Origin of Open‐Circuit Voltage Enhancements in Planar Perovskite Solar Cells Induced by Addition of Bulky Organic Cations

Lin, Chieh‐Ting; Lee, Jinho; Macdonald, Thomas J.; Ngiam, Jonathan; Xu, Bob; Dabóczi, Mátyás; Xu, Weidong; Pont, Sebastian; Park, Byoungwook; Kang, Hongkyu; Kim, Jinhyun; Payne, David J.; Lee, Kwanghee; Durrant, James R.; McLachlan, Martyn A.

doi:10.1002/adfm.201906763

Cited by 57 publications

(57 citation statements)

References 59 publications

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“…The increased Fermi level near the surface of perovskites should benefit from the passivated hole traps at crystal boundaries and would facilitate the efficient holes transport in the devices. [ 39–41 ] Furthermore, the existence of Crown on the surface of perovskite films would well reduce the surface hydrophilicity of FACsPbI 3 perovskite films consistent with the previously reported work, [ 31 ] and also verified by the enlarged water contact angle of 76.8° compared with 65.8° in bare FACsPbI 3 film in a short time (Figure 3f; Video S1, Supporting Information).…”

Section: Resultssupporting

confidence: 88%

Crown Ether‐Assisted Growth and Scaling Up of FACsPbI₃ Films for Efficient and Stable Perovskite Solar Modules

Chen

Wang

et al. 2020

Adv Funct Materials

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FACs‐based (FA+, formamidinium and Cs+, cesium) perovskite solar cells have gained great attention due to their remarkable light and thermal stabilities toward practical application of perovskite modules. However, the moisture instability and difficulty in scalable fabrication are still the main obstacles blocking their photovoltaic applications in current status. Here, the employment of novel interaction between crown ether with metal cations is introduced to tailor the uniform growth and inhibit moisture invasion during the crystallization of α‐phase FACsPbI3, yielding the successful synthesis of high‐quality perovskite films in a large scale. Consequently, perovskite solar cells (PSC) modules in the total area of 4 × 4 and 10 × 10 cm2 are readily fabricated with respective champion efficiencies of 16.69% and 13.84% and excellent stability over 1000 h. This facile scaling‐up strategy assisted by crown ether has shown great promise for pursuing efficient and highly stable large‐area PSC modules.

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Section: Resultssupporting

confidence: 88%

Crown Ether‐Assisted Growth and Scaling Up of FACsPbI₃ Films for Efficient and Stable Perovskite Solar Modules

Chen

Wang

et al. 2020

Adv Funct Materials

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“…Consequently, the shifts in both W f,air and valence band of P2 films indicate the surface‐anchored PMAI dipoles could significantly change the surface states of perovskite films. [ 47,48 ]…”

Section: Figurementioning

confidence: 99%

Superior Carrier Lifetimes Exceeding 6 µs in Polycrystalline Halide Perovskites

et al. 2020

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such as charge-carrier lifetimes and diffusion lengths in perovskite films should be maximized, which are sensitive to the density of sub-bandgap trap states acting as nonradiative recombination centers. [12,13] Long carrier lifetimes and diffusion lengths imply a reduction in trap densities constituted by multidimensional defects that can be broadly observed at the grain boundaries and surfaces of polycrystalline perovskite films. Therefore, defect modulation to efficiently suppress the undesired nonradiative recombination pathways in perovskite films have resulted in dramatically enhanced carrier lifetimes and diffusion lengths, which can be translated into higher open-circuit voltage (V OC) of photovoltaic devices. [14-18] Recently, surface post-treatments, such as depositing a layer of ammonium salts onto the perovskites, are the most frequently employed strategies, passivating the defects in the topmost area of the perovskite films. [19-22] However, the additional depositing procedure is considered to bring much uncertainty to the original perovskite films. [23,24] Recently, Yoo et al. demonstrated that the commonly used solvents (e.g., isopropanol) for dissolving ammonium salts, due to their strong polarity, had negative effects on the underlying perovskite films. [25] Lead halide perovskite films have witnessed rapid progress in optoelectronic devices, whereas polycrystalline heterogeneities and serious native defects in films are still responsible for undesired recombination pathways, causing insufficient utilization of photon-generated charge carriers. Here, radiationenhanced polycrystalline perovskite films with ultralong carrier lifetimes exceeding 6 μs and single-crystal-like electron-hole diffusion lengths of more than 5 μm are achieved. Prolongation of charge-carrier activities is attributed to the electronic structure regulation and the defect elimination at crystal boundaries in the perovskite with the introduction of phenylmethylammonium iodide. The introduced electron-rich anchor molecules around the host crystals prefer to fill the halide/organic vacancies at the boundaries, rather than form low-dimensional phases or be inserted into the original lattice. The weakening of the electron-phonon coupling and the excitonic features of the photogenerated carriers in the optimized films, which together contribute to the enhancement of carrier separation and transportation, are further confirmed. Finally the resultant perovskite films in fully operating solar cells with champion efficiency of 23.32% are validated and a minimum voltage deficit of 0.39 V is realized. Polycrystalline halide perovskites are of enormous excitement to be applied in highly efficient solar cells, [1-3] light-emitting diodes, [4] lasers, [5,6] and high-sensitivity photodetectors [7,8] due to their low fabricating costs [9,10] and excellent optoelectronic properties. [11] In order for these optoelectronic devices to access their theoretical performance limits, key metrics

