Enhanced Efficiency and Stability of Perovskite Solar Cells via Anti-Solvent Treatment in Two-Step Deposition Method

Utilizing Machine Learning and Diode Physics to Investigate the Effects of Stoichiometry on Photovoltaic Performance in Sequentially Processed Perovskite Solar Cells

Organic-inorganic metal halide perovskite solar cells are renowned for their extensive solution processability, although the production of uniformly crystalline perovskite films can necessitate intricate deposition methods. In our study, we harmonized Shockley diode-based numerical analysis with machine learning techniques to extract the device characteristics of perovskite solar cells and optimize their photovoltaic performance in light of the experimental variables. The application of the Shockley diode equation facilitated the extraction of photovoltaic parameters and the prediction of power conversion efficiencies, thus aiding the understanding of device physics and charge recombination. Through machine learning, specifically Gaussian process regression, we trained models on current-voltage curves sensitive to variations in fabrication conditions, thereby pinpointing the optimal settings for enhanced device performance. Our multifaceted approach not only clarifies the interplay between experimental conditions and device performance but also streamlines the optimization process, diminishing the need for exhaustive trial-and-error experiments. This methodology holds substantial promise for advancing the development and fine-tuning of next-generation perovskite solar cells.

Greatly improved photoresponse in the MAPbBr3/Si heterojunction by introducing an ITO layer and optimizing MAPbBr3 layer thickness

In this paper, a CH₃NH₃(MA)PbBr₃/Si heterojunction photodetector (PD) is prepared, and a simple method is proposed to improve the performance by introducing an ITO conductive layer and modulating thickness of the MAPbBr₃ layer. The results indicate that the MAPbBr₃/Si heterojunction PD exhibits an ultra-broadband photoresponse ranging from 405 to 1064 nm, and excellent performances with the responsivity (R) of 0.394 mA/W, detectivity (D) of 0.11×10¹⁰ Jones, and response times of ∼2176/∼257 ms. When adding the ITO layer, the R and D are greatly improved to 0.426 A/W and 5.17×10¹⁰ Jones, which gets an increment of 1.08×10⁵% and 4.7×10³%, respectively. Meanwhile, the response times are reduced to ∼130/∼125 ms, and a good environmental stability is obtained. Moreover, it is found that the photoresponse is strongly dependent on the thickness of the MAPbBr₃ layer. By modulating the MAPbBr₃ layer thickness from ∼85 to ∼590 nm, the performances are further improved with the best R of ∼0.87 A/W, D of ∼1.92×10¹¹ Jones, and response times of ∼129/∼130 ms achieved in the ∼215 nm-thick PD.

Investigations of Fused Deposition Modeling for Perovskite Active Solar Cells

The advent of Fused Deposition Modeling (FDM; or 3D printing) has significantly changed the way many products are designed and built. It has even opened opportunities to fabricate new products on-site and on-demand. In addition, parallel efforts that introduce new materials into the FDM process have seen great advances as well. New additives have been demonstrably utilized to achieve thermal, electrical, and structural property improvements. This combination of fabrication flexibility and material additives make FDM an ideal candidate for investigation of perovskite materials in new solar cell efforts. In this work, we fabricate and characterize a perovskite-based solar cell polymer designed for the FDM fabrication processes. Perovskite solar cells have garnered major research interest since their discovery in 2009. Perovskites, specifically methylammonium lead iodide, offer beneficial properties to solar cell fabrication such as long minority charge carrier distance, high light absorption, and simple fabrication methods. Despite the great potential of these materials, however, stability remains an issue in solar cell utilization as the material degrades under ultraviolet light, exposure to oxygen and water, as well as increased temperatures. To mitigate degradation, different fabrication methods have been utilized. Additionally, multiple groups have utilized encapsulation methods post-fabrication and in situ solution processed integration of polymer materials into the solar cell to prevent degradation. In this paper, we leverage the unique ability of FDM to encapsulate perovskite materials and yield a MAPbI₃-PCL solar material as the active layer for solar cell use. In this manner, increased ability to resist UV light degradation and material stability from other environmental factors can be achieved. This study provides characterization of the material via multiple techniques like SEM (Scanning Electron Microscopy) and XRD (X-ray Diffraction) as well as absorbance, transmittance, and photocurrent response. Investigations of processing on perovskite degradation as well as initial solar simulated response are recorded. Unique aspects of the resulting material and process are noted including improved performance with increased operating temperature. Increased electron–hole pair generation is observed for 200 μm FDM-printed PCL film, achieving a 45% reduction in resistance under peak incident flux of 590 W/m2 with the addition of MAPbl₃. This work establishes insight into the use of FDM for full solar cell fabrication and points to the next steps of research and development in this growing field.

