Management of the crystallization in two-dimensional perovskite solar cells with enhanced efficiency within a wide temperature range and high stability

Wu, Guo Qing; Zhou, Jianhui; Zhang, Jianqi; Meng, Rui; Wang, Boxin; Xue, Baoda; Leng, Xuanye; Zhang, Dongyang; Zhang, Xuning; Bi, Shiqing; Zhou, Qian; Wei, Zhixiang; Zhou, Huiqiong; Zhang, Yuan

doi:10.1016/j.nanoen.2019.02.002

Cited by 57 publications

(45 citation statements)

References 53 publications

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“…A variety of strategies, including hot‐casting, [ 25,26 ] additive assistance, [ 27,28 ] and solvent engineering, [ 20,21,29 ] have been used to mediate the crystallization of quasi‐2D perovskites, among which hot‐casting has been proven as an effective handle to realize high‐quality quasi‐2D perovskite films with preferred vertical orientation. However, with hot‐casting, it could be difficult to precisely control the phase distribution during film formation, given the rapid crystallization driven by thermal energy and competitions in the growth of 3D and 2D crystals, [ 30 ] originating from fast reactions of PbI 2 to A‐site cations and bulky organic ligands.…”

Section: Figurementioning

confidence: 99%

Water‐Assisted Crystal Growth in Quasi‐2D Perovskites with Enhanced Charge Transport and Photovoltaic Performance

Wang

et al. 2020

Advanced Energy Materials

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Perovskite solar cells (PSCs) employing 3D organic-inorganic hybrid perovskite photoabsorbers have received tremendous progress with state-of-the-art power conversion efficiency (PCE) exceeding 25% during the last a dozen years. [1] However, ambient instability of 3D perovskite materials remains a critical obstacle for realistic applications of PSCs. [2,3] A strategy in addressing the poor stability is to reduce the structural dimensionality of perovskites via the introduction of long-chain organic ligands by forming Ruddlesden-Popper (RP) quasi-2D perovskites. [4,5] The organic ligands are bound to the 3D inorganic framework via coulombic interactions, resulting in a layered structure. The general formula of RP-2D perovskites takes the form of (L) 2 A n−1 Pb n I 3n+1 (n = 1, 2, 3, 4…) where A is the methylammonium (MA +), formamidinium (FA +), or cesium (Cs +) cations, L is the bulky organic ligands, e.g., butylammonium (BA +) or 2-phenylethylammonium (PEA +), and n is the number of layers in the [PbI 6 ] 4− octahedral sheets. [4-7] The incorporation of hydrophobic bulky organic ligands can not only enhance the stability of perovskites with minimized permeation of water molecules but also increase the formation energy of perovskites to mitigate thermal degradation and ion migration. [8-10] These merits alongside the quantum confinement have rendered quasi-2D perovskites great potentials for optoelectronic applications with a wide tunability on the bandgap or photophysical properties. [7] Unfavorably, quasi-2D perovskites are generally associated with a large exciton binding energy (hundreds of meV) due to the insulating nature of bulky organic ligands and the specific layered arrangement. [11,12] As a result, charge transport and extraction are hindered in quasi-2D PSCs. To date, the highest reported PCEs of quasi-2D PSCs (n ≤ 5) remain around 18%, [13-15] showing considerable performance gaps with regard to 3D-PSCs. The PCE (η) of photovoltaic cells is determined by the general relation, J V P FF sc oc light η = × × (V oc is the open-circuit voltage, FF is the fill factor, and P light is the illumination intensity). In quasi-2D PSCs, the relatively low J sc is more restrictive for Organic-inorganic hybrid quasi-2D perovskites have shown excellent stability for perovskite solar cells (PSCs), while the poor charge transport in quasi-2D perovskites significantly undermines their power conversion efficiency (PCE). Here, studies on water-controlled crystal growth of quasi-2D perovskites are presented to achieve high-efficiency solar cells. It is demonstrated that the (BA) 2 MA 4 Pb 5 I 16-based PSCs (n = 5) processed with water-containing precursors display an increased short-circuit current density (J sc) of 19.01 mA cm −2 and PCE over 15%. The enhanced performance is attributed to synergetic growths of the 3D and 2D phase components aided by the formed hydration (MAI•H 2 O), leading to modulations on the crystal orientation and phase distribution of various n-value components, which facilitate interphase charge tr...

