Organic Hole Transport Layer Research Articles

Simulation of Triple-Cation Perovskite Solar Cells: Key Design Factors for Efficiency Promotion

Compositional engineering is considered one of the recent interesting techniques used in the field of perovskite solar cells (PSCs). In this method, more than one material was used in a specific cation in the perovskite structure. This work aims to simulate the cesium-containing triple-cation perovskite (TCP) via the SCAPS-1D simulation program with a device structure of ITO/SnO2/TCP/Spiro-OMeTAD/Au. First, we studied the effect of interface defects on the PCSs with respect to experimental results and found that when no interface defects occur, the power conversion efficiency (PCE) reaches a value of 22.16% which is higher than the reported PCE, implying that the fabricated cell suffers from the interface defects as a main effect on cell degradation. Incorporating interface defects into the simulation results in a very good match between the experimental and simulated data with a PCE of 17.92%. Further, to provide possible routes to enhance the performance of the solar cell under investigation, impacts of absorber layer thickness, conduction band offset (CBO), surface recombination velocity, and light intensity were explored. In addition, hole transport layer (HTL)-free design was investigated to alleviate the instability issues associated to the organic HTL, leading to a PCE of 18.28%, for a surface velocity of 104 cm/s, which is interestingly higher than the initial cell. The provided study reveals the critical role of interface defects and other key design factors and suggests potential solutions to alleviate the subsequent degradation mechanisms, thereby enhancing the overall cell performance.

Structurally Driven Ultrafast Charge Funneling in Organic Bulk Heterojunction Hole Transport Layer for Efficient Colloidal Quantum Dot Photovoltaics

AbstractNanoscopic packing structures crucially determine the charge conduction and the consequent functionalities of organic semiconductors including bulk heterojunctions (BHJs), which are dependent on various processing parameters. Today's high‐performance colloidal quantum dot photovoltaics (CQDPVs) employ functional organic semiconductors as a hole transport layer (HTL). However, the processing of those films replicates a protocol dedicated to high‐performance organic PVs, and thus little is known about how to control the molecular packing structures to maximize the hole extraction function of the HTLs. Herein, it is uncovered that the random‐oriented, but closer‐packed BHJ crystallites, constructed by 1,2‐dichlorobenzene (o‐DCB) as a solvent, allow exceptional charge conduction vertically across the film and restrict diffusion‐driven charge transfer process, enabling ultrafast hole funneling from CQD to BHJ to be extracted. As a result, a power conversion efficiency of 13.66% with high photocurrent >34 mA cm−2 is achieved by employing o‐DCB‐processed BHJ HTL, far exceeding the performance of the CQDPV solely employing neat polymer HTL. A charge conduction mechanism associated with the BHJ HTL structure suppressing the bimolecular recombination is proposed. This works not only suggests key principles to control the packing structures of organic HTLs but also opens a new avenue to boost optoelectronic performance.

Stable Methylammonium‐Free p‐i‐n Perovskite Solar Cells and Mini‐Modules with Phenothiazine Dimers as Hole‐Transporting Materials

During the last decade, perovskite solar technologies underwent an impressive development, with power conversion efficiencies reaching 25.5% for single‐junction devices and 29.8% for Silicon‐Perovskite tandem configurations. Even though research mainly focused on improving the efficiency of perovskite photovoltaics (PV), stability and scalability remain fundamental aspects of a mature photovoltaics technology. For n‐i‐p structure perovskite solar cells, using poly‐triaryl(amine) (PTAA) as hole transport layer (HTL) allowed to achieve marked improvements in device stability compared with other common hole conductors. For p‐i‐n structure, poly‐triaryl(amine) is also routinely used as dopant‐free hole transport layer, but problems in perovskite film growth, and its limited resistance to stress and imperfect batch‐to‐batch reproducibility, hamper its use for device upscaling. Following previous computational investigations, in this work, we report the synthesis of two small‐molecule organic hole transport layers (BPT‐1,2), aiming to solve the above‐mentioned issues and allow upscale to the module level. By using BPT‐1 and methylammonium‐free perovskite, max. Power conversion efficiencies of 17.26% and 15.42% on a small area (0.09 cm2) and mini‐module size (2.25 cm2), respectively, were obtained, with a better reproducibility than with poly‐triaryl(amine). Moreover, BPT‐1 was demonstrated to yield more stable devices compared with poly‐triaryl(amine) under ISOS‐D1, T1, and L1 accelerated life‐test protocols, reaching maximum T90 values >1000 h on all tests.

