All‐Vacuum‐Deposited Stoichiometrically Balanced Inorganic Cesium Lead Halide Perovskite Solar Cells with Stabilized Efficiency Exceeding 11%

Chen, Chien‐Yu; Lin, Hung‐Yu; Chiang, Kai-Ming; Tsai, Wen‐Hui; Huang, Yu‐Ching; Tsao, Cheng‐Si; Lin, Hao‐Wu

doi:10.1002/adma.201605290

Cited by 337 publications

(233 citation statements)

References 43 publications

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“…This indicates that the photons excite electrons and holes out of the inorganic metal halide atoms, which is consistent with the density functional theory (DFT) calculations that the corner interstitial cations, whether organic or inorganic, do not directly contribute to the band-edge states (17). However, the efficiency of the purely inorganic perovskites is currently at ∼11% (18)(19)(20), which is far below 22% of HOIP-based solar cells. This suggests that the presence of organic cation may be the key for achieving high solar cell efficiency.…”

supporting

confidence: 77%

Origin of long lifetime of band-edge charge carriers in organic–inorganic lead iodide perovskites

Chen

Foley

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

163

179

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Long carrier lifetime is what makes hybrid organic-inorganic perovskites high-performance photovoltaic materials. Several microscopic mechanisms behind the unusually long carrier lifetime have been proposed, such as formation of large polarons, Rashba effect, ferroelectric domains, and photon recycling. Here, we show that the screening of band-edge charge carriers by rotation of organic cation molecules can be a major contribution to the prolonged carrier lifetime. Our results reveal that the band-edge carrier lifetime increases when the system enters from a phase with lower rotational entropy to another phase with higher entropy. These results imply that the recombination of the photoexcited electrons and holes is suppressed by the screening, leading to the formation of polarons and thereby extending the lifetime. Thus, searching for organic-inorganic perovskites with high rotational entropy over a wide range of temperature may be a key to achieve superior solar cell performance.organic-inorganic hybrid perovskite | carrier lifetime | photoluminescence | polaron T he record efficiency of hybrid organic-inorganic perovskite (HOIP)-based solar cells has reached above 22% (1-4), which is comparable to that of silicon solar cells. The most dominant contribution to the high photovoltaic performance of HOIPs comes from their long carrier lifetimes (≥ 1 μs), which translates to large carrier diffusion lengths despite their modest charge mobilities (5). Several microscopic mechanisms behind the unusually long carrier lifetime have been proposed, such as formation of ferroelectric domains (6-9), Rashba effect (10-12), photon recycling (13), and large polarons (14-16). When the HOIPs are replaced with all inorganic perovskites in the solar cell architecture, the device can still function as a solar cell. This indicates that the photons excite electrons and holes out of the inorganic metal halide atoms, which is consistent with the density functional theory (DFT) calculations that the corner interstitial cations, whether organic or inorganic, do not directly contribute to the band-edge states (17). However, the efficiency of the purely inorganic perovskites is currently at ∼11% (18-20), which is far below 22% of HOIP-based solar cells. This suggests that the presence of organic cation may be the key for achieving high solar cell efficiency. It is, however, yet to be understood how the organic cations enhance the efficiency.Among the aforementioned microscopic mechanisms, three are based on the role of organic cations. First, in the ferroelectric domain theory, nanoscale ferroelectric domains are formed due to alignment of organic cations (6-9). Such domains can spatially separate the photoexcited electron and holes and thereby reduce their recombination. Second, in the Rashba effect theory (10-12), the spin and orbit degrees of freedom of the inorganic atoms are coupled with the electric field generated by the organic cations. This results in the electronic band splitting for different spins and leads to an effectively in...

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supporting

confidence: 77%

Origin of long lifetime of band-edge charge carriers in organic–inorganic lead iodide perovskites

Chen

Foley

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

163

179

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“…[24,29] All these reports suggested that the up to 260 C or even higher temperature was almost necessary for fabricated high performance allinorganic CsPbX 3 perovskite. However, such high annealing temperature would affect the fabrication of all-inorganic perovskite and limit their application, rendering the conversion impractical for many device architectures and substrates, such as temperature sensitive polymer substrate and c-Si solar cells relevant for tandem cell applications.…”

mentioning

confidence: 99%

“…Generally, the yellow-to-black phase transformation occurs at temperatures of above 300 C. [23][24][25][26] A recent investigation on the crystal behavior of CsPbI 3Àx Br x prepared by one step method indicated that the phase-pure CsPbI 2 Br can be obtained only the annealing temperature exceeds %260 C. [27] Similarly, in 2-step method to fabricate all-inorganic perovskite, the phase-pure all-organic perovskite can be acquired when the film annealed at 250 C for 10 min and then an additional 3 min at 350 C. [28] Besides, the gas-assisted and allvacuum-deposited all-inorganic CsPbI 2 Br also need the subsequent >320 C annealing process. [24,29] All these reports suggested that the up to 260 C or even higher temperature was almost necessary for fabricated high performance allinorganic CsPbX 3 perovskite. However, such high annealing temperature would affect the fabrication of all-inorganic perovskite and limit their application, rendering the conversion impractical for many device architectures and substrates, such as temperature sensitive polymer substrate and c-Si solar cells relevant for tandem cell applications.…”

mentioning

confidence: 99%

“…Obviously, the absorption edge of our low temperature prepared CsPbI 2 Br film using 2CsIþHPbI 3þx þPbBr 2 precursor is about 679 nm, which is consisted with the previously reported absorption values for α-CsPbI 2 Br. [27,29] While the typical anti-solvent method prepared CsPbI 2 Br films exhibited the absorbance edge at %450 nm, a signal of δ phase. [32] Figure 1c listed XRD patterns of our low temperature fabricated red brown CsPbI 2 Br thin films and the peaks at 2θ ¼ 14.6, 29.3, and 20.8 are assigned to the (100), (200), and (110) planes of cubic α phase pure CsPbI 2 Br.…”