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Section: Figurementioning

confidence: 99%

Water‐Assisted Crystal Growth in Quasi‐2D Perovskites with Enhanced Charge Transport and Photovoltaic Performance

Wang

et al. 2020

Advanced Energy Materials

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“…[ 1–3 ] In such materials, lead–iodine slabs are separated by the larger organic cations, forming a structure with general chemical formula of R 2 A n −1 M n X 3 n +1 , where n is the number of lead–iodine layers between organic cation layers R , such as n ‐butylammonium (BA + ) and phenethylammonium (PEA + ). [ 4–6 ] The hydrophobic spacer cations prevent moisture invasion into the perovskite crystal lattice, delivering devices with robust environmental stability. However, the electrical insulation of organic cation layers significantly impacts the crystallinity and charge transfer, resulting in poor device performance.…”

Section: Figurementioning

confidence: 99%

Unraveling the Crystallization Kinetics of 2D Perovskites with Sandwich‐Type Structure for High‐Performance Photovoltaics

et al. 2020

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2D perovskite solar cells with high stability and high efficiency have attracted significant attention. A systematical static and dynamic structure investigation is carried out to show the details of 2D morphology evolution. A dual additive approach is used, where the synergy between an alkali metal cation and a polar solvent leads to high‐quality 2D perovskite films with sandwich‐type structures and vertical phase segregation. Such novel structure can induce high‐quality 2D slab growth and reduce internal and surface defects, resulting in a high device efficiency of 16.48% with enhanced continuous illumination stability and improved moisture (55–60%) and thermal (85 °C) tolerances. Transient absorption spectra reveal the carrier migration from low n to high n species with different kinetics. An [PbI6]4− octagon coalescence transformation mechanism coupled with metal and organic cations wrapped is proposed. By solvent vapor annealing, a recrystallization and reorientation of the 2D perovskite slabs occurs to form an ideal structure with improved device performance and stability.

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“…[ 10 ] Although the improvement in managing the crystal orientation with NP processing has led to impressive developments of efficiency, the device operation of quasi‐2D PSCs is still limited by the detrimental effect of quantum confinement that causes difficulties in charge extraction at low electrical fields ( F ) and resultant decrease of fill factors (FF) that are far below state‐of‐the‐art values in 3D‐PSCs. [ 11–13 ] In general, the unfavorable quantum confinement effect can be gradually diminished through increasing the number of inorganic sheets (or higher n ‐values). [ 14–16 ] Based on a series of quasi‐2D (PEA) 2 (MA) n −1 Pb n I 3 n +1 perovskites ( n = 6, 10, 40, 60, and ∞), Sargent and co‐workers investigated the impact of n ‐value on the photovoltaic behaviors, finding that the best PCE (15.3%) occurred in the device with a large n = 60.…”

Section: Figurementioning

confidence: 99%

Non‐Preheating Processed Quasi‐2D Perovskites for Efficient and Stable Solar Cells

Zhou

et al. 2020

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Although the hot‐casting (HC) technique is prevalent in developing preferred crystal orientation of quasi‐2D perovskite films, the difficulty of accurately controlling the thermal homogeneity of substrate is unfavorable for the reproducibility of device fabrication. Herein, a facile and effective non‐preheating (NP) film‐casting method is proposed to realize highly oriented quasi‐2D perovskite films by replacing the butylammonium (BA+) spacer partially with methylammonium (MA+) cation as (BA)2−x(MA)3+xPb4I13 (x = 0, 0.2, 0.4, and 0.6). At the optimal x‐value of 0.4, the resultant quasi‐2D perovskite film possesses highly orientated crystals, associated with a dense morphology and uniform grain‐size distribution. Consequently, the (BA)1.6(MA)3.4Pb4I13‐based solar cells yield champion efficiencies of 15.44% with NP processing and 16.29% with HC processing, respectively. As expected, the HC‐processed device shows a poor performance reproducibility compared with that of the NP film‐casting method. Moreover, the unsealed device (x = 0.4) displays a better moisture stability with respect to the x = 0 stored in a 65% ± 5% relative humility chamber.

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Management of the crystallization in two-dimensional perovskite solar cells with enhanced efficiency within a wide temperature range and high stability

Cited by 57 publications

References 53 publications

Water‐Assisted Crystal Growth in Quasi‐2D Perovskites with Enhanced Charge Transport and Photovoltaic Performance

Water‐Assisted Crystal Growth in Quasi‐2D Perovskites with Enhanced Charge Transport and Photovoltaic Performance

Unraveling the Crystallization Kinetics of 2D Perovskites with Sandwich‐Type Structure for High‐Performance Photovoltaics

Non‐Preheating Processed Quasi‐2D Perovskites for Efficient and Stable Solar Cells

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