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“…Currently, the most commonly used perovskite is MAPbI 3 and PSCs using this absorber can now achieve over 20% in PCE. [15,[121][122][123] However, as discussed in Section 2, the hygroscopic nature and high temperature vulnerability of MAPbI 3 makes it more difficult to prepare in ambient conditions and thus making scale up for commercialization unlikely. [84] For example, it was reported that MAPbI 3 undergoes a phase transition between ordered tetragonal and disordered cubic structure at around 57 °C.…”

Section: Composition Engineeringmentioning

confidence: 99%

“…Although the poly(triaryl amine)-based polymers are air stable, [291][292][293] have favorably high water-contact angels, [290] and can produce high efficiency PSCs, [36,123] their complex synthesis and high cost is still a limiting factor. In contrast, nickel oxide (NiO) is an alternative HTM which retains high chemical stability, hole mobility, low cost, and is simple to synthesize.…”

Section: Hole Transport Layermentioning

confidence: 99%

Ambient Fabrication of Organic–Inorganic Hybrid Perovskite Solar Cells

et al. 2020

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Unlike fossil fuels, the sun is an inexhaustible energy source that delivers more energy to the earth in 1 h than the entire planet consumes in one year. Energy can be harvested from the sun using photovoltaics (PV) and stored (e.g., batteries), meaning solar energy can be used as and when required. [3,4] Currently, the commercial PV market is dominated by single-junction crystalline silicon (c-Si) PV which deliver power conversion efficiencies (PCE) of over 26% under 1 Sun illumination (AM 1.5 standard). [5,6] Despite their high efficiencies, the fabrication of c-Si PV is nontrivial and lacks electronic tunability. Furthermore, the record efficiency for c-Si PV is 26.7% [5] which is very close to the theoretical limit of 29.4%. [7] This clearly indicates that c-Si PV is a mature technology and there is limited room for improvement. [8] Over the past two decades, third-generation solar cells such as dye-sensitized solar cells, [9,10] quantum dot solar cells, [11,12] organic solar cells, [13,14] and perovskite solar cells (PSCs) [15,16] have been developed as alternatives to c-Si technologies. Of these third-generation solar cells, single-junction PSCs have generated significant attention due to their intense visible to near-infrared absorptivity, [16-18] long diffusion lengths of the charge carriers, [19,20] high efficiency, [21,22] electronic and physical tunability, [23,24] and low manufacturing costs. [25,26] After the first report by Miyasaka's group in 2009, [27] the PCE for single junction devices increased considerably from 3.8% to 25.2%, [27,28] making it the fastest advancing PV technology to date. This has uniquely placed PSCs as the frontrunner technology to potentially replace or coexist with c-Si PV. The term "perovskite" refers to a group of compounds that share the same lattice structure as calcium titanium oxide (CaTiO 3). All PV perovskite materials have the general chemical formula ABX 3 , as illustrated in Figure 1a. Organic-Inorganic hybrid PSCs are typically made using an organic/ inorganic cation (A = methylammonium (MA) CH 3 NH 3 + , formamidinium (FA) CH 3 (NH 2) 2 + , or cesium), a divalent cation (B = Pb 2+ or Sn 2+) , [29] and an anion (X = Cl − , Br − , or I −), illustrated in Figure 1b. [16,30] A is surrounded by eight lead halide octahedra (B in the center of octahedra) and forms a cubic perovskite structure. When the size of A or/and X is changed, the structure of perovskite will distort. The Goldschmidt tolerance factor (t) [31] of perovskite is an empirical index for Organic-inorganic hybrid perovskite solar cells (PSCs) have attracted significant attention in recent years due to their high-power conversion efficiency, simple fabrication, and low material cost. However, due to their high sensitivity to moisture and oxygen, high efficiency PSCs are mainly constructed in an inert environment. This has led to significant concerns associated with the long-term stability and manufacturing costs, which are some of the major limitations for the commercialization of this cutting-edge tech...

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Origin of Open‐Circuit Voltage Enhancements in Planar Perovskite Solar Cells Induced by Addition of Bulky Organic Cations

Cited by 57 publications

References 59 publications

Crown Ether‐Assisted Growth and Scaling Up of FACsPbI₃ Films for Efficient and Stable Perovskite Solar Modules

Crown Ether‐Assisted Growth and Scaling Up of FACsPbI₃ Films for Efficient and Stable Perovskite Solar Modules

Superior Carrier Lifetimes Exceeding 6 µs in Polycrystalline Halide Perovskites

Ambient Fabrication of Organic–Inorganic Hybrid Perovskite Solar Cells

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Origin of Open‐Circuit Voltage Enhancements in Planar Perovskite Solar Cells Induced by Addition of Bulky Organic Cations

Cited by 57 publications

References 59 publications

Crown Ether‐Assisted Growth and Scaling Up of FACsPbI3 Films for Efficient and Stable Perovskite Solar Modules

Crown Ether‐Assisted Growth and Scaling Up of FACsPbI3 Films for Efficient and Stable Perovskite Solar Modules

Superior Carrier Lifetimes Exceeding 6 µs in Polycrystalline Halide Perovskites

Ambient Fabrication of Organic–Inorganic Hybrid Perovskite Solar Cells

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Product

Resources

About

Crown Ether‐Assisted Growth and Scaling Up of FACsPbI₃ Films for Efficient and Stable Perovskite Solar Modules

Crown Ether‐Assisted Growth and Scaling Up of FACsPbI₃ Films for Efficient and Stable Perovskite Solar Modules