Organometal Halide Perovskite Solar Cells Research Articles

Chemical Reaction of FA Cations Enables Efficient and Stable Perovskite Solar Cells.

Organometal halide perovskite solar cells (PSCs) have received great attention owing to a rapid increase in power conversion efficiency (PCE) over the last decade. However, the deficit of long-term stability is a major obstacle to the implementation of PSCs in commercialization. The defects in perovskite films are considered as one of the primary causes. To address this issue, isocyanic acid (HNCO) is introduced as an additive into the perovskite film, in which the added molecules form covalent bonds with FA cations via a chemical reaction. This chemical reaction gives rise to an efficient passivation on the perovskite film, resulting in an improved film quality, a suppressed non-radiation recombination, a facilitated carrier transport, and optimization of energy band levels. As a result, the HNCO-based PSCs achieve a high PCE of 24.41% with excellent storage stability both in an inert atmosphere and in air. Different from conventional passivation methods based on coordination effects, this work presents an alternative chemical reaction for defect passivation, which opens an avenue toward defect-mitigated PSCs showing enhanced performance and stability.

Stability enhancement of perovskite solar cells using multifunctional inorganic materials with UV protective, self cleaning, and high wear resistance properties

Organometal halide perovskite solar cells have reached a high power conversion efficiency of up to 25.8% but suffered from poor long-term stability against environmental factors such as ultraviolet irradiation and humidity of the environment. Herein, two different multifunctional transparent coatings containing AZO and ZnO porous UV light absorbers were employed on the front of the PSCs. This strategy is designed to improve the long-term stability of PSCs against UV irradiation. Moreover, the provided coatings exhibit two additional roles, including self-cleaning and high wear resistance. In this regard, AZO coating showed higher wear resistance compared to the ZnO coating. The photocatalytic self-cleaning properties of these prepared coatings make them stable against environmental pollutants. Furthermore, appropriate mechanical properties such as high hardness and low coefficient of friction that leads to high resistance against wear are other features of these coatings. The devices with AZO/Glass/FTO/meso-TiO2/Perovskite/spiro/Au and ZnO/Glass/FTO/meso-TiO2/Perovskite/spiro/Au configurations maintained 40% and 30% of their initial performance for 100 h during 11 days (9 h per day) against the UV light with the high intensity of 50 mW cm-2 which is due to higher absorption of AZO compared with ZnO in the ultraviolet region. Since AZO has a higher light transmission in the visible region in comparison to ZnO, perovskite cells with AZO protective layers have higher efficiency than perovskite cells with ZnO layers. It is worth noting that the mentioned features make these coatings usable for cover glass in all types of solar cells.

Long-chain organic molecules enable mixed dimensional perovskite photovoltaics: a brief view.

The remarkable optoelectronic properties of organometal halide perovskite solar cells have captivated significant attention in the energy sector. Nevertheless, the instability of 3D perovskites, despite their extensive study and attainment of high-power conversion efficiency, remains a substantial obstacle in advancing PSCs for practical applications and eventual commercialization. To tackle this issue, researchers have devised mixed-dimensional perovskite structures combining 1D and 3D components. This innovative approach entails incorporating stable 1D perovskites into 3D perovskite matrices, yielding a significant improvement in long-term stability against various challenges, including moisture, continuous illumination, and thermal stress. Notably, the incorporation of 1D perovskite yields a multitude of advantages. Firstly, it efficiently passivates defects, thereby improving the overall device quality. Secondly, it retards ion migration, a pivotal factor in degradation, thus further bolstering stability. Lastly, the inclusion of 1D perovskite facilitates charge transport, ultimately resulting in an elevated device efficiency. In this succinct review, we thoroughly encapsulate the recent progress in PSCs utilizing 1D/3D mixed-dimensional architectures. These advancements encompass both stacked bilayer configurations of 1D/3D structures and mixed monolayer structures of 1D/3D. Additionally, we tackle critical challenges that must be surmounted and offer insights into the prospects for further advancements in this domain.