Versatile Use of 1,12-Diaminododecane as an Efficient Charge Balancer for High-Performance Quantum-Dot Light-Emitting Diodes

Balancing the charge injection rates in the emissive layer (EML) is a key factor in achieving high-performance quantum-dot light-emitting diodes (QD-LEDs). This has mostly been pursued by controlling the injection rate of one type of charge carrier (typically electrons). Simultaneous engineering of both types of charge carriers, however, would be more efficient in achieving the desired charge balance within a device. Herein, the versatile use of 1,12-diaminododecane (DAD) ligands is proposed to achieve balanced charge injection rates into the QD EML, thereby enhancing QD-LED performance. By utilizing the dipole moment and short chain lengths, DAD ligands function as efficient electron retarders and hole boosters. Specifically, DAD treatment on the surface of zinc oxide generates an electronic barrier to QDs. Meanwhile, DAD treatment on the surface of the QDs reduces the potential difference between the organic hole transport layers and QDs. Consequently, the QD-LEDs with the adoption of DAD at the two different positions exhibit balanced charge injection rates into the QDs, enhancing device efficiency and operational stability. The present study proposes a simple yet efficient chemical method that controls both electron and hole injection properties to achieve high-performance QD-LEDs.

Anion‐Modulated Chemical Doping of Organic Hole Conductor Boosts Efficiency and Stability of Perovskite Solar Cells

AbstractChemical doping of organic semiconductors enables significant progress in improving their optoelectronic performance. However, the correlation between doping counter ions and charge‐transport mechanism has not been yet well‐understood. In this study, it is discovered that the anion‐dependent degree of delocalization (DOD) of lithium‐based dopants significantly determines the doping kinetics as well as the conductivity of organic hole transport layer (HTL), leading to large variation in solar cell efficiency and device stability. Specifically, the incorporation of bis(pentafluoroethanesulfonyl) imide (PFSI−) as the anion with a high DOD results in one order of magnitude higher film conductivity and thus an elevated power conversion efficiency (PCE) exceeding 22.1%, much higher than the state‐of‐the‐art lithium bis(trifluoromethane)sulfonimide (LiTFSI) (21.1%) and lithium hexafluorophosphate (LiPF6) (20.0%). Moreover, the dopant LiPF6 with a smaller DOD produces higher doping yield of HTL accompanied by stronger light‐induced PCE fluctuation. Structural analysis reveals anion‐modulated ion exchange kinetics determine the hole‐transport mechanism and device photostability. To mitigate these detrimental effects, a versatile strategy of Li+ solvation is developed to modulate the anion dissociation, enabling simultaneous improvement of device efficiency and stability. This study elucidates an intriguing and generally applicable doping mechanism, and envisages a bright future to further developing efficient and stable organic electronics.

Prospective efficiency boosting of full-inorganic single-junction Sb2(S, Se)3 solar cell

Antimony selenosulfide, Sb 2 (S, Se) 3 , is regarded as an appropriate absorber to be utilized in terrestrial single junction solar cell applications thanks to the tunability of its bandgap energy which could be adjusted around 1.3 eV. To enhance the power conversion efficiency (PCE) of Sb 2 (S, Se) 3 -based single junction solar cell, we propose some design recommendations by using device simulation. First, in order to validate the simulation model, a calibration step is accomplished by comparing the numerical simulation results with those of a fabricated cell structure consisting of Au/Sb 2 (S, Se) 3 /CdS/ITO. The designed cell is formed without an organic hole transport layer (HTL) which, generally, harmfully affects the cell by causing stability issues. Next, we investigate the impact of the conduction band offset (CBO) between the electron transport layer (ETL) and the Sb 2 (S, Se) 3 absorber utilizing the bandgap tunable material Cd 1-x Zn x S to achieve the optimum CBO. Various key design parameters for the presented cell such as the back contact work function as well as absorber thickness and doping concentration are also inspected. It is found that the most crucial parameter that affects the cell performance is the CBO which could be adjusted by modifying the Zn fraction in the ternary compound Cd 1-x Zn x S. Moreover, a study on the impact of the interface and bulk defects on device performance is carried out. The simulations, conducted in this study, are accomplished by SCAPS-1D simulator at 300 K temperature and under AM1.5G illumination. • Device simulation of full-inorganic Sb 2 (S, Se) 3 solar cell (SC) was comprehensively performed. • An energy band offset engineering was applied to maximize the efficiency. • The impact of different parameters on the device performance was fully discussed. • An efficiency up to 14.86% could be obtained for the optimized cell. • The work promotes future performance enhancement for Sb 2 (S, Se) 3 -based single-junction SC.

