Plasma-Exposure-Induced Mobility Enhancement of LiTFSI-Doped Spiro-OMeTAD Hole Transport Layer in Perovskite Solar Cells and Its Impact on Device Performance

2,2′,7,7′-Tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene (spiro-OMeTAD) film currently prevails as hole transport layer (HTL) employed in perovskite solar cells (PSCs). However, the standard preparation method for spin-coated, Lithium bis(trifluoromethylsulfony) imide (LiTFSI)-doped, spiro-OMeTAD HTL depends on a time-consuming and uncontrolled oxidation process to gain desirable electrical conductivity to favor device operation. Our previous work demonstrated that ~10 s oxygen or oxygen containing gas discharge plasma exposure can oxidize spiro-OMeTAD HTL effectively and make PSCs work well. In this communication, hole-only devices are fabricated and in-situ current density-voltage measurements are performed to investigate the change in hole mobility of LiTFSI-doped spiro-OMeTAD films under plasma exposure. The results reveal that hole mobility values can be increased averagely from ~5.0 × 10−5 cm2V−1s−1 to 7.89 × 10−4 cm2V−1s−1 with 7 s O2 plasma exposure, and 9.33 × 10−4 cm2V−1s−1 with 9 s O2/Ar plasma exposure. The effects on the photovoltaic performance of complete PSC devices are examined, and optical emission spectroscopy (OES) is used for a diagnostic to explain the different exposure effects of O2 and O2/Ar plasma. High efficiency, fine controllability and good compatibility with current plasma surface cleaning techniques may make this method an important step towards the future commercialization of photovoltaic technologies employing spiro-OMeTAD hole transport material.

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CuI/Spiro-OMeTAD Double-Layer Hole Transport Layer to Improve Photovoltaic Performance of Perovskite Solar Cells

Coatings ◽

10.3390/coatings11080978 ◽

2021 ◽

Vol 11 (8) ◽

pp. 978

Author(s):

Chaoqun Lu ◽

Weijia Zhang ◽

Zhaoyi Jiang ◽

Yulong Zhang ◽

Cong Ni

Keyword(s):

Solar Cells ◽

Double Layer ◽

Photovoltaic Performance ◽

Perovskite Solar Cells ◽

Hole Transport ◽

Transport Layer ◽

Hole Transport Layer ◽

Photoelectric Conversion Efficiency ◽

Photoelectric Conversion ◽

Perovskite Layer

The hole transport layer (HTL) is one of the main factors affecting the efficiency and stability of perovskite solar cells (PSCs). However, obtaining HTLs with the desired properties through current preparation techniques remains a challenge. In the present study, we propose a new method which can be used to achieve a double-layer HTL, by inserting a CuI layer between the perovskite layer and Spiro-OMeTAD layer via a solution spin coating process. The CuI layer deposited on the surface of the perovskite film directly covers the rough perovskite surface, covering the surface defects of the perovskite, while a layer of CuI film avoids the defects caused by Spiro-OMetad pinholes. The double-layer HTLs improve roughness and reduce charge recombination of the Spiro-OMeTAD layer, thereby resulting in superior hole extraction capabilities and faster hole mobility. The CuI/Spiro-OMeTAD double-layer HTLs-based devices were prepared in N2 gloveboxes and obtained an optimized PCE (photoelectric conversion efficiency) of 17.44%. Furthermore, their stability was improved due to the barrier effect of the inorganic CuI layer on the entry of air and moisture into the perovskite layer. The results demonstrate that another deposited CuI film is a promising method for realizing high-performance and air-stable PSCs.

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The Performance Improvement of Using Hole Transport Layer with Lithium and Cobalt for Inverted Planar Perovskite Solar Cell

Coatings ◽

10.3390/coatings10040354 ◽

2020 ◽

Vol 10 (4) ◽

pp. 354

Author(s):

Shaoxi Wang ◽

He Guan ◽

Yue Yin ◽

Chunfu Zhang

Keyword(s):