Efficient Planar Perovskite Solar Cells with Carbon Quantum Dot-Modified spiro-MeOTAD as a Composite Hole Transport Layer

In perovskite solar cells (PSCs), the hole-transport layer (HTL) plays an essential role in effective charge transport and extraction from the photoexcited perovskite, thus being significant for overall power conversion efficiency (PCE) and operational stability. So far, spiro-MeOTAD has been the most widely used HTL despite its inherent drawbacks, such as highly hygroscopic nature, poor conductivity, and mismatched energy-level alignment with the perovskite active layer. Here, a spiro-MeOTAD-based composite HTL modified by microwave method-synthesized carbon quantum dots (CQDs) was proposed and demonstrated as a promising HTL candidate for high-performance PSCs. The results demonstrated that the CQDs/spiro-MeOTAD composite HTL possesses several appealing characteristics for PSC applications, such as suitable energy levels for hole extraction, passivated interfacial trap states, and reduced recombination losses. Consequently, as compared to the control one using an unmodified spiro-MeOTAD HTL, (FAPbI₃)_0.95(MAPbBr₃)_0.05-based planar PSCs with composite HTL exhibit notably enhanced PCE and operational stability. Remarkably, an encouraging PCE of 20.41% was achieved for the champion device, and much improved operational stability was also demonstrated under continuous AM1.5 illumination with maximum power point (MPP) tracking conditions.

Preparation of low-cost perovskite solar cells with high-quality perovskite films in an ambient atmosphere

High-quality perovskite films are extremely crucial to obtain perovskite solar cells with excellent photovoltaic performance, especially for carbon-based hole transport materials (HTM)-free perovskite solar cells. In this work, a facile and low-cost double two-step method (DT-method) is developed to prepare uniform and pinhole-free CH₃NH₃PbI₃perovskite films in an ambient atmosphere by utilizing the dissolution-recrystallization of PbI₂in DMF. That is to spin-coat PbI₂and CH₃NH₃I solution sequentially onto pristine perovskite films prepared by the conventional two-step method. The solar cells fabricated by the DT-method show a dramatic performance improvement, includingV_oc,J_sc, and fill factor reach 0.85 V, 15.56 mA cm^-2, and 0.58 respectively, which increase power conversion efficiency from 3.93% to 7.58% compared with the conventional two-step method. The improvement in performance and stability of solar cells is mainly due to the higher coverage of perovskite films onto the underlying mesoporous TiO₂layer and a negligible amount of PbI₂residue, which can effectively reduce charge recombination and promote the rapid transfer of charge carriers. In summary, this work presents a process for preparing carbon-based HTM-free perovskite solar cells (PSCs) in a high-humidity atmospheric environment (60%-85%). This simple device structure and preparation condition can greatly reduce the production threshold and cost of PSCs.

Beneficial effects of cesium acetate in the sequential deposition method for perovskite solar cells

The cesium cation (Cs+) is widely used as a dopant for highly efficient and stable formamidinium lead tri-halide perovskite (FAPbX3, X = I, Br, Cl) solar cells. Herein, we introduce a small amount of cesium acetate (CsAc) that can effectively stabilize FAMAPbI3 under thermal- and light illumination-stress. We show that incorporated Cs+ leads to relaxation of strain in the perovskite layer, and that Ac- forms a strong intermediate phase with PbI2, which can help the intercalation of the PbI2 film with Cs+ and cation halide (FAI, MAI, MACl) in the sequential deposition process. The addition of CsAc reduces the trap density in the resulting perovskite layers and extends their carrier lifetime. The CsAc-modified perovskite solar cells show less hysteresis phenomena and enhanced operational and thermal stability in ambient conditions. Our findings provide insight into how dopants and synthesis precursors play an important role in efficient and stable perovskite solar cells.