Interface engineering of organic hole transport layer with facile molecular doping for highly efficient perovskite solar cells

Energy level and the charge extraction/transportation ability of the hole transport layer (HTL) have significant impacts on the photovoltaic (PV) parameters of the perovskite solar cell (PSC) devices. A doping process has been one of the representative works to manage these characteristics, but the solution-blend doping, widely applied to the organic semiconductor HTL, has shown limited processability. In this work, we design a facile interfacial doping process for poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) HTL in p-i-n structure PSC device. This approach provides superior optical and electrical properties to the PTAA layer, even with better processability, and its proper hydrophobicity is beneficial to forming pinhole-free perovskite even with superior crystallinity and reduced trap density. Moreover, the dipole layer localized at the interface with the perovskite enhance the built-in potential of device, improving its carrier transportation. As a result, this approach largely enhances the efficiency of the p-i-n PSC device from 18.06% (blend-doping) to 20.67% with superior stability preserving 94% of its initial efficiency after 500 h under ambient air.

Recent Advances in Organic and Inorganic Hole and Electron Transport Layers for Organic Solar Cells: Basic Concept and Device Performance

The emergence of nonfullerene small-molecule acceptors (NFSMA) with the advantages of synthetic versatility, high absorption coefficient in wide wavelength range, and high thermal stability has attained the power conversion efficiency (PCE) exceeding 19% for resulted organic solar cells (OSCs) with the optimization of interface engineering and active layer morphology. Interfacial layers including both hole transporting layer (HTL) and electron transporting layer (ETL) are equally important in the OSCs for facilitating electron and hole extraction from the bulk heterojunction (BHJ) photoactive layer by the respective electrodes. In this Review, we summarize the recent progress in the materials used as HTL and ETL in conventional and inverted OSCs on the basis of their effect on the PCE. Finally, the prospects of HTL and ETL materials for NFSMA-OSCs will be provided.

Efficient and Thermally Stable All‐Perovskite Tandem Solar Cells Using All‐FA Narrow‐Bandgap Perovskite and Metal‐oxide‐based Tunnel Junction

AbstractCommercialization of all‐perovskite tandem solar cells requires thermally stable narrow‐bandgap (NBG) perovskites and tunnel junction. However, the high content of methylammonium (MA) and organic hole transport layer used in NBG perovskite subcell undermine the thermal stability of all‐perovskite tandems. Here, thermally stable mixed lead‐tin NBG perovskite solar cells (PSCs) are developed by using only formamidinium (FA) for the A‐site cation. Solution‐processed indium tin oxide nanocrystals (ITO NCs) are deployed further to replace the conventional organic charge transport layer. Meanwhile, the ITO NCs layer simultaneously functions as a recombination layer in the tunnel junction, which simplifies the architecture of all‐perovskite tandem devices. The thermally stable all‐FA Pb‐Sn PSCs achieve a high power conversion efficiency (PCE) of 21.0%. With the thermally stable all‐FA NBG perovskite and optimized tunnel junction, a stabilized PCE of 26.3% is further obtained in all‐perovskite tandems. The unencapsulated tandem devices maintain >90% of their initial efficiencies after 212 h aging at 85 °C in the N2 atmosphere. The strategies herein offer a crucial step toward efficient and thermally stable all‐perovskite tandem solar cells.

