Triple Cation Perovskite Solar Cells Research Articles

Investigation of FABr treatment's potential for triple-cation multi-halide perovskite solar cells

In order to preserve the effectual potential of triple-cation coupled with multi-halide perovskites (PVTs), the phase-related conflict amongst different precursors has to be resolved. There arises the necessity of post-growth passivation treatments, especially using formamidinium bromide (FABr) upon such PVT films. In this research, a methodical comparison assessment is performed on triple-cation, multi-halide (CsFAMAPbIBr)-based PVT solar cells (PSCs) with and without FABr passivation using numerical study. A meticulous estimation of all the performance parameters of both PSCs was implemented in accordance with transformations in thickness, effective density, and acceptor density of the PVT absorber layer together with the charge transport layer thickness variations. The investigation revealed that the charge carrier generation rate remained the same after FABr passivation, however,the recombination rate was lowered by ∼ 32 % (from 7.27 × 1021 to 4.92 × 1021 cm-3s−1). The analysis discerned that at minimum valence band effective density of PVT absorber: 1 × 1017 cm−3, FABr-treated CsFAMAPbIBr-based PSC ensures the highest power conversion efficiency of 24.62 % against its un-passivated correspondent of 22.25 %. Further, this investigation imparts the remarkableness of FABr passivation treatment in regulating the overall performance of triple-cation and multi-halide-based PSCs.

Hysteresis and Its Correlation to Ionic Defects in Perovskite Solar Cells.

Ion migration has been reported to be one of the main reasons for hysteresis in the current-voltage (J-V) characteristics of perovskite solar cells. We investigate the interplay between ionic conduction and hysteresis types by studying Cs0.05(FA0.83MA0.17)0.95Pb(I0.9Br0.1)3 triple-cation perovskite solar cells through a combination of impedance spectroscopy (IS) and sweep-rate-dependent J-V curves. By comparing polycrystalline devices to single-crystal MAPbI3 devices, we separate two defects, β and γ, both originating from long-range ionic conduction in the bulk. Defect β is associated with a dielectric relaxation, while the migration of γ is influenced by the perovskite/hole transport layer interface. These conduction types are the causes of different types of hysteresis in J-V curves. The accumulation of ionic defects at the transport layer is the dominant cause for observing tunnel-diode-like characteristics in the J-V curves. By comparing devices with interface modifications at the electron and hole transport layers, we discuss the species and polarity of involved defects.

Multi-Functional Regulation on Buried Interface for Achieving Efficient Triple-Cation Perovskite Solar Cells.

Mixed-cation perovskite solar cells (PSCs) have attracted much attention because of the advantages of suitable bandgap and stability. It is still a challenge to rationally design and modify the perovskite/tin oxide (SnO2) heterogeneous interface for achieving highly efficient and stable PSCs. Herein, a strategy of one-stone-for-three-birds is proposed to achieve multi-functional interface regulation via introducing N-Chlorosuccinimide (NCS) into the solution of SnO2: i) C═O functional group in NCS can induces strong binding affinity to uncoordinated defects (oxygen vacancies, free lead ions, etc) at the buried interface and passivate them; ii) incomplete in situ hydrolysis reactions can occur spontaneously and adjust the pH value of the SnO2 solution to achieve a more matchable energy level; iii) effectively releasing the residual stress of the underlying perovskite. As a result, a champion power conversion efficiency (PCE) of 24.74% is achieved with a device structure of ITO/SnO2/Perovskite/Spiro-OMeTAD/Ag, which is one of the highest values for cesium-formamidinium-methylammonium (CsFAMA) triple cation PSCs. Furthermore, the device without encapsulation can sustain 94.6% of its initial PCE after the storage at room temperature and relative humidity (RH) of 20% for 40 days. The research provides a versatile way to manipulate buried interface for achieving efficient and stable PSCs.

Green Anisole as Antisolvent in Planar Triple-Cation Perovskite Solar Cells with Varying Cesium Concentrations.

The feasibility of replacing toxic chlorobenzene antisolvents with environmentally friendly anisole in the fabrication of planar triple-cation perovskite solar cells was explored here. The successful integration of anisole not only ensures comparable device performance but also contributes to the development of more sustainable and green fabrication processes for next-generation photovoltaic technologies. Nevertheless, to ensure the possibility of achieving well-functioning unencapsulated devices whose working operation depends on outdoor atmospheric conditions, we found that adjusting the cesium concentrations in the perovskite layers enabled the electrical characterization of efficient devices even under high relative humidity conditions (more than 40%). We found that 10% of CsI in the precursor solution will make devices with low hysteresis indexes and sustained performance stability over a 90-day period both with cholorobenzene and anisole antisolvent. These results further confirm that green anisole can replace chlorobenzene as an antisolvent.