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confidence: 99%

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A Facile Low Temperature Fabrication of High Performance CsPbI₂Br All‐Inorganic Perovskite Solar Cells

et al. 2017

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All-inorganic lead halide perovskites α-CsPbI 2 Br with higher thermal stability and phase stability are promising candidate for optoelectronic application such as photovoltaics. However, the >250 C high temperature annealing is required to obtain the desired photovoltaic active perovskite phase of α-CsPbI 2 Br, which makes it difficult for fabrication and application based on flexible polymer substrate. Here, a facile formation of high performance allinorganic CsPbI 2 Br perovskite solar cell is reported, through a one-step method and a 100-130 C low temperature annealing process. The faciledeposited CsPbI 2 Br film demonstrates long-term phase stability at room temperature for a month and exhibits the thermal stability under 100 C annealing for more than a week. Consequently, the CsPbI 2 Br-based allinorganic perovskite solar cells (PSCs) exhibit power conversion efficiencies (PCE) of up to a record value of 10.56%. This low temperature crystallization of all-inorganic CsPbI 2 Br perovskite is a promising approach for scalable, convenient, and inexpensive fabrication in the future.Organic-inorganic hybrid lead halide perovskites have emerged as one class of most promising optoelectronic materials for various application due to their excellent optical absorption, good carrier mobility, and lifetime. [1][2][3][4] The power conversion efficiency (PCE) of organic-inorganic hybrid halide perovskite solar cells has progressed rapidly from unstable 3.8% to a certified 22.1% and their stability has also been significantly improved in a relatively short span of time, which make them promising for commercialization. [5][6][7][8] With the progress of these organic-inorganic hybrid perovskite, all-inorganic halide perovskite has demonstrated to be another promising novel alternative candidate for various optoelectronic applications. [9][10][11][12][13][14][15] These allinorganic lead halide perovskites of CsPbX 3 (X ¼ I, Br, Cl) have advantage of higher thermal stability over the well-studied organic-inorganic hybrid lead halide perovskites, such as MAPbX 3 (X ¼ I, Br, Cl). [16][17][18] The excellent thermal stability of all-inorganic lead halide perovskites can be ascribed to the absence of volatile organic component and the higher formation energy. [19] The high formation or crystallization energy helps enhance the thermal stability of CsPbX 3 perovskite but also induces the difficulty for fabrication. Now, CsPbX 3 -based perovskite can be either fabricated via a generally solution-process similar to the hybrid lead halide perovskites or advanced vacuum deposition. [20] Regarding on the solution-process, most reported CsPbX 3 exhibits a yellow orthorhombic phase upon formation at low temperature, which is unsuitable for solar cell applications. [21,22] Followed by a second-high temperature annealing, these yellow phases can form a black cubic perovskite phase. Generally, the yellow-to-black phase transformation occurs at temperatures of above 300 C. [23][24][25][26] A recent investigation on the crystal behavior of CsPb...

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“…However, a Pb-free solution with the high PCE has not been obtained to date. To improve short-term and long-term stabilities, several modifications were made to the device structure and processing methods [23,24]. As of November 2017, researchers from Korea Research Institute of Chemical Technology hold the record PCE for a single-junction PSC with 22.7% [25].…”

Section: Introductionmentioning

confidence: 99%

Rietveld refinement of the crystal structure of perovskite solar cells using CH3NH3PbI3 and other compounds

Ando¹,

Ohishi²,

Suzuki³

et al. 2018

AIP Conference Proceedings

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All‐Vacuum‐Deposited Stoichiometrically Balanced Inorganic Cesium Lead Halide Perovskite Solar Cells with Stabilized Efficiency Exceeding 11%

Cited by 337 publications

References 43 publications

Origin of long lifetime of band-edge charge carriers in organic–inorganic lead iodide perovskites

Origin of long lifetime of band-edge charge carriers in organic–inorganic lead iodide perovskites

A Facile Low Temperature Fabrication of High Performance CsPbI₂Br All‐Inorganic Perovskite Solar Cells

Rietveld refinement of the crystal structure of perovskite solar cells using CH3NH3PbI3 and other compounds

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All‐Vacuum‐Deposited Stoichiometrically Balanced Inorganic Cesium Lead Halide Perovskite Solar Cells with Stabilized Efficiency Exceeding 11%

Cited by 337 publications

References 43 publications

Origin of long lifetime of band-edge charge carriers in organic–inorganic lead iodide perovskites

Origin of long lifetime of band-edge charge carriers in organic–inorganic lead iodide perovskites

A Facile Low Temperature Fabrication of High Performance CsPbI2Br All‐Inorganic Perovskite Solar Cells

Rietveld refinement of the crystal structure of perovskite solar cells using CH3NH3PbI3 and other compounds

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A Facile Low Temperature Fabrication of High Performance CsPbI₂Br All‐Inorganic Perovskite Solar Cells