics (PV) is the key technology driving the fast emergence of perovskitebased optoelectronics. Recently, power conversion efficiencies (PCEs) close to 24% were demonstrated for perovskite PV, exceeding the PCEs of established thinfilm technologies. [14] Despite the rapid progress in terms of PCE, one key challenge of perovskite-based PV is still its low stability under realistic outdoor stress conditions-temperature, humidity, and ultraviolet (UV) radiation. A significant advance toward more stable devices was demonstrated by engineering the composition of the large cation site of the perovskite crystal structure and by including low-dimensional perovskite interlayers and passivation layers. [15][16][17][18][19][20] Further advances in stability are based on the charge extracting materials and their interfaces with the perovskite absorber layers. [21][22][23] Most reported record PCEs are still based on highly expensive organic hole transport layer (HTL) materials like 2,2′,7,7′-tetrakis[N,N-di (4methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-MeOTAD) or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA). [20,24,25] Although these materials result in good performance on short High-quality charge carrier transport materials are of key importance for stable and efficient perovskite-based photovoltaics. This work reports on electron-beam-evaporated nickel oxide (NiO x ) layers, resulting in stable power conversion efficiencies (PCEs) of up to 18.5% when integrated into solar cells employing inkjet-printed perovskite absorbers. By adding oxygen as a process gas and optimizing the layer thickness, transparent and efficient NiOx hole transport layers (HTLs) are fabricated, exhibiting an average absorptance of only 1%. The versatility of the material is demonstrated for different absorber compositions and deposition techniques. As another highlight of this work, all-evaporated perovskite solar cells employing an inorganic NiO x HTL are presented, achieving stable PCEs of up to 15.4%. Along with good PCEs, devices with electron-beam-evaporated NiO x show improved stability under realistic operating conditions with negligible degradation after 40 h of maximum power point tracking at 75 °C. Additionally, a strong improvement in device stability under ultraviolet radiation is found if compared to conventional perovskite solar cell architectures employing other metal oxide charge transport layers (e.g., titanium dioxide). Finally, an all-evaporated perovskite solar mini-module with a NiO x HTL is presented, reaching a PCE of 12.4% on an active device area of 2.3 cm 2 .

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How to Make over 20% Efficient Perovskite Solar Cells in Regular (n–i–p) and Inverted (p–i–n) Architectures

Cited by 499 publications

References 24 publications

LiTFSI‐Free Spiro‐OMeTAD‐Based Perovskite Solar Cells with Power Conversion Efficiencies Exceeding 19%

LiTFSI‐Free Spiro‐OMeTAD‐Based Perovskite Solar Cells with Power Conversion Efficiencies Exceeding 19%

Coated and Printed Perovskites for Photovoltaic Applications

Electron‐Beam‐Evaporated Nickel Oxide Hole Transport Layers for Perovskite‐Based Photovoltaics

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