Electrical Loss Management by Molecularly Manipulating Dopant-free Poly(3-hexylthiophene) towards 16.93 % CsPbI2 Br Solar Cells

Inorganic cesium lead halide perovskites offer a pathway towards thermally stable photovoltaics. However, moisture-induced phase degradation restricts the application of hole transport layers (HTLs) with hygroscopic dopants. Dopant-free HTLs fail to realize efficient photovoltaics due to severe electrical loss. Herein, we developed an electrical loss management strategy by manipulating poly(3-hexylthiophene) with a small molecule, i.e., SMe-TATPyr. The developed P3HT/SMe-TATPyr HTL shows a three-time increase of carrier mobility owing to breaking the long-range ordering of "edge-on" P3HT and inducing the formation of "face-on" clusters, over 50 % decrease of the perovskite surface defect density, and a reduced voltage loss at the perovskite/HTL interface because of favorable energy level alignment. The CsPbI₂ Br perovskite solar cell demonstrates a record-high efficiency of 16.93 % for dopant-free HTL, and superior moisture and thermal stability by maintaining 96 % efficiency at low-humidity condition (10-25 % R. H.) for 1500 hours and over 95 % efficiency after annealing at 85 °C for 1000 hours.

Orientation-Controlled (h0l) PbI2 Crystallites Using a Novel Pb-Precursor for Facile and Quick Sequential MAPbI3 Perovskite Deposition

Organic-inorganic hybrid lead halide perovskites have shown significant progress in the last few years having achieved efficiencies over 25% at the lab scale. The sequential deposition technique has provided a robust approach in the perovskite film fabrication. However, obtaining a reproducible and quality perovskite film has always been challenging because of the highly crystalline and ordered (001) oriented underlying PbI₂ film. Here, we report a simple solution approach to fabricate a PbI₂ residue-free, superior grade perovskite film by using a compositional engineered PbI₂-precursor solution. We demonstrate that the Pb-precursor film crystallized into a R-centered Hexagonal metric lattice with (h0l), (hk0), and (00l) orientations provides a more efficient and quicker conversion into perovskites compared to conventional (001) oriented 2H-PbI₂. A porous and multi-oriented PbI₂ film is prepared by rationally incorporating a volumetric fraction of Pb(Ac)₂·3H₂O in the typical PbI₂/dimethylformamide precursor solution, which significantly improves the surface features of PbI₂ as well as the structural properties. As a result, a compact, smooth, and large grain perovskite can be obtained by accomplishing a full conversion with comparatively much less reaction time. Furthermore, a comprehensive mechanism of structural modification of PbI₂ and the role of its orientation in ameliorating the reaction kinetics has been demonstrated.

Unveiling the Morphology Effect on the Negative Capacitance and Large Ideality Factor in Perovskite Light-Emitting Diodes

Perovskite light-emitting diodes have almost reached the threshold for potential commercialization within a few years of research. However, there are still some unsolved puzzles such as large ideality factor and the presence of large negative capacitance especially at the low-frequency regime yet to be addressed. Here, we have fabricated a methylammonium lead tri-bromide perovskite n-i-p structure for light-emitting diodes from a smooth and textured emissive layer and demonstrated for the first time that these two factors are strongly dependent on the perovskite film morphology. Bias-dependent capacitance measurement also reveals the transition between negative to positive capacitance in textured films at the low-frequency regime. We have observed an anomalous capacitive behavior at the mid-frequency regime in smooth perovskite films but not in textured films. The relatively large ideality factor and anomalous capacitive behavior observed in perovskite light-emitting diodes are due to the presence of strong coupling between ions and electrons near the electrode interface. Therefore, the ideality factor and anomalous capacitance at the mid-frequency regime can be decreased by minimizing electronic-ionic coupling in textured perovskite films, while light outcoupling can be improved significantly.

Composite Encapsulation Enabled Superior Comprehensive Stability of Perovskite Solar Cells