Elucidating the Mechanism of Self-Healing in Hydrogel-Lead Halide Perovskite Composites for Use in Photovoltaic Devices.

Since the emergence of organometal halide perovskite (OMP) solar cells, there has been growing interest in the benefits of incorporating polymer additives into the perovskite precursor, in terms of both photovoltaic device performance and perovskite stability. In addition, there is interest in the self-healing properties of polymer-incorporated OMPs, but the mechanisms behind these enhanced characteristics are still not fully understood. Here, we study the role of poly(2-hydroxyethyl methacrylate) (pHEMA) in improving the stability of methylammonium lead iodide (MAPI, CH3NH3PbI3) and determine a mechanism for the self-healing of the perovskite-polymer composite following exposure to atmospheres of differing relative humidity, using photoelectron spectroscopy. Varying concentrations of pHEMA (0-10 wt %) are incorporated into a PbI2 precursor solution during the conventional two-step fabrication method for producing MAPI. It is shown that the introduction of pHEMA results in high-quality MAPI films with increased grain size and reduced PbI2 concentration compared with pure MAPI films. Devices based on pHEMA-MAPI composites exhibit an improved photoelectric conversion efficiency of 17.8%, compared with 16.5% for a pure MAPI device. pHEMA-incorporated devices are found to retain 95.4% of the best efficiency after ageing for 1500 h in 35% RH, compared with 68.5% achieved from the pure MAPI device. The thermal and moisture tolerance of the resulting films is investigated using X-ray diffraction, in situ X-ray photoelectron spectroscopy (XPS), and hard XPS (HAXPES). It is found that exposing the pHEMA films to cycles of 70 and 20% relative humidity leads to a reversible degradation, via a self-healing process. Angle-resolved HAXPES depth-profiling using a non-destructive Ga Kα source shows that pHEMA is predominantly present at the surface with an effective thickness of ca. 3 nm. It is shown using XPS that this effective thickness reduces with increasing temperature. It is found that N is trapped in this surface layer of pHEMA, suggesting that N-containing moieties, produced during reaction with water at high humidity, are trapped in the pHEMA film and can be reincorporated into the perovskite when the humidity is reduced. XPS results also show that the inclusion of pHEMA enhances the thermal stability of MAPI under both UHV and 9 mbar water vapor pressure.

Effect of Hole Transport Materials and Their Dopants on the Stability and Recoverability of Perovskite Solar Cells on Very Thin Substrates after 7 MeV Proton Irradiation

AbstractThe drastic reduction in launch and manufacturing costs of space hardware has facilitated the emergence of "commercial" space. Radiation‐hard organometal halide perovskite solar cells (PSCs) with low‐cost and high‐efficiency potentials are promising for space applications.High‐efficiency PSCs are tested with different hole transport materials (HTMs) and dopants on 175µm sapphire substrates under 7MeV‐proton‐irradiation‐tests at accumulated fluences of 1011, 1012, and 1013 protons cm−2. While all cells retain >90% of their initial power conversion efficiencies (PCEs) after 1011 protons cm−2 irradiation, PSCs that have tris(pentafluorophenyl)borane (TPFB) as the HTM dopant and poly[bis(4‐phenyl)(2,5,6‐trimethylphenyl) amine (PTAA) or PTAA:C8BTBT (C8BTBT = 2,7‐Dioctyl[1]benzothieno[3,2‐b][1]benzothiophene) as the HTM are more tolerant to higher‐fluence radiation than their counterparts with the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dopant and the 2,2′,7,7′‐Tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (Spiro‐OMeTAD) HTM. Radiation induces fluorine diffusion from the LiTFSI dopant toward the perovskite absorber (confirmed by depth‐resolved X‐ray photoelectron spectroscopy) introducing defects. Radiation‐induced defects in cells with the TPFB dopant instead are different and can be “annealed out” by thermal vacuum resulting in PCE recovery. This is the first report using thermal admittance spectroscopy and deep‐level transient spectroscopy for defect analyses on proton‐irradiated and thermal‐vacuum‐recovered PSCs. The insights generated are expected to contribute to efforts in developing low‐cost light‐weight solar cells for space applications.