Polymerizable Ammonium Salt Interlayer for Efficient and Stable NiOx-Based Perovskite Solar Cells

Although the research of formal perovskite solar cells (PSCs) has achieved great breakthroughs, the use of doped small-molecule organic hole transport layers limits the improvement of stability. PSCs with an inverted form show great potential in a more stable device structure. In this paper, a NiOx/3D perovskite interface in inverted PSCs was modified with a polymerizable amine salt (2-methylallylamine hydroiodide (CTBAI)) interlayer. The double bonds contained in CTBAI thermally induced polymerization of a thin film after heat treatment, resulting in the formation of amine salts with longer molecular chains. The modified layer can improve crystallinity and reduce defects in the film, as well as optimize the interface energy level and reduce interface recombination. The efficiency of NiOx-based inverted PSCs based on the optimized interface increased from 17.0% to 18.2%. After 280 h of MPP testing, the encapsulated device tested in ambient air (RH = 50–60%) demonstrated a robust light stabilization and maintained over 93% efficiency.

Sputtered Niox Films As Hole Transport Layers for FA-Based Perovskite Solar Cell Application

During the past years, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has increased from 3.8% to 25.7%, making them the best candidate for the next-generation photovoltaic devices. Two dominant PSC architectures have evolved, a regular n-i-p structure with mesoscopic or planar heterojunction and an inverted p-i-n planar structure. Compared to the regular n-i-p PSCs, the inverted p-i-n PSCs possess the advantages of lower synthesis temperature, no hysteretic effect and good compatibility with the tandem solar cells. For p-i-n PSCs, the hole transport layer (HTL) determines the hole transport efficiency and crystallinity of perovskite, so it plays a crucial role in the stacked devices. The conventional organic HTL of PEDOT:PSS-based PSCs can achieve satisfying PCEs, but may be able to impede the commercialization of perovskite photovoltaic devices because of their high price and acidity-induced poor stability. By comparison, the inorganic P-type NiOx with wide band gap exhibits low cost, superior chemical stability and high hole mobility without corrosion to perovskite layer. Unlike the most reported spin-coated NiOx nanoparticle films, we used sputtered NiOx as HTL for application in FA-based PSCs and achieved a PCE of 20.05%. After systematically optimizing the sputtering parameters, including power, time and argon flow rate, we obtained better crystal quality, better transparency, proper energy level, and higher hole mobility of NiOx film. Reducing the interstitial vacancies and defects in NiOx films attributes to decreased nonradiative recombination losses, which mainly cause the hole accumulation near the perovskite/NiOx interface. Finally, a champion device with open-circuit voltage (Voc) of 1.09 V, current density (Jsc) of 23.4 mA/cm2, fill factor (FF) of 78% and PCE of 20.05% are obtained. This work has important significance for preparation of large-area perovskite solar cell modules.

Organic Hole-Transport Layers for Efficient, Stable, and Scalable Inverted Perovskite Solar Cells.

Hole-transporting layers (HTLs) are an essential component in inverted, p-i-n perovskite solar cells (PSCs) where they play a decisive role in extraction and transport of holes, surface passivation, perovskite crystallization, device stability, and cost. Currently, the exploration of efficient, stable, highly transparent and low-cost HTLs is of vital importance for propelling p-i-n PSCs toward commercialization. Compared to their inorganic counterparts, organic HTLs offer multiple advantages such as a tunable bandgap and energy level, easy synthesis and purification, solution processability, and overall low cost. Here, recent progress of organic HTLs, including conductive polymers, small molecules, and self-assembled monolayers, as utilized in inverted PSCs is systematically reviewed and summarized. Their molecular structure, hole-transport properties, energy levels, and relevant device properties and resulting performances are presented and analyzed. A summary of design principles and a future outlook toward highly efficient organic HTLs in inverted PSCs is proposed. This review aims to inspire further innovative development of novel organic HTLs for more efficient, stable, and scalable inverted PSCs.

Surface engineering of ZnO nanoparticles with diethylenetriamine for efficient red quantum-dot light-emitting diodes

SummaryDue to the outstanding electron injection/transport capability of ZnO nanoparticles (NPs), quantum-dot light-emitting diodes (QLEDs) are commonly constructed by employing a hybrid device structure with ZnO electron-transporting layer and organic hole-transporting layer. However, the emission quenching of quantum dots and excessive electron injection induced by ZnO NPs also limits the device efficiency and operational stability. Here, diethylenetriamine (DETA) molecules as the ligands are introduced to modify the surface of ZnO NPs, which not only passivate the surface defects of ZnO but also suppress the overwhelming electron injection in the QLED. As a result, the device based on the DETA-modified ZnO NPs exhibits a peak external quantum efficiency of 23.7%, corresponding to an enhancement factor of 129% in comparison with that of the device with as-synthesized ZnO as the electron-transporting layer. The easy and feasible strategy may also be applicable to other photoelectric devices, such as solar cells and photodetectors.