Solar cells based on organometal hybrid perovskites have exhibited promising commercialization potential owing to their high efficiency and low-cost manufacturing. However, the poor outdoor operational stability of perovskite solar cells restricted their practical application, and moisture permeation and organic compounds volatilization are realized as the main factors accelerating performance degradation. Herein, we developed a composite encapsulation, by sequentially depositing a compact Al₂O₃ layer and a hydrophobic 1H,1H,2H,2H-perfluorodecyltrichlorosilane layer on the completed device, to efficiently circumvent vapor permeability. Thus, the stability of the encapsulated perovskite solar cells was systematically investigated under simulated operational conditions. It was found that the MAPbI₃ perovskite was prone to decay into solid PbI₂ and organic vapor at high temperature or upon light illumination, and the decomposition was reversible in a well-encapsulated environment, resulting in reversible performance degradation and recovery. The enhanced thermal stability was ascribed to the competition between the perovskite decomposition and reverse synthesis. The as-prepared high-quality, multilayered encapsulation scheme demonstrated superior sealing property, and no obvious performance decline was observed when the device was stored under ambient air, continuous light illumination, double 85 condition (85 °C, 85% humidity), or even water immersion. Therefore, this work paves the way for a scalable and robust encapsulation strategy feasible to hybrid perovskite optoelectronics in a reproducible manner.

Incorporation of Nickel Ions to Enhance Integrity and Stability of Perovskite Crystal Lattice for High-Performance Planar Heterojunction Solar Cells

Enhancement of integrity and stability of crystal lattice are highly challenging for polycrystalline perovskite films. In this work, a strategy of incorporation of nickel (Ni) ions is presented to modulate the crystal structure of the CH₃NH₃PbI₃ perovskite film. A broad range of experimental characterizations reveal that the incorporation of Ni ions can substantially eliminate the intrinsic halide vacancy defects, since Ni ions have a strong preference for octahedral coordination with halide ions, resulting in significantly improved integrity and short-range order of crystal lattice. Moreover, it is also demonstrated that the stronger chemical bonding interaction between Ni ions and halide ions as well as organic group can improve the stability of the perovskite material. Simultaneously, the surface morphology of the perovskite thin film is also improved by the incorporation of nickel ions. As a result, a planar heterojunction perovskite solar cell incorporated with 1.5% Ni exhibits a power conversion efficiency of 18.82%, which is improved by 25% compared with 14.92% for the pristine device. Simultaneously, the device formed incorpration of 1.5% Ni shows remarkable stability with 90% of the initial efficiency after storage in an air environment for 800 h. The studies provide a new insight into metal-incorporated perovskite materials for various optoelectronic applications.

High Efficiency and Stability of Inverted Perovskite Solar Cells Using Phenethyl Ammonium Iodide-Modified Interface of NiOx and Perovskite Layers

Hole transport layer NiO_x-based inverted perovskite solar cells (PSCs) have advantages of simple fabrication, low temperature, and low cost. Furthermore, the p-type NiO_x material compared to that of typical n-type SnO_x for PSCs has better photostability potential due to its lower photocatalytic ability. However, the NiO_x layer modified by some typical materials show relatively simple functions, which limit the synthesized performance of NiO_x-based inverted PSCs. Phenethyl ammonium iodide (PEAI) was introduced to modify the NiO_x/perovskite interface, which can synchronously contribute to better crystallinity and stability of the perovskite layer, passivating interface defects, formed quasi-two-dimensional PEA₂PbI₄ perovskite layers, and superior interface contact properties. The PCEs of PSCs with the PEAI-modified NiO_x/perovskite interface was obviously increased from 20.31 from 16.54% compared to that of the reference PSCs. The PSCs with PEAI modification remained 75 and 72% of the original PCE values aging for 10 h at 85 °C and 65 days in a relative humidity of 15%, which are superior to the original PCE values (47 and 51%, respectively) for the reference PSCs. Therefore, PSCs with the PEAI-modified NiO_x/perovskite interface show higher PCEs and better thermal stability and moisture resistance.

Effects of Illumination Direction on the Surface Potential of CH3NH3PbI3 Perovskite Films Probed by Kelvin Probe Force Microscopy

The development of organic-inorganic hybrid perovskite solar cells requires critical understanding in the charge-carrier behaviors in the perovskite light absorbers and devices. Kelvin probe force microscopy (KPFM) has been applied as a powerful tool to probe the electrical potential distribution of perovskite films and devices, providing fundamental insights into their charge-carrier properties. When measuring the material photoresponses, various approaches have been employed to illuminate the samples. Here, we measured the surface potential of the layer in the regular mesoporous structure (CH₃NH₃PbI₃/m-TiO₂/c-TiO₂/FTO) and inverted planar structure (CH₃NH₃PbI₃/NiO/FTO) devices via KPFM. Effects of two representative illumination methods are compared-illumination from top, and from underneath through the transparent glass substrate. By comparing the variation in surface potential under two illumination methods, the surface potential of the perovskite-absorbing layer in a regular structure is higher than that in the inverted structure. The potential difference in two structures implies that the photogenerated charge carriers are injected to the TiO₂ electron-transport layer and NiO hole-transport layer, resulting in positive charges and negative charges accumulated in the perovskite-absorbing layer. We demonstrated that the illumination direction has an impact on the surface potential measurement. For the CH₃NH₃PbI₃/TiO₂ structure, illumination from underneath facilitates a larger potential change. While for the CH₃NH₃PbI₃/NiO structure with insensitive photoresponse in potential change, the illumination direction has a minor effect.