Improving the performance of perovskite solar cells with carbon nanotubes as a hole transport layer

There are several types of organometallic halide perovskite solar cells (OHPSCs), but the carbon-based PSC has the lowest materials/fabrication cost and the longest-term stability, making it the most promising for practical application. In this study, we used multi—walled carbon nanotubes (MWCNTs) as the hole transport layer in the PSC architecture. We experimentally achieved an optimized efficiency of 13.7% for a MWCNTs-based device. Besides, this research describes a simulation-guided optimization process to fabricate high-performance MWCNT-based photovoltaics. We have thoroughly investigated the effect of different parameters, such as the total defect density of the absorber, the thickness of the MWCNTs film, the thickness of the absorber, shunt resistance, series resistance, and temperature, utilizing numerical simulations. By using the thin film photovoltaic program SCAPS-1D, we were able to simulate defect states and interfaces between layers to get as close as possible to a realistic PSC in our simulations and analysis. An optimized PSC of F-doped tin oxide (FTO)/titanium dioxide (TiO2)/MAPbI3/MWCNTs/gold (Au) is designed here with a voltage-open circuit (VOC) of 1.100 V, a short-current density (JSC) of 19.192 mA/cm2, and efficiency of 18.3% with a high fill factor (FF) of 86.62%, which is among the best for carbon-based OHPSCs.

UV-Blocking and Transparent Polydimethylsiloxane Film for Improving Stability of Perovskite Photovoltaics

Long-term stability of high-power conversion efficiency (PCE) against UV degradation is imperative to commercialize organometallic halide perovskite solar cells (PSCs). This degradation problem can be solved by blocking UV light, but it leads to a decrease in the PCE due to the decrease in the total amount of absorbed light in the PSC devices. Here, we propose a facile strategy for this challenging problem by attaching textured and UV-blocking bilayer PDMS films with a gradient refractive index onto the glass of PSC devices. We fabricated a gradient-refractive-indexed PDMS film by adopting a two-layer structure─a pure PDMS layer and a UV blocker (2,2′-dihydroxy-4-methoxy benzophenone)-added PDMS layer. The two-layer structure of PDMS films blocked the UV region (>380 nm) and increased the average transmittance by 1.8% at 600–800 nm due to the gradient refractive index. Additionally, the two-layered PDMS films were surface-textured by pattern replication from chemically etched Si surfaces. Surface texturing improved the average transmittance by 4.11% in the visible region as compared to that for the pure-flat PDMS film. The final PDMS film exhibited blocking of light >380 nm and enhanced absorption in the 400–800 nm region. As a result, MAPbI3 PSCs with a surface-textured bilayer PDMS film showed 0.8% higher PCE than did pristine devices. The PCE of the encapsulated device maintained over 90% of its initial performance after 240 h at 55% relative humidity under outdoor conditions and delivered 87% device performance even with additional UV irradiation after 240 h.

Development for Highly Efficient Organometal Halide Perovskite Solar Cells and Modules

Organometal halide perovskites have captured wide interest as a promising material for light-weight and high-efficiency solar cells. Through recent studies of the organometal halide perovskite solar cells (PSCs), the composition of organometal halide perovskites is recognized as one of the key factors in the improvement of the PCE. In this study, we investigated mixed cation perovskite absorber. Additionally, we successfully constructed monolithic PSC mini-module without I-V hysteresis. In the case of MA-free PSCs, the 24.9% PCE (0.187 cm2) and 21.6% PCE (2.76 cm2 monolithic PSC mini-module) were obtained, respectively. We also developed semitransparent perovskite top cells with higher durability and transmittance for tandem solar cells. The PCEs of 19.5% (certified 19.3%) and 26.2% were achieved for a 1 cm2 semi-transparent perovskite top cell and four-terminal PSC/CIGS tandem solar cells, respectively.