Recent Advances in Nanostructured Inorganic Hole-Transporting Materials for Perovskite Solar Cells.

Organic-inorganic halide perovskite solar cells (PSCs) have received particular attention in the last decade because of the high-power conversion efficiencies (PCEs), facile fabrication route and low cost. However, one of the most crucial obstacles to hindering the commercialization of PSCs is the instability issue, which is mainly caused by the inferior quality of the perovskite films and the poor tolerance of organic hole-transporting layer (HTL) against heat and moisture. Inorganic HTL materials are regarded as promising alternatives to replace organic counterparts for stable PSCs due to the high chemical stability, wide band gap, high light transmittance and low cost. In particular, nanostructure construction is reported to be an effective strategy to boost the hole transfer capability of inorganic HTLs and then enhance the PCEs of PSCs. Herein, the recent advances in the design and fabrication of nanostructured inorganic materials as HTLs for PSCs are reviewed by highlighting the superiority of nanostructured inorganic HTLs over organic counterparts in terms of moisture and heat tolerance, hole transfer capability and light transmittance. Furthermore, several strategies to boost the performance of inorganic HTLs are proposed, including fabrication route design, functional/selectively doping, morphology control, nanocomposite construction, etc. Finally, the challenges and future research directions about nanostructured inorganic HTL-based PSCs are provided and discussed. This review presents helpful guidelines for the design and fabrication of high-efficiency and durable inorganic HTL-based PSCs.

Interface dipole at nickel oxide surface to enhance the photovoltage of perovskite solar cells

Inorganic nickel oxide (NiOx)-based inverted perovskite solar cells (PSCs) are reported to be more stable compared to those using organic hole transport layer materials. However, the Fermi level of NiOx is relatively away from the valence band of perovskite (PVK) layer, causing a large energy level shift at the NiOx/PVK interface and a weak built-in electric field strength. These increase the possibility of recombination, reduce the effective charge collection, seriously affect the efficiency of the device. In this work, an interface dipole with -CF3 end group is anchored to the NiOx/PVK interface, leading to a more matched energy level structure and greatly reducing the energy barrier at the NiOx/PVK interface. Moreover, the addition of Si-CF3 significantly improves the conductivity of NiOx and blunts the defects to large extent. The dipole interlayer significantly improves the built-in electric field and thus increases the photovoltage. Ultimately, the modified device achieves a score of 19.58% efficiency, much better than 17.98% of the control device.

A Conductive Molecular Semiconductor Composite with Over 160 °C Glass Transition Temperature for Heat‐Resistant Perovskite Solar Cells

AbstractUnder long‐term thermal stress, the decomposition of organic‐inorganic hybrid perovskite is a big challenge to realize stable and efficient perovskite solar cells (PSCs). Thereby, it is of pivotal importance to engineer an organic hole transport layer, which is featured not only by an excellent hole conduction but also by a high glass transition temperature. Here, a solution‐processible molecular semiconductor (T5H‐EP‐BMCA) is reported. The air‐doped composite of T5H‐EP‐BMCA presents a hole density of 6.5 × 1017 cm–3, a space‐charge‐limited current hole mobility of 5.1 × 10–4 cm2 V–1 s–1, and a direct‐current electrical conductivity of 30.6 µS cm–1. Moreover, the conductive composite owns a high glass transition temperature of 165 °C, a heat‐resistant morphology, and low gas permeability coefficients. These joint attributes allow for the fabrication of 21.0%‐efficiency, 85 °C‐durable PSC by controlling the thermal decomposition of perovskite.

High-efficient hole-transport-material-free carbon-based all-inorganic perovskite solar cells using Cs-doped TiO2 nanorods array as the electron transport layer