Solar Cells ◽

Short Circuit ◽

Perovskite Solar Cells ◽

Hole Mobility ◽

Short Circuit Current ◽

Short Circuit Current Density ◽

Hole Transport ◽

Transport Layer ◽

Hole Transport Layer ◽

Planar Heterojunction

With the continuous development of solar cells, the perovskite solar cells (PSCs), whose hole transport layer plays a vital part in collection of photogenerated carriers, have been studied by many researchers. Interface transport layers are important for efficiency and stability enhancement. In this paper, we demonstrated that lithium (Li) and cobalt (Co) codoped in the novel inorganic hole transport layer named NiOx, which were deposited onto ITO substrates via solution methods at room temperature, can greatly enhance performance based on inverted structures of planar heterojunction PSCs. Compared to the pristine NiOx films, doping a certain amount of Li and Co can increase optical transparency, work function, electrical conductivity and hole mobility of NiOx film. Furthermore, experimental results certified that coating CH3NH3PbIxCl3−x perovskite films on Li and Co- NiOx electrode interlayer film can improve chemical stability and absorbing ability of sunlight than the pristine NiOx. Consequently, the power conversion efficiency (PCE) of PSCs has a great improvement from 14.1% to 18.7% when codoped with 10% Li and 5% Co in NiOx. Moreover, the short-circuit current density (Jsc) was increased from 20.09 mA/cm2 to 21.7 mA/cm2 and the fill factor (FF) was enhanced from 0.70 to 0.75 for the PSCs. The experiment results demonstrated that the Li and Co codoped NiOx can be a effective dopant to improve the performance of the PSCs.

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Surface treatment via Li-bis-(trifluoromethanesulfonyl) imide to eliminate the hysteresis and enhance the efficiency of inverted perovskite solar cells

Journal of Materials Chemistry C ◽

10.1039/c7tc03984k ◽

2017 ◽

Vol 5 (39) ◽

pp. 10280-10287 ◽

Cited By ~ 6

Author(s):

Cong Chen ◽

Guang Yang ◽

Junjie Ma ◽

Xiaolu Zheng ◽

Zhiliang Chen ◽

...

Keyword(s):

Solar Cells ◽

Surface Treatment ◽

Power Conversion ◽

Photovoltaic Performance ◽

Perovskite Solar Cells ◽

Hole Transport ◽

Transport Layer ◽

Hole Transport Layer ◽

Long Term Stability

We showed that perovskite solar cells employing Li-treated NiOxas a hole transport layer demonstrated excellent photovoltaic performance, and obtained a power conversion efficiency of up to 18.03%. In addition, the device possessed good long-term stability.

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Perovskite solar cells with a DMSO-treated PEDOT:PSS hole transport layer exhibit higher photovoltaic performance and enhanced durability

Nanoscale ◽

10.1039/c6nr08375g ◽

2017 ◽

Vol 9 (12) ◽

pp. 4236-4243 ◽

Cited By ~ 81

Author(s):

Di Huang ◽

Tenghooi Goh ◽

Jaemin Kong ◽

Yifan Zheng ◽

Suling Zhao ◽

...

Keyword(s):

Solar Cells ◽

Photovoltaic Performance ◽

Perovskite Solar Cells ◽

Hole Transport ◽

Transport Layer ◽

Hole Transport Layer

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The Way to Pursue Truly High-Performance Perovskite Solar Cells

Nanomaterials ◽

10.3390/nano9091269 ◽

2019 ◽

Vol 9 (9) ◽

pp. 1269 ◽

Cited By ~ 3

Author(s):

Wu ◽

Thakur ◽

Chiang ◽

Chandel ◽

Wang ◽

...

Keyword(s):

Solar Cells ◽

Photovoltaic Performance ◽

Perovskite Solar Cells ◽

Hole Transport ◽

Transport Layer ◽

Hot Electrons ◽

Electron Transport Layer ◽

Hole Transport Layer ◽

Hot Carriers ◽

Potential Loss

The power conversion efficiency (PCE) of single-junction solar cells was theoretically predicted to be limited by the Shockley–Queisser limit due to the intrinsic potential loss of the photo-excited electrons in the light absorbing materials. Up to now, the optimized GaAs solar cell has the highest PCE of 29.1%, which is close to the theoretical limit of ~33%. To pursue the perfect photovoltaic performance, it is necessary to extend the lifetimes of the photo-excited carriers (hot electrons and hot holes) and to collect the hot carriers without potential loss. Thanks to the long-lived hot carriers in perovskite crystal materials, it is possible to completely convert the photon energy to electrical power when the hot electrons and hot holes can freely transport in the quantized energy levels of the electron transport layer and hole transport layer, respectively. In order to achieve the ideal PCE, the interactions between photo-excited carriers and phonons in perovskite solar cells has to be completely understood.

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Efficient inverted planar perovskite solar cells based on inorganic hole-transport layers from nickel-containing organic sol

Functional Materials Letters ◽

10.1142/s1793604718500881 ◽

2019 ◽

Vol 12 (01) ◽

pp. 1850088 ◽

Cited By ~ 2

Author(s):

Weina Zhang ◽

Jie Tang ◽

Jihuai Wu ◽

Zhang Lan

Keyword(s):

Solar Cells ◽

Photovoltaic Performance ◽

Perovskite Solar Cells ◽

Hole Transport ◽

Transport Layer ◽

Simple Solution ◽

Hole Transport Layer ◽

Solution Processed ◽

Transport Dynamics ◽

Nio Nanocrystals

Due to the rough surface of fluorine-doped tin oxide (FTO) conductive glasses, it is challenging to fabricate fully covered ultra-thin hole-transport layer (HTL) with thickness under 100[Formula: see text]nm by a simple solution-processed method. Yet, the quality of HTLs play a key role in determining photovoltaic performance of the inverted planar perovskite solar cells (PSCs) owing to their important functions for effectively extracting holes, blocking electrons, suppressing dark reaction, and so on. Here, we report a facile nickel-containing organic sol (Ni–Sol) route to fabricate fully covered 46[Formula: see text]nm thick NiO HTLs for efficient inverted planar PSCs. Comparing with the pre-synthesized NiO nanocrystals solution, the Ni–Sol is easier to spread around the rough outline of FTO to achieve higher surface coverage. Through optimizing the concentration of nickel-containing organic sol, the champion performance of the inverted planar PSCs can be achieved because of the high transparency and good hole-transport dynamics of the optimized NiO film. This work demonstrates the advanced Ni–Sol route for preparing efficient inverted planar PSCs by the simple solution-processed method.

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Efficient perovskite solar cells with negligible hysteresis achieved by sol–gel-driven spinel nickel cobalt oxide thin films as the hole transport layer

Journal of Materials Chemistry C ◽

10.1039/c9tc00902g ◽

2019 ◽

Vol 7 (24) ◽

pp. 7288-7298 ◽

Cited By ~ 7

Author(s):

Ju Ho Lee ◽

Young Wook Noh ◽

In Su Jin ◽

Sang Hyun Park ◽

Jae Woong Jung

Keyword(s):

Solar Cells ◽

High Efficiency ◽

Sol Gel ◽

Photovoltaic Performance ◽

Perovskite Solar Cells ◽

Critical Issue ◽

Hole Transport ◽

Transport Layer ◽

Hole Transport Layer ◽

Current Voltage

Current–voltage hysteresis is a critical issue that impacts the photovoltaic performance of perovskite solar cells, and thus, it is imperative to develop high-efficiency perovskite solar cells without hysteresis behavior.

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High-Hole-Mobility Metal–Organic Framework as Dopant-Free Hole Transport Layer for Perovskite Solar Cells

Nanoscale Research Letters ◽

10.1186/s11671-021-03643-7 ◽

2022 ◽

Vol 17 (1) ◽

Author(s):

Ruonan Wang ◽

Weikang Yu ◽

Cheng Sun ◽

Kashi Chiranjeevulu ◽

Shuguang Deng ◽

...

Keyword(s):

Solar Cells ◽

Metal Organic Framework ◽

Perovskite Solar Cells ◽

Hole Mobility ◽

Hole Transport ◽

Transport Layer ◽

Hole Transport Layer ◽

Free Hole ◽

Metal Organic ◽

Organic Framework

AbstractA dopant-free hole transport layer with high mobility and a low-temperature process is desired for optoelectronic devices. Here, we study a metal–organic framework material with high hole mobility and strong hole extraction capability as an ideal hole transport layer for perovskite solar cells. By utilizing lifting-up method, the thickness controllable floating film of Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 at the gas–liquid interface is transferred onto ITO-coated glass substrate. The Ni3(2,3,6,7,10,11-hexaiminotriphenylene)2 film demonstrates high compactness and uniformity. The root-mean-square roughness of the film is 5.5 nm. The ultraviolet photoelectron spectroscopy and the steady-state photoluminescence spectra exhibit the Ni3(HITP)2 film can effectively transfer holes from perovskite film to anode. The perovskite solar cells based on Ni3(HITP)2 as a dopant-free hole transport layer achieve a champion power conversion efficiency of 10.3%. This work broadens the application of metal–organic frameworks in the field of perovskite solar cells. Graphical Abstract

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