Improvement of a Two-step Method for Highly Efficient Perovskite Solar Cells via Modification of a Metal Halide Template and Dipping Conditions

We report an improved two-step method for the development of highly efficient organometal halide perovskite solar cells (PSCs). The improvement of the two-step method has been achieved with the modification of the metal halide template and the controlling of the dipping solution temperature. With a single cation methylammonium lead iodide PSC fabricated via a modified PbI2 template and the dipping solution temperature of 70 °C, we have accomplished a PCE of 17.14% enhanced from the conventional two-step methods.

Highly flexible organo-metal halide perovskite solar cells based on silver nanowire-polymer hybrid electrodes.

Flexible perovskite solar cells (FPSCs) have attracted considerable attention due to their broad application possibilities in next generation electronics. However, the commonly used transparent conductive electrodes (TCEs), such as indium tin oxide (ITO), suffer from poor flexible performance, impeding the development of FPSCs. Here, we propose a hybrid electrode (PUA/AgNWs/PH1000) comprising a thin percolation network of silver nanowires (AgNWs) inlaid on the surface of a flexible substrate (PUA) modified with a conductive layer (PH1000), which exhibits high optical transmittance and electrical conductivity, as well as robust mechanical flexibility. By applying the proposed PUA/AgNWs/PH1000 hybrid electrode in FPSCs, the resulting ITO-free devices exhibit the desired flexibility and mechanical stability; it can survive repeated continuous bending cycles and retain 77.4% of its initial power conversion efficiency after 10 000 bending cycles with the bending radius of 5 mm.

Optimization of tin based perovskite solar cell employing CuSbS2 as HTL: A numerical simulation approach

The expeditious progresses in the domain of organo-metallic halide perovskite solar cells has resulted in PCE of more than 25.5%. However, their extensive utilization and fully fledged commercialization is currently restricted owing to the existence of expensive hole transport layer (HTL) viz Spiro-OmeTAD in the novel devices. In this paper, a low cost and easily available materials i.e. CuSbS2 and fullerene (C60) are endeavored as HTL and ETL respectively, by utilizing SCAPS 1D simulator, which can also yield high solar cell performance. In this context, the analysis of Spiro-OmeTAD, CuSbS2 as HTLs and TiO2, C60 as ETLs has been validated. In addition, effect of thickness of HTLs on perovskite solar cells using CH3NH3SnI3 as light harvester & C60 as hole inhibiting layer/electron transport layer (ETL) has been also examined. The recommended simulation reveals that using 20 nm of CuSbS2 layer can outperform Spiro-OmeTAD as HTL for cell fabrication. It has been observed that by employing proposed perovskite solar cell configuration FTO/C60/CH3NH3SnI3/CuSbS2/Au, an efficiency (PCE) of 26.05% associated with fill factor (FF) of 82.98%, short circuit current (Jsc) of 31.646 mA/cm2 & open circuit voltage (Voc) of 0.9918 V can be yielded which assures exhibition of better solar cell performance than the existing solar cell.

Four‐Terminal Perovskite/Copper Indium Gallium Selenide Tandem Solar Cells: Unveiling the Path to >27% in Power Conversion Efficiency

Over the past decade, the impressive progress in power conversion efficiency (PCE) of organometallic halide perovskite solar cells (PSCs), coupled with their ready integration into tandem solar cells, has led them to approach PCEs of 30% for tandem solar cells with a silicon bottom subcell. However, the complementary technology of perovskite/copper indium gallium selenide (CIGS) tandem solar cells has been thus far unable to reach similar efficiency values. Herein, a further advance in the efficiency of 4T perovskite/CIGS tandems is demonstrated, increasing the PCE up to 27.3% via systematic optimization of the top semitransparent PSC. Improvements in light management through the optimization of anti‐reflection coatings, coupled with the development of transparent conductive oxides that incur very low parasitic absorption are reported. It is revealed that both are crucial for maximizing efficiency and, by utilizing additional optical simulations, a detailed loss analysis that enables us to outline a path toward approaching 30% PCE for 4T perovskite/CIGS tandem devices is developed.