Vertical-oriented Cs-doped rutile TiO2 nanorod (Cs-TiO2 NR) arrays were prepared without a seed layer through the hydrothermal method. One-dimension TiO2 nanorod (TiO2 NR) arrays not only provide a direct and fast channel for charge transfer but also increase the perovskite loading amount. Further research shows that the conduction band minimum of Cs-TiO2 NRs increases from − 3.94 eV to − 3.86 eV when compared with the pristine TiO2 NRs, which favors the positive band alignment at the ETL/perovskite interface and reduces the carrier recombination and energy loss. Furthermore, we simultaneously replaced the expensive and unstable organic hole transport layer and noble metal electrode with a carbon electrode for the purpose of reducing the cost of the PSCs. The study proves that Cs-TiO2 NRs not only improve the energy level arrangement at the ETL/perovskite interface but also reduce the density of defect states at the interface and increase carrier lifetime. The hole-transport-material-free carbon-based all-inorganic FTO/Cs-TiO2 NRs/CsPbI2.25Br0.75/C solar devices exhibited a high-power conversion efficiency (PCE) of 12.72%, showing a 16% increase in PCE when compared with the control device. This work opens the door to the preparation of high-efficiency hole-transport-material-free carbon-based all-inorganic PSCs via the energy level calibration engineering.

Efficient Perovskite Light‐Emitting Diodes with a Siloxane‐Blended Organic Hole Transport Layer

Metal halide perovskite light‐emitting diodes (LEDs) are promising for future display applications because of their excellent advantages, such as high external quantum efficiency, emission color tunability, and high emission color purity. Although solution processing widely used for perovskite film fabrication is an additional advantage, there are cases in which fabricating a perovskite‐emitting layer with spin‐coating results in the dissolution of an underlying organic hole transport layer (HTL). As a result, since a perovskite layer comes into partial contact with an indium tin oxide (ITO) anode layer, excited states formed in a perovskite‐emitting layer are quenched by charge transfer to ITO. In this study, it is shown that adding tetraethyl orthosilicate (TEOS) into a HTL material of poly(N‐vinylcarbazole) (PVCz) is an effective method used to overcome this issue. Upon heating, the hydrolysis reaction of TEOS molecules takes place in PVCz films to form a siloxane network, which makes PVCz films insoluble and, therefore, alleviates the excited‐state quenching. It is demonstrated that using the siloxane‐blended PVCz HTL increases external quantum efficiencies of perovskite LEDs to 15.4 ± 0.3% from the original 10.4 ± 0.3% by about 1.5 times.

Balancing charge injection in quantum dot light-emitting diodes to achieve high efficienciy of over 21%

Quantum dot light-emitting diodes (QLEDs) have attracted considerable attention in displays owing to their high color purity, wide gamut, narrow emission band, and solution-processed characteristics. However, a major problem of the unbalanced carrier (electrons and holes) injection in QLEDs deteriorates their performance. Here, we balanced the charge injection in QLEDs by optimizing the carrier transport layers. Different organic hole transport layers (HTLs) with a suitable thickness were employed to match the electron transport layer (ETL) of ZnO. Mg2+ was doped into the ZnO (MZO) ETL to decrease the electron mobility and match the hole mobility of the HTL. Consequently, the QLEDs exhibited an excellent external quantum efficiency (EQE) of 21.10% at a luminance of 4661 cd m−2. In the luminance range of 100–30,000 cd m−2, EQE roll-off was considerably low, and more than 80% of the initial EQE value could be maintained, indicating less Auger recombination because of the balanced carrier injection. This work reveals that compared with energy level matching, the charge transfer capability of the transport layers is more instrumental in the charge balance regulation of QLED devices.

Oxidized Nickel to Prepare an Inorganic Hole Transport Layer for High-Efficiency and Stability of CH3NH3PbI3 Perovskite Solar Cells

In this study, we report a perovskite solar cell (PSC) can be benefited from the high quality of inorganic nickel oxide (NiOx) as a hole transport layer (HTL) film fabricated from the physical vapor deposition (PVD) process. The power conversion efficiency (PCE) of PSC is found to depend on the thickness of NiOx HTL. The NiOx thickness is optimized via quantitative investigation of the structure, optical and electrical properties. With an active area of 11.25 cm2, a PSC module (25 cm2) with a PCE of 15.1% is demonstrated, while statistically averaged PCE = 18.30% with an open voltage (Voc) 1.05 V, short-circuit current density (Jsc) 23.89 mA/cm2, and fill factor (FF) 72.87% can be achieved from 36 devices with smaller active areas of 0.16 cm2. After the stability test at 40% relative humidity (RH) and 25 °C for 1200 h, the highest performance NiOx-based PSC is shown to be about 1.2–1.8 times superior to PEDOT:PSS organic HTL based PSC at the same environment.