A potassium thiocyanate additive for hysteresis elimination in highly efficient perovskite solar cells

Potassium thiocyanate as a cheap additive effectively eliminates the hysteresis effect of perovskite solar cells.

Solution evaporation processed high quality perovskite films

Organic-inorganic hybrid perovskite solar cells (PSCs), due to their high power conversion efficiency (PCE) and low cost, have been considered as one of the most promising photovoltaic devices. Well-distributed large-grain perovskite crystals play an important role for light adsorption and charge transfer. While, high quality perovskite crystals closely relate to the preparation method. Generally, the preparation of perovskite films requires a nitrogen atmosphere and toxic anti-solvents, which hinder their practical applications. Here, we reported a novel and simple solution evaporation process followed with a methylammonium iodide (MAI) solution immersion to prepare high quality perovskite films. Porous lead iodide (PbI₂) films were firstly formed by evaporation of PbI₂ precursor solution. The obtained porous PbI₂ films were completely transformed into well-distributed large-grain perovskite films after a quick MAI solution immersion. As a result, the corresponding PCE was enhanced by 30% compared to that prepared with a regular sequential deposition. This solution evaporation method provides a convenient and practical way for preparing high-quality perovskite films.

Antisolvent with an Ultrawide Processing Window for the One-Step Fabrication of Efficient and Large-Area Perovskite Solar Cells

Photovoltaic technologies based on perovskite absorber materials have led this optoelectronic field into a brand-new horizon. However, the present antisolvents used in the one-step spin-coating method always encounter problems with the very narrow process window. Herein, anisole is introduced into the one-step spin-coating method, and the technology is developed to fabricate perovskite thin films with ultrawide processing window with a dimethylformamide (DMF):dimethyl sulfoxide (DMSO) ratio varying from 6:4 to 9:1 in the precursor solution, anisole dripping time ranging from 5 to 25 s, and an antisolvent volume varying from 0.1 to 0.9 mL. Perovskite thin films as large as 100 cm² are successfully fabricated using this method. Maximum photoelectric conversion efficiencies of 19.76% for small-area (0.14 cm² ) and 17.39% for large-area (1.08 cm² ) perovskite solar cell devices are obtained. It is also found that there are intermolecular hydrogen-bonding forces between anisole and DMF/DMSO that play critical roles in the wide process window. These results provide a deeper understanding of the crystallizing procedure of perovskite during the one-step spin-coating process.

Hydrophobic Polystyrene Passivation Layer for Simultaneously Improved Efficiency and Stability in Perovskite Solar Cells

The major restraint for the commercialization of the high-performance hybrid metal halide perovskite solar cells is the long-term stability, especially at the infirm interface between the perovskite film and organic charge-transfer layer. Recently, engineering the interface between the perovskite and spiro-OMeTAD becomes an effective strategy to simultaneously improve the efficiency and stability in the perovskite solar cells. In this work, we demonstrated that introducing an interfacial polystyrene layer between the perovskite film and spiro-OMeTAD layer can effectively improve the perovskite solar cells photovoltaic performance. The inserted polystyrene layer can passivate the interface traps and defects effectively and decrease the nonradiative recombination, leading to enhanced photoluminescence intensity and carrier lifetime, without compromising the carrier extraction and transfer. Under the optimized condition, the perovskite solar cells with the polystyrene layer achieve an enhanced average power efficiency of about 19.61% (20.46% of the best efficiency) from about 17.63% with negligible current density-voltage hysteresis. Moreover, the optimized perovskite solar cells with the hydrophobic polystyrene layer can maintain about 85% initial efficiency after 2 months storage in open air conditions without encapsulation.

Dependence of Acetate-Based Antisolvents for High Humidity Fabrication of CH3NH3PbI3 Perovskite Devices in Ambient Atmosphere

High-efficiency perovskite solar cells (PSCs) need to be fabricated in the nitrogen-filled glovebox by the atmosphere-controlled crystallization process. However, the use of the glovebox process is of great concern for mass level production of PSCs. In this work, notable efficient CH₃NH₃PbI₃ solar cells can be obtained in high humidity ambient atmosphere (60-70% relative humidity) by using acetate as the antisolvent, in which dependence of methyl, ethyl, propyl, and butyl acetate on the crystal growth mechanism is discussed. It is explored that acetate screens the sensitive perovskite intermediate phases from water molecules during perovskite film formation and annealing. It is revealed that relatively high vapor pressure and high water solubility of methyl acetate (MA) leads to the formation of highly dense and pinhole free perovskite films guiding to the best power conversion efficiency (PCE) of 16.3% with a reduced hysteresis. The devices prepared using MA showed remarkable shelf life stability of more than 80% for 360 h in ambient air condition, when compared to the devices fabricated using other antisolvents with low vapor pressure and low water solubility. Moreover, the PCE was still kept at 15.6% even though 2 vol % deionized water was added in the MA for preparing the perovskite layer.

Efficient and ultraviolet durable planar perovskite solar cells via a ferrocenecarboxylic acid modified nickel oxide hole transport layer

Planar perovskite solar cells (PSCs) that use nickel oxide (NiO_x) as a hole transport layer have recently attracted tremendous attention because of their excellent photovoltaic efficiencies and simple fabrication. However, the electrical conductivity of NiO_x and the interface contact properties of the NiO_x/perovskite layer are always limited for the NiO_x layer fabricated at a relatively low annealing temperature. Ferrocenedicarboxylic acid (FDA) was firstly introduced to modify a p-type NiO_x hole transport layer in PSCs, which obviously improves the crystallization of the perovskite layer and hole transport and collection abilities and reduces carrier recombination. PSCs with a FDA modified NiO_x layer reached a PCE of 18.20%, which is much higher than the PCE (15.13%) of reference PSCs. Furthermore, PSCs with a FDA interfacial modification layer show better UV durability and a hysteresis-free effect and still maintain the original PCE value of 49.8%after being exposed to UV for 24 h. The enhanced performance of the PSCs is attributed to better crystallization of the perovskite layer, the passivation effect of FDA, superior interface contact at the NiO_x/perovskite layers and enhancement of the electrical conductivity of the FDA modified NiO_x layer. In addition, PSCs with FDA inserted at the interface of the perovskite/PCBM layers can also improve the PCE to 16.62%, indicating that FDA have dual functions to modify p-type and n-type carrier transporting layers.

Efficient Yttrium(III) Chloride-Treated TiO2 Electron Transfer Layers for Performance-Improved and Hysteresis-Less Perovskite Solar Cells

Hybrid organic-inorganic metal halide perovskite solar cells have attracted widespread attention, owing to their high performance, and have undergone rapid development. In perovskite solar cells, the charge transfer layer plays an important role for separating and transferring photogenerated carriers. In this work, an efficient YCl₃ -treated TiO₂ electron transfer layer (ETL) is used to fabricate perovskite solar cells with enhanced photovoltaic performance and less hysteresis. The YCl₃ -treated TiO₂ layers bring about an upward shift of the conduction band minimum (E_CBM ), which results in a better energy level alignment for photogenerated electron transfer and extraction from the perovskite into the TiO₂ layer. After optimization, perovskite solar cells based on the YCl₃ -treated TiO₂ layers achieve a maximum power conversion efficiency of about 19.99 % (19.29 % at forward scan) and a steady-state power output of about 19.6 %. Steady-state and time-resolved photoluminescence measurements and impedance spectroscopy are carried out to investigate the charge transfer and recombination dynamics between the perovskite and the TiO₂ electron transfer layer interface. The improved perovskite/TiO₂ ETL interface with YCl₃ treatment is found to separate and extract photogenerated charge rapidly and suppress recombination effectively, which leads to the improved performance.

Efficiency enhancement in inverted planar perovskite solar cells by synergetic effect of sulfated graphene oxide (sGO) and PEDOT:PSS as hole transporting layer

We report a simple solution route for preparing a sGO-PEDOT composite HTL by combining solution-processable sGO with commercialized PEDOT:PSS solution. The PSCs based on these sGO-PEDOT composite HTLs were systematically investigated.