Interlayer Cross‐Linked 2D Perovskite Solar Cell with Uniform Phase Distribution and Increased Exciton Coupling

Wang, Han; Chan, Christopher C. S.; Chu, Ming; Xie, Jiangsheng; Zhao, Shenghe; Guo, Xinlu; Miao, Qian; Wong, Kam Sing; Yan, Keyou; Xu, Jianbin

doi:10.1002/solr.201900578

Cited by 46 publications

(44 citation statements)

References 39 publications

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“…Furthermore, 2D perovskite with natural QW has a larger exciton binding energy, which may be due to excitons generated in the inorganic layer, and the surrounding organic layer with a low dielectric constant has a strong shielding effect on the excitons. [75,76] Nonetheless, the QW structure has an impressive advantage: adjusting the value of n in 2D perovskite, that is, the width of the "well," can effectively change the bandgap. [77] As shown in Figure 2c,d, for MAPbI 3 and (BA) 2 (MA) n−1 Pb n I 3n+1 (n = 1, 2, 3, 4), when n gradually decrease, the obvious blue shift of the photoluminescence spectrum is observed, with a significant increase in the bandgap (from 1.52 eV (n = ∞) to 2.24 eV (n = 1)).…”

Section: Natural Quantum Well Structurementioning

confidence: 99%

Crystallization Kinetics in 2D Perovskite Solar Cells

Wang

Lei

et al. 2020

Advanced Energy Materials

149

124

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volatile decomposition [23] or halide segregation are often observed in hybrid perovskites under various stress conditions (light, [24] thermal, [25] and electric fields [26]); 4) spontaneous phase transition easily occurs for perovskite with unstable crystal structures, particularly for inorganic perovskite. [27-29] To improve the stability of PSCs, researchers attempted numerous methods such as encapsulation, [30] additive engineering, [31] component engineering, [32] etc. [33] However, the PSCs' stability is yet to achieve a perfect solution. Recently, researchers found that the introduction of long-chain organic cations in 3D perovskite as 2D perovskite can block water and oxygen molecules, meanwhile, generate a steric effect to prevent phase transitions, and limit ion migration. [34-36] Hence, fabricating 2D [37,38] or 2D/3D [39-43] mixed perovskite as absorbing layers are effective approaches to improve the stability of PSCs. However, the PCE of 2D PSCs remain lower than that of the 3D ones, which is mainly attributed to the introduction of organic macromolecules that blocks the effective extraction and transport of carriers. [44,45] Fortunately, 2D perovskite usually has three arrangements, namely parallel, perpendicular to the glass substrate or randomly arranged. [46] Manipulating the orientation of the crystal and the phase distribution in the 2D solution-processed perovskite can improve the efficiency and reproducibility of the device. Among them, the most desired arrangement for PSCs is the one that perpendicular to the substrate. Therefore, studying the crystallization kinetics of 2D perovskite is curial to effectively control the film forming process and adjust the crystal orientation (perpendicular to the substrate), which can effectively avoid or reduce the adverse effects of the organic molecular layer and improve device efficiency. [47,48] Nevertheless, few review articles were published on this subject. In this review, we mainly focus on the key issue for controlling crystallization kinetics and summarizing the research progress of their effects on various types of 2D PSCs. We also discuss the crystal/natural quantum well (QW) structure and the original stability for 2D PSCs in detail. Finally, remaining challenges and outlooks are presented. 2. Crystal and Natural Quantum Well Structure The material structure has a substantial impact on performance. [49-51] Properties of 2D and 3D perovskites differ 2D perovskites demonstrate higher moisture stability, oxygen content, thermal stability, and a significantly lower ion migration/phase transition occurrence in comparison to 3D perovskite. These advantages imply huge potential for 2D perovskite in commercial applications in the photovoltaic field. However, the horizontal arrangement of the organic layer severely hinders the transport of carriers, and thus, the power conversion efficiency of 2D perovskite solar cells (PSCs) is significantly lower than that of 3D. Controlling the crystallization orientation to achieve rapid carrier transport can effe...