Performance and stability enhancement of mixed dimensional bilayer inverted perovskite (BA2PbI4/MAPbI3) solar cell using drift-diffusion model

A variety of classic photovoltaic technologies, such as multi-crystal silicon and copper indium gallium selenide, have been exceeded by organometal halide perovskite solar cells, which have made significant advancements in the cost-effective manufacturing method as well as the high power conversion efficiency. Meanwhile, the unfavourable operational stability of perovskite solar cells is impeding the commercialization of the technology. When exposed to critical environmental factors such as rising moisture and intense sunlight, perovskite solar cells suffer lattice degradation and lose their ability to harvest energy. As a result, enhancing the stability of perovskite cells is one of the most important variables in determining the next wave of progress for the technology. While there have been numerous techniques reported to improve the stability of perovskite-based photovoltaic cell, the construction of a more than one dimension (2D/3D) perovskite as the light absorbing layer has recently emerged as one of the most reliable strategies to stabilise the perovskite-based device without compromising photo physical performance. Herein, we have computationally simulated p-i-n device configuration composed of ITO/NiO/2D perovskite/3D perovskite/PCBM/Au. The Ruddlesden-Popper (RP) phases of two-dimensional perovskite act as a cover layer, which inhibits the deterioration of 3D perovskite in an open-air environment. Both optical and electrical simulation is performed using solar cell capacitance simulator (SCAPS). Simulation findings showed that the enhancements in overall performance are due to the decrease in the trap state's density and better coordination of the band between the 2D/3D perovskite and the hole-transporting materials. Effects of the interfacial defects (2D perovskite/HTL and 3D perovskite/ETL) on solar cell parameters are also performed. Simulation results reveal that the defects at 3D perovskite/ETL interfacial are more dominating in overall performance degradation. Parametric differences, such as thickness of various layers, standard solar spectra, further refine the proposed architecture. The multidimensional-based architecture proposed in this work resulted in a power conversion efficiency (PCE) of 19.6%.

(Invited) Tailoring Crystal Morphology and Interfacial Charge Transfer in Perovskite Solar Cells

The past decade has witnessed tremendous advances in organometal halide perovskite solar cells (PSCs) due largely to the stellar set of optoelectronic properties of perovskites such as high absorption coefficient, long carrier diffusion length, and low electron-hole recombination. Notably, organolead halide PSC has reached a certified champion power conversion efficiency (PCE) of 25.5%. In this talk, first, I will discuss a meniscus-assisted solution printing (MASP) strategy to yield large-grained dense perovskite film with good crystallization and preferred orientation. The growth kinetics of perovskite crystals is scrutinized by in-situ optical microscopy tracking to understand the crystallization mechanism. The perovskite film produced by MASP exhibits excellent optoelectronic properties for high-efficiency PSCs. We also MASP cross-aligned conductive nanowires for biodegradable flexible PSCs. Second, I will present a simple yet robust acid-treatment strategy to judiciously create an amorphous TiO2 buffer layer intimately situated on the anatase TiO2 surface as electron transport layer (ETL) for efficient electron transport. The facile acid treatment is capable of weakening the bonding of zigzag octahedral chains in anatase TiO2, thereby shortening staggered octahedron chains to form an amorphous buffer layer on the anatase TiO2 surface. Such amorphous TiO2-coated ETL possesses an increased electron density due to the presence of oxygen vacancies, leading to efficient electron transfer from perovskite to TiO2. Compared to pristine TiO2-based devices, the perovskite solar cells (PSCs) with acid-treated TiO2 ETL exhibit enhanced short circuit current and PCE. Notably, we also tailor carrier dynamics in PSCs via precise dimension and architecture control and interfacial positioning of plasmonic nanoparticles in TiO2 ETL. Third, I will demonstrate synergistic cascade carrier extraction via dual interfacial positioning of ambipolar black phosphorene (BP) for high-efficiency PSCs. Concurrently enhanced carrier extraction at both electron transport layer/perovskite and perovskite/hole transport layer interfaces is achieved through judicious design and position of BP with tailored thickness as dual-functional nanomaterials. Fourth, I will introduce a robust route that simultaneously allows defect passivation and reduced energy difference between perovskite and hole transport layer (HTL) via the judicious placement of polar chlorine-terminated silane molecules at the interface. An integrated experimental and density functional theory study demonstrates that the dipole layer formed by the silane molecules decreases the perovskite work function, imparting an Ohmic character to the perovskite/HTL contact. The corresponding PSCs manifest a nearly 20% increase in PCE over pristine devices and a markedly enhanced device stability. Finally, I will show the spatial poling-initiated perovskite self-healing for defects passivation. The spatial poling significantly enhances the ion migration recovery after removing electric field. Particularly, the ion recovery tends to form a perfect lattice structure, leading to decreased defects in the perovskite layer with enhanced stability.

