Dopant-Free Hole-Transporting Polymers for Efficient and Stable Perovskite Solar Cells

Valero, Silvia; Collavini, Silvia; Völker, Sebastian F.; Saliba, Michael; Tress, Wolfgang; Zakeeruddin, Shaik M.; Grätzel, Michaël; Delgado, Juan Luis

doi:10.1021/acs.macromol.9b00165

Cited by 53 publications

(37 citation statements)

References 40 publications

(57 reference statements)

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“…Data in Table confirm this trend since P2 cells have lower R S and higher R SH (nearly one order of magnitude) than the P1 ‐based cells. As observed in earlier reports, a low FF is an indicator of low mobility and conductivity of the material . The intermolecular charge transport is enhanced upon thionation, as demonstrated in Section , thus explaining the increase in the FF of the corresponding DTPP‐based photovoltaic devices.…”

Section: Resultssupporting

confidence: 70%

Thionation Enhances the Performance of Polymeric Dopant‐Free Hole‐Transporting Materials for Perovskite Solar Cells

Zhang

Liu

Yang

et al. 2019

Adv Materials Inter

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To date, the most efficient perovskite solar cells (PSCs) require hole‐transporting materials (HTMs) that are doped with hygroscopic additives to improve their performance. Unfortunately, such dopants negatively impact the overall PSCs stability and add cost and complexity to the device fabrication. Hence, there is a need to investigate new strategies to boost the typically modest performance of dopant‐free HTMs for efficient and stable PSCs. Thionation is a simple and single‐step approach to enhance the carrier‐transport capability of organic semiconductors, yet still completely unexplored in the context of HTMs for PSCs. In this work, a novel polymeric semiconductor, P1, based on a diketopyrrolopyrrole (DPP) moiety, is proposed as a dopant‐free HTM. Its modest performance in PSCs (power conversion efficiency (PCE) = 7.1%) is significantly enhanced upon thionation of the DPP moiety. The resulting dithioketopyrrolopyrrole‐based HTM, P2, leads to PSCs with nearly 40% performance improvement (PCE = 9.7%) compared to devices based on the nonthionated HTM (P1). Furthermore, thionation also remarkably boosts the shelf‐storage and thermal stability with respect to traditional 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene‐based PSCs. This work provides useful insights to further design effective dopant‐free HTMs employing the straightforward one‐step thionation strategy for efficient and stable PSCs.

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Section: Resultssupporting

confidence: 70%

Thionation Enhances the Performance of Polymeric Dopant‐Free Hole‐Transporting Materials for Perovskite Solar Cells

Zhang

Liu

Yang

et al. 2019

Adv Materials Inter

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“…It might be attributed to hydrophilic TEG groups in the alkoxy‐PTEG. However, when considering the high humidity condition and other recent dopant‐free HTMs, the stability data seem very good . The encapsulated alkoxy‐PTEG device was also tested at the same ambient conditions (Figure S15, Supporting Information).…”

Section: Resultsmentioning

confidence: 95%

Nonaromatic Green‐Solvent‐Processable, Dopant‐Free, and Lead‐Capturable Hole Transport Polymers in Perovskite Solar Cells with High Efficiency

Lee

Kim

et al. 2020

Advanced Energy Materials

152

117

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With the recent developments in the efficiency of perovskite solar cells (PSCs), diverse functionalities are necessary for next‐generation charge‐transport layers. Specifically, the hole‐transport layer (HTL) in the various synthesized materials modified with functional groups is explored. A novel donor–acceptor type polymer, alkoxy‐PTEG, composed of benzo[1,2‐b:4,5:b′]dithiophene and tetraethylene glycol (TEG)‐substituted 2,1,3‐benzothiadiazole is reported. The alkoxy‐PTEG exhibits high solubility even in nonaromatic solvents, such as 3‐methylcyclohexanone (3‐MC), and can prevent possible lead leakage via chelation. The optical and electronic properties of alkoxy‐PTEG are thoroughly analyzed. Finally, a dopant‐free alkoxy‐PTEG device processed with 3‐MC exhibits 19.9% efficiency and a device with 2‐methyl anisole, which is a reported aromatic food additive, exhibits 21.2% efficiency in a tin oxide planar structure. The PSC device shows 88% stability after 30 d at ambient conditions (40–50% relative humidity and room temperature). In addition, nuclear magnetic resonance reveals that TEG groups can chelate lead ions with moderate strength (Kbinding = 2.76), and this strength is considered to be nondestructive to the perovskite lattice to prevent lead leakage. This is the first report to consider lead leakage and provide solutions to reduce this problem.

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“…However, the introduction of dopants or additives not only complicates the device preparation process and increases the fabrication costs, but also leads to an enlarged stability problem. For example, it has been reported that the Li‐TFSI dopant and 4‐ tert ‐butylpyrifine (TBP) additive can lead to the formation of high density of pinholes in the spiro‐OMeTAD layer and the redistribution of the Li‐TFSI dopant . In addition, the Li‐TFSI dopant and TBP additive have been reported to accelerate the degradation of PSCs due to their hygroscopic properties …”

Section: Recent Important Progresses On Interfacial Materialsmentioning

confidence: 99%

Review on Practical Interface Engineering of Perovskite Solar Cells: From Efficiency to Stability

et al. 2019

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Exceptionally high efficiencies for organic–inorganic hybrid perovskite solar cells (PSCs) have been achieved. However, their operational stability still needs to be improved. The intrinsic instability of halide perovskites caused by the presence of volatile organic cations, as well as the degradation of hybrid perovskites induced by the adverse permeation of environmental water (H2O)/oxygen (O2) and the undesired ion diffusion or migration are the major reasons. Beyond strengthening perovskites themselves, interface engineering is now regarded as a valid strategy to prolong device lifetime by preventing the undesired degradation pathways. This comprehensive review highlights the utilization of practical interface engineering for enhancing the efficiency and stability of organic–inorganic lead halide PSCs. First, the impacts of interface design on the energy‐level alignment and carrier dynamics are overviewed. Second, recent progresses on the development of interfacial materials for simultaneously achieving high efficiency and stability of PSCs are summarized. At last, the interfacial layer design principles along with future outlook of this rapidly developing field are discussed.

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Dopant-Free Hole-Transporting Polymers for Efficient and Stable Perovskite Solar Cells

Cited by 53 publications

References 40 publications

Thionation Enhances the Performance of Polymeric Dopant‐Free Hole‐Transporting Materials for Perovskite Solar Cells

Thionation Enhances the Performance of Polymeric Dopant‐Free Hole‐Transporting Materials for Perovskite Solar Cells

Nonaromatic Green‐Solvent‐Processable, Dopant‐Free, and Lead‐Capturable Hole Transport Polymers in Perovskite Solar Cells with High Efficiency

Review on Practical Interface Engineering of Perovskite Solar Cells: From Efficiency to Stability

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