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Section: Natural Quantum Well Structurementioning

confidence: 99%

Crystallization Kinetics in 2D Perovskite Solar Cells

Wang

Lei

et al. 2020

Advanced Energy Materials

149

124

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“…[13,24] The reduced E b of BDAPbI 4 PSC indicates that the quantum confinement effect is weakened, which might be caused by the interlayer exciton coupling. [25] Also, the PL spectrum shows a sharp and narrow peak at 502 nm with a full-width at half-maximum (FWHM) of 18 nm ( Figure S3, Supporting Information), indicating a low trap density in the BDAPbI 4 PSC. In addition, the trap state density of the BDAPbI 4 PSC was measured using the space-chargelimited current (SCLC) method.…”

Section: (3 Of 9)mentioning

confidence: 99%

2D Perovskite Single Crystals with Suppressed Ion Migration for High‐Performance Planar‐Type Photodetectors

Zhang

Liu

et al. 2020

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Abstract2D Dion–Jacobson (DJ) perovskites have recently drawn much attention owing to their superior charge transport and high environmental stability. Unfortunately, their intrinsic optoelectronic properties are largely unexplored due to the lack of high‐quality single crystals available for accurate measurements. Herein, a reactive, low‐temperature‐gradient crystallization process to grow high‐quality 2D perovskite single crystal (BDAPbI4) using symmetric straight chain 1,4‐butanediammonium as a short‐chain insulating spacer is developed. It is found that the BDAPbI4 single crystal exhibits a direct bandgap with effective charge collection (μτ = 1.45 × 10−3 cm2 V−1). In particular, the BDAPbI4 single crystal shows a high ion migration activation energy (0.88 eV) that is desired for stability. Moreover, the planar‐type photodetectors made of BDAPbI4 single crystals demonstrate excellent photoresponse performance, including large dynamic linear range (150 dB), high responsivity (927 mA W−1), fast response speed, and exceptional stability. Theoretical calculations reveal that the enhanced carrier transport properties are mainly attributed to the interlayer‐induced coupling of the inorganic layers. Furthermore, the rigid structure of BDAPbI4, resulting from the strong hydrogen bonds between the organic cations and the inorganic framework, will result in both low defect density and low ion migration, leading to superior carrier transport properties and detection performance.

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“…This disadvantage could be circumvented by making crystals with out‐of‐plane (OP) orientation, [ 15 ] reduced defect density, and tailored organic cations. [ 30–33 ] Therefore, methods to achieve crystal with preferred OP orientation and high crystallinity are highly desired. In addition, controlling the distribution of layer number ( n ) to avoid the formation of high n ‐value phase (e.g., n > 10) is critical for the long‐term stability of quasi‐2D perovskites.…”

Section: Introductionmentioning

confidence: 99%

Suppressing the Excessive Solvated Phase for Dion–Jacobson Perovskites with Improved Crystallinity and Vertical Orientation

et al. 2020

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Dion–Jacobson (DJ)‐type quasi‐two‐dimensional perovskites exhibit improved stabilities than their 3D counterparts but meanwhile limited charge transport properties. Knowledge to manipulate the crystal orientation and crystallinity is the primary issue for DJ perovskite with high power conversion efficiencies (PCEs). Herein, the nucleation of DJ perovskite films is divided into three stages and the formation of PbI2–N,N‐dimethylformamide (DMF)‐based solvated phase (PDS) is highlighted as the initial stage. For the first time, it is demonstrated that regulating the amount of PDS precipitation in stage I by MACl additive is the key to ensure the downward growth of DJ perovskites with out‐of‐plane orientation and high crystallinity in stage III, which is valid for DJ perovskites with different bukly organic cations including p‐phenylenediamine (PPD), p‐xylylenediamine (PXD), and propane‐1,3‐diammonium (PDA). For (PXD)(MA)2Pb3I10‐based perovskite solar cells, the PDS engineering lead to a dramtically improved PCE from 1.2% to 15.6%. Moreover, based on temperature‐dependent ionic conductivity measurement, it is confirmed that the ion migration in DJ perovskite films is efficiently suppressed, despite the possible coexisting 3D perovskite phase. The unencapsulated PXD‐based DJ perovskite devices retain over 90% efficiencies after 700 h of continuous illumination or 1500 h of storage in glove box.

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Interlayer Cross‐Linked 2D Perovskite Solar Cell with Uniform Phase Distribution and Increased Exciton Coupling

Cited by 46 publications

References 39 publications

Crystallization Kinetics in 2D Perovskite Solar Cells

Crystallization Kinetics in 2D Perovskite Solar Cells

2D Perovskite Single Crystals with Suppressed Ion Migration for High‐Performance Planar‐Type Photodetectors

Suppressing the Excessive Solvated Phase for Dion–Jacobson Perovskites with Improved Crystallinity and Vertical Orientation

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