A Lewis-base-based antisolvent method for fabricating triple-cation perovskite solar cells

The incorporation of tetrahydrofuran into ethyl acetate enhances the power conversion efficiency of the perovskite solar cell, primarily due to an elevation in the short-circuit current.

Buried interface modification by multifunctional ionic liquids for triple-cation perovskite solar cells made in a fully ambient air

The diagram of the chemical structure of BMIMPF6 and device structure in this work.

An Alternative to Chlorobenzene as a Hole Transport Materials Solvent for High-Performance Perovskite Solar Cells

Spiro-OMeTAD is a widely used hole-transporting layer (HTL) material, characterized by high hole mobility and good film-forming properties, in perovskite solar cells (PSCs). However, this material has high synthesis costs, low solubility, dependence on hygroscopic dopants, and a low commercial potential. Recently, we investigated alternative materials with good solubility, simple synthetic methods, and good electrical characteristics for use as hole transport materials (HTM) in triple-cation PSCs. Herein, (E,E,E,E)-4,4′,4″,4′″-[Benzene-1,2,4,5-tetrayltetrakis(ethene-2,1-diyl)]tetrakis[N,N-bis(4-methoxyphenyl)aniline], which has a small molecular weight and similar properties to Spiro-OMeTAD, was assessed for use as a HTM via a pre-test of device performance, including its electrical properties, surface morphology, and coating process method, with PSC efficiencies routinely surpassing 20%. A remarkable open-circuit voltage of 1.111, along with a photovoltaic efficiency of 20.18% was obtained in PSCs using this HTM with dichloromethane (DCM) instead of chlorobenzene, indicative of its potential for the fabrication of resistance components with improved surface uniformity. These results provide insights into DCM as an efficient solvent for small molecule-based HTM.

Influence of an Organic Salt-Based Stabilizing Additive on Charge Carrier Dynamics in Triple Cation Perovskite Solar Cells.

Besides further improvement in the power conversion efficiency (PCE) of perovskite solar cells (PSC), their long-term stability must also be ensured. Additives such as organic cations with halide counter anions are considered promising candidates to address this challenge, conferring both higher performance and increased stability to perovskite-based devices. Here, a stabilizing additive (N,N-dimethylmethyleneiminium chloride, [Dmmim]Cl) is identified, and its effect on charge carrier mobility and lifetime under thermal stress in triple cation perovskite (Cs0.05 MA0.05 FA0.90 PbI3 ) thin films is investigated. To explore the fundamental mechanisms limiting charge carrier mobility, temperature-dependent microwave conductivity measurements are performed. Different mobility behaviors across two temperature regions are revealed, following the power law Tm , indicating two different dominant scattering mechanisms. The low-temperature region is assigned to charge carrier scattering with polar optical phonons, while a strong decrease in mobility at high temperatures is due to dynamic disorder. The results obtained rationalize the improved stability of the [Dmmim]Cl-doped films and devices compared to the undoped reference samples, by limiting temperature-activated mobile ions and retarding degradation of the perovskite film.

Ionic Mobility and Charge Carriers Recombination Analyzed in Triple Cation Perovskite Solar Cells

In this work, a study of a characterization technique based on open circuit voltage decay is carried out to obtain the recombination resistance of mobile charge carriers and ionic migration in triple cation perovskite solar cells. The devices were fabricated with the structure FTO/TiO2/Cs0.05FA1−XMAXPb(I1−XBrX)3/spiroOMetad/Au. An equivalent circuit, created in Ngspice, was developed adjusting the capacitance and resistance values to fit the experimental open circuit voltage (Voc) decay curves observed. The aim of this study is to associate the perovskite ionic migration with the Voc characteristic time of charge transport in triple cation perovskite solar cells. Thus, an analysis of the open circuit voltage transient behavior was made by taking measurements of the photovoltage as a function of time. The results indicate that the technique shows charge recombination while the device is illuminated. In addition, an enhancement of the recombination resistance when increasing the FA+ concentration was observed. Finally, the transient behavior was associated with MA+, FA+, Cs+ and I− migration, obtaining an ionic mobility in the range between 10−10 to 10−12 cm2 (Vs)−1.

Accelerated constant current stress on triple cation perovskite solar cells

The increasing demand for renewable and cost-effective energy sources requires not only the development of alternative solar technologies, but these new technologies must be stable enough to be used in a real-life application. For this reason, perovskite solar cells (PSCs) must be investigated not only in terms of power conversion efficiency, but also in terms of reliability. In this work, accelerated forward current stress is applied as a tool to investigate PSCs stability and degradation kinetic emulating real-life scenarios. The choice of the hole-blocking layer (HBL) plays a crucial role in PSCs intrinsic instability as well as in their degradation rate, which follows a stretched exponential law. Here, tin oxide (SnOX) and bathocuproine (BCP) are investigated as HBLs observing that for low stress currents BCP-based PSCs degrade faster than SnOX-based PSCs, whereas for large stress currents SnOX-based PSCs degrade faster than BCP-based PSCs. The results also indicated that the major cause of degradation in the devices is primarily driven by the formation of shunt paths leading to cell breakdown. Our findings offer valuable insights for improving the stability of PSCs under accelerated stress conditions and provide useful information for the design of PSC-based solar panels depending on their field of applications.

Humidifying, heating and trap-density effects on triple-cation perovskite solar cells

The effect of moisture and heat are important challenges in perovskite solar cells (PSCs). Herein we studied the performance of triple-cation PSCs in different operating environmental conditions. Humidified cells exhibited a hopeful character by increasing the open-circuit voltage (VOC) and short-circuit current density (JSC) to 940 mV and 22.85 mA cm−2 with a power conversion efficiency (PCE) of 14.34%. In addition, further analyses showed that hysteresis index and charge transfer resistance decrease down to 0.4% and 1.67 kΩ. The origin of superior stability is ion segregation to the interface, which removes the antisite defect states. Finally, the effect of operating temperature and trap density on structure and performance was also studied systematically.

Enhanced Hole Mobility of p-Type Materials by Molecular Engineering for Efficient Perovskite Solar Cells.

Star-shaped triazatruxene derivative hole-transporting materials (HTMs), namely, 3,8,13-tris(4-(8a,9a-dihydro-9H-carbazol-9-yl)phenyl)-5,10,15-trihexyl-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole (TAT-TY1) and 3,8,13-tris(4-(8a,9a-dihydro-9H-carbazol-9-yl)phenyl)-5,10,15-trihexyl-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole (TAT-TY2), containing electron-rich triazatruxene cores and donor carbazole moieties, were synthesized and successfully used in triple-cation perovskite solar cells. All the HTMs were obtained from relatively inexpensive precursor materials using well-known synthesis procedures and uncomplicated purification steps. All the HTMs, including the 5,10,15-trihexyl-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole (TAT-H) main core, had suitable highest occupied molecular orbitals (HOMOs) for perovskite (TAT-H: -5.15 eV, TAT-TY1: -5.17 eV, and TAT-TY2: -5.2 eV). Steady-state and time-resolved photoluminescence results revealed that hole transport from the valence band of the perovskite into the HOMO of the new triazatruxene derivatives was more efficient than with TAT-H. Furthermore, the substitution of n-hexylcarbazole and 9-phenylcarbazole in triazatruxene altered the crystalline nature of the main core, resulting in a smooth and pinhole-free thin-film morphology. As a result, the hole mobilities of TAT-TY1 and TAT-TY2 were measured to be one order of magnitude higher than that of TAT-H. Finally, TAT-TY1 and TAT-TY2 achieved power conversion efficiencies of up to 17.5 and 16.3%, respectively, compared to the reference Spiro-OMeTAD. These results demonstrate that the new star-shaped triazatruxene derivative HTMs can be synthesized without using complicated synthesis strategies by controlling the intrinsic morphology of the TAT-H main core.

Graphene oxide incorporation in Ag-doped ZnO nanocomposite as efficient electron extraction material for planar perovskite solar cells

The hybrid metal halide perovskite solar cells have emerged as potential contenders in the photovoltaic market owing to their exceptional optoelectronic properties. Zinc oxide (ZnO) is a reasonable option for an electron extraction layer (EEL) in perovskite solar cells due to its wide band gap, energy band alignment with the absorber layer, and ease of production. Spincoating suspensions of ZnO nanocomposites EELs at lower temperatures (110 °C) employed in regular planar triple cation perovskite solar cells. The impact of Ag doping and GO incorporation in ZnO was studied in detail to get insights into the photovoltaic performance of PSC. Due to the inclusion of GO and Ag in ZnO, a significant enhancement in photovoltaic performance was observed and the target GO-Ag-ZnO EEL-based PSC exhibited PCE of 8.72 % which was found almost 16 % higher than pristine ZnO EEL-based PSC. We attribute the enhanced photovoltaic performance to the superior electron transport/extraction facilitated by the inclusion of graphene layers. This improvement can also be linked to the superior quality of the perovskite thin film employed in the study.

Low-temperature processed natural hematite as an electron extraction layer for efficient and stable perovskite solar cells

The mixed halide perovskite solar cells (PSC) have manifested as a contender to market-dominating silicon counterparts owing to their low-temperature solution processing and high efficiency. In PSCs, the electron extraction layer (EEL) plays a vital role as it controls charge transport/extraction from the perovskite absorber layer to the EEL and also determines interfacial recombination and charge accumulation at the EEL/perovskite interface. In this work, high-purity natural hematite (α-Fe2O3) is reported for the first time as the EEL in triple-cation perovskite (CsFAMA) solar cells. To show the cost-effectiveness of this novel EEL, the entire device fabrication process was carried out at a temperature below 150 °C. The optimal α-Fe2O3 EEL shows a mobility value of 9.5 × 10−4 cm−2 V−1 s−1 and trap densities of around 2.40 × 1016 cm−3; the latter is close to state-of-the-art SnO2 EEL (1.26 × 1016 cm−3). The PSCs employing optimal EEL concentration of 10 mg/mL demonstrated a power conversion efficiency (PCE) of 13.3 %, fill factor of 68 %, and VOC of 1.03 V. X-ray diffraction studies show a high crystallinity of natural hematite whereas the photoluminescence studies show a fast carrier extraction from the perovskite to the EEL. The natural α-Fe2O3-based PSCs exhibited superior shelf-life stability of over 30 days due to less charge recombination and smoother CsFAMA thin film deposited over α-Fe2O3 EEL. The low-temperature processed natural α-Fe2O3 EEL can therefore be a promising EEL material for low-cost efficient PSCs.

Moderate temperature deposition of RF magnetron sputtered SnO2-based electron transporting layer for triple cation perovskite solar cells

The perovskite solar cells (PSCs) are still facing the two main challenges of stability and scalability to meet the requirements for their potential commercialization. Therefore, developing a uniform, efficient, high quality and cost-effective electron transport layer (ETL) thin film to achieve a stable PSC is one of the key factors to address these main issues. Magnetron sputtering deposition has been widely used for its high quality thin film deposition as well as its ability to deposit films uniformly on large area at the industrial scale. In this work, we report on the composition, structural, chemical state, and electronic properties of moderate temperature radio frequency (RF) sputtered SnO2. Ar and O2 are employed as plasma-sputtering and reactive gases, respectively. We demonstrate the possibility to grow a high quality and stable SnO2 thin films with high transport properties by reactive RF magnetron sputtering. Our findings show that PSC devices based on the sputtered SnO2 ETL have reached a power conversion efficiency up to 17.10% and an average operational lifetime over 200 h. These uniform sputtered SnO2 thin films with improved characteristics are promising for large photovoltaic modules and advanced optoelectronic devices.

Poly(3-dodecylthiophene)-grafted multi-walled carbon nanotubes: an additive for improving charge transport properties of triple cation perovskite solar cells

Poly(3-dodecylthiophene)-grafted multi-walled carbon nanotubes: an additive for improving charge transport properties of triple cation perovskite solar cells

Efficient planar mixed-cation perovskite photovoltaics with low-temperature-processed indium sulfide as electron transport material

Electron transport materials(ETMs) are crucial for efficient transport of photocarriers from the perovskites to the cathode in perovskite solar cells (PSCs). Although titanium dioxide (TiO2) is frequently employed as an ETM, PSC performance and applicability are hindered by its high-temperature manufacturing and limited electron mobility. In this work, a low-temperature solution-processable indium sulfide (In2S3) was incorporated into triple-cation perovskite solar cells to be an efficient ETM for the first time. After solvent-thermal synthesis of In2S3, followed by spin-coatingpreparation of In2S3 ETM, aPSC is constructed. The photoelectrical measurements show that the In2S3-based PSC has lower density of charge traps, higher conductivity, better electron transportation at the In2S3/perovskite interfaces, and a lower transfer resistance and carrier recombination. The PSC-based In2S3 yields a champion efficiency of 18.182%, and the PSC-based TiO2 gets an efficiency of 15.288%. Without encapsulation, the In2S3-based devices demonstrate increased stability in ambient environments. Our ETM layer and perovskite were made at low temperatures, which may open up new possibilities for solution-processed flexible electronics.

The role of hydrophobic molecules in the optoelectronical attributes of triple-cation perovskite solar cells

The partial modification of perovskite cations has already been done to stabilize perovskite solar cells (PSCs). In this study, Cs/FA/MA triple-cation (3D) