Abstract
Halide perovskites with low-dimensionalities (2D or quasi-2D) have demonstrated outstanding stabilities compared to their 3D counterparts. Nevertheless, poor charge-transporting abilities of organic components in 2D perovskites lead to relatively low power conversion efficiency (PCE) and thus limit their applications in photovoltaics. Here, we report a novel hole-transporting low-dimensional (HT2D) perovskite, which can form a hole-transporting channel on the top surface of 3D perovskite due to self-assembly effects of metal halide frameworks. This HT2D perovskite can significantly reduce interface trap densities and enhance hole-extracting abilities of a heterojunction region between the 3D perovskite and hole-transporting layer. Furthermore, the posttreatment by HT2D can also reduce the crystal defects of perovskite and improve film morphology. As a result, perovskite solar cells (PSCs) can effectively suppress nonradiative recombination, leading to an increasement on photovoltage to >1.20 V and thus achieving >20% power conversion efficiency and >500 h continuous illumination stability. This work provides a pathway to overcome charge-transporting limitations in low-dimensional perovskites and delivers significant enhancements on performance of PSCs.
Highlights
Metal-halide perovskites have been tremendously developed over the past several years because they can offer the promise of easy fabrication, low-cost solution processability, flexible substrate compatibility, broad bandgap tunability, and integration possibility of tandem multijunction architecture [1,2,3,4,5]
TA-PMA was characterized by 1H-NMR (Figure 1(c)), presenting hydrogen signals of the ammonium group (1Ha) at 8.186 (s, 3H) ppm, the benzyl group closer to the ammonium (1Hb) at 7.616 (d, 2H) and 7.496-7.454 (m, 4H) ppm, and the triarylamine group (1Ht) at 7.022 (d, 4H), 6.902 (d, 4H), and 6.792 (d, 2H) ppm, as well as the methylene group a stoichiometric at 4.009 (s, 2H) ppm, respectively, The entire 1H-NMR spectra in of reaction intermediate and the product are shown in Figure S2 and Figure S3
In order to identify the interaction om(1dHfo,bTl2aAHrsh-r)PiafpMttiepodAmot,fao(2n1d:H71.5m,le7t)ah4dsehn(iidofot,debid2sdeHetrov)(,eP3d7b.8.tI49h27)5a,9t(w1s(H,ed2a,mHd2i)iHxsaep)pd,ppmatehna, erdbemdu7,t a.a41tnH0d4at was almost unchanged. These chemical shifts were attributed to varying distances between protonated ammonium and neighboring hydrogens, indicating that the reaction of TA-PMA and PbI2 mainly occurred by the amine group and could potentially achieve a 2D perovskite (n = 1) phases at a molecular level
Summary
Metal-halide perovskites have been tremendously developed over the past several years because they can offer the promise of easy fabrication, low-cost solution processability, flexible substrate compatibility, broad bandgap tunability, and integration possibility of tandem multijunction architecture [1,2,3,4,5]. Owing to the excellent intrinsic properties of perovskite materials, such as extremely high absorption coefficient and ultralong charge carrier diffusion distance, given by the unique three-dimensional (3D) ABX3 framework of perovskite polycrystals [6, 7], perovskite solar cells (PSCs) have achieved very impressive power conversion efficiencies (PCEs) already exceeding 25% [8]. Despite this remarkable achievement, the unacceptable vulnerability of 3D perovskites to humidity and ambient atmosphere rises to a barrier toward their market uptake. 2D and quasi-2D perovskites formed by inserting bulky organic spacer cations, which cannot fit into the octahedral network but can effectively passivate interfacial
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