Composition engineering to enhance the photovoltaic performance and to prolong the lifetime for silver bismuth iodide solar cell

Lead, a toxic element in organometal halide perovskite solar cells, has caught lots of attention and has raised public concerns after such perovskite solar cells made rapid progress in their photovoltaic performance. Herein, a series of lead-free light absorber layers with a rudorffite structure were examined in this study. The obscure role of A-site and B-site cation in silver bismuth iodide rudorffite materials has been revealed through their energy diagrams and surface potential analyses. By manipulating the stoichiometric ratio of bismuth and silver at a ratio of 1.1/3, a Ag3BiI6 layer with uniform morphology, high carrier mobility, and a high light response was obtained. The superior optoelectrical properties of the modified Ag3BiI6 active layer directly influenced the photovoltaic performance and the environmental stability of such a device. The photovoltaic device with the modified Ag3BiI6 active layer exhibited a PCE of 2.60%. It also maintained over 80% of its initial PCE after being stored in an ambient environment for over 3,000 h. This result sheds light on how to process silver bismuth iodide materials and extends the knowledge for rudorffite materials.

Facilitate hole transport with thin 2D perovskite capping layer to passivate interface defects of 3D perovskite solar cells using PEABr

Hybrid 2D/3D-perovskites are attracting more interest in the area of organometal halide perovskite solar cells (PSCs) because of their high efficiency and extended environmental stability. The 3D portion in 2D/3D perovskites, serves as an active material with exceptional optoelectronic characteristics (for example excellent light absorption and an extended carrier lifetime), while its 2D counterpart protects against environmental conditions (water and oxygen) and increase the stability of the whole structure. In this study, a hetero-structure 2D/3D is constructed via spin-coating a phenyl-ethyl ammonium bromide (PEABr) solution upon over of (FA0.6MA0.4)PbI3 3D perovskite films. As compared to their 3D analogs, the PSC devices based on optimized 2D/3D hetero-structures display substantial improvements in photovoltaic efficiency due to the passivation of cationic and halide vacancies on the surface of 3D perovskite for better energy level alignments, longer carrier lifetimes, and fewer defects, which facilitate hole transfer and transport to the hole transport layer and reduce interface recombination centers. The extremely-thin film of 2D perovskite on the top of 3D perovskite boots the stability and reduces the crystal imperfection of 3D perovskite. Furthermore, the PEABr-treated perovskite device has a PCE of 20.57% as compared with the control device, which has a PCE of 17.01%.

Cs incorporation via sequential deposition for stable and scalable organometal halide perovskite solar cells

In this study, uniform Cs distribution in an organometal halide perovskite (OHP) film was achieved via sequential deposition method entailing the dissolution of Cs compounds in dimethyl formamide (DMF) with inorganic components, as opposed to using isopropyl alcohol with organic components, and the thermal stability and crystallinity of the OHP film were enhanced by improving the structural stability through Cs incorporation. Additionally, the device performance and thermal stability of OHP solar cells were enhanced by Cs incorporation, which led to fewer defect sites and the suppression of defect generation in OHP films, as confirmed by optical and electrical analysis, improving the overall film quality. The sequential deposition method was more amenable to scaling up than the anti-solvent assisted one-step spin-casting method, as demonstrated by the sequential deposition of the OHP film uniformly over a substrate with size of 8 cm × 8 cm. The uniformly sequentially deposited OHP film was used to create a large-area 1 cm 2 OHP solar cell, which exhibited a high power conversion efficiency (PCE) of 16.77%. Further scalability of the sequentially deposited OHP solar cell was confirmed by highly uniform device performances by three cells on a single substrate with a negligible PCE standard deviation of 0.94%. • The uniform Cs distribution in OHP film is achieved via sequential deposition. • The thermal stability of the OHP film increased through Cs incorporation. • The performance and stability of the PeSCs is improved. • Uniform OHP film with large size is successfully fabricated by sequential deposition. • A p-i-n PeSCs with a size of 1 cm 2 was successfully fabricated.

Stability enhancement of perovskite solar cells via multi-point ultraviolet-curing-based protection

As efficiency approaches the limit, it becomes more urgent to solve the toxicity and instability of organometal halide perovskite solar cells (PSCs), which asks for enhancement by applying methods that majorly contribute to stability itself to help prevent device from suffering from harmful matters. In this paper, we introduce a simple ultraviolet (UV) curing recipe which contains ethoxylated trimethylolpropane triacrylate (ETPTA) and 2-hydroxy-2-methyl-1-phenyl-1-propanone. ETPTA is polymerized by UV-curing and is applied as additive rather than as encapsulation material to distribute around the perovskite as a cross-linked network. Suitable amount of UV-gel added in perovskite precursor solution and hole transport material solution during device fabrication could promotes the crystallization of perovskite, reduce the diffusion of moisture in hole transport layer and therefore avoid degradation of PSCs. Notable protection happens with a volume percentage of ETPTA no more than 0.5%, especially in ambient conditions with humidity larger than 60%. • UV-gel is introduced through fabrication process and polymerized by UV-curing. • The addition of UV-gel is beneficial to the crystallization of perovskite. • Polymerized UV-gel effectively prevents the degradation of perovskite and device.

Performance evaluation of an all inorganic CsGeI3 based perovskite solar cell by numerical simulation

The rapid advancement of organo-metal halide perovskite solar cells has led to a certified power conversion efficiency (PCE) of >25%. However, their ability to be implemented and commercialized on a large scale is currently limited due to the presence of toxic elements and the costly hole transport material (HTM) in the highly efficient cells. In the present work, a theoretical study on lead-free, environmental-friendly CsGeI3 based solar cell (SC) is demonstrated. Factors influencing the device parameters, such as thickness, doping, and defect concentration, have been thoroughly investigated to better understand material properties. With optimal material properties, the simulation results demonstrated 10.8% optimized PCE, Jsc of 22.08 mAcm−2, Voc of 0.667 V, and FF of 73.49%. These findings open up a new path for CsGeI3 as light-absorbing material to achieve clean, renewable energy.

Bifunctional green cellulose derivatives employed for high efficiency and stable perovskite solar cells under ambient environment

Organometallic halide perovskite solar cells (PSCs) with high efficiency have attracted enormous attention for commercialization. However, the perovskite undergoes rapid degradation in humid condition, leading to serious decline in both device performance and stability. Herein, an extremely cheap, environmentally friendly and nature cellulose derivative with plentiful hydrogen bonds, cellulose acetate (CA), is introduced into perovskite precursor solution to serve as bifunctional green additive. The hydrogen bonding interactions between the perovskite and CA could passivate the defects at the grain boundaries to suppress the non-radiative recombination, improving the open-circuit voltage and power conversion efficiency (PCE) of PSC. Besides, the long polymer chain of CA can eliminate the annealing-induced lattice tensile/compressive strain during the perovskite film fabrication under ambient environment to enhance its stability. As a result, the dense and defect-less morphology of CA-modified perovskite film with large sized grains, passivated grain boundaries and ideal surface coverage is obtained. The optimized PSC achieves an impressive 19.53% PCE and negligible hysteresis of the photocurrent. Moreover, the thermal stability and humidity resistance of CA-modified PSC are both significantly improved. This strategy provides a promising method for advancing the PSCs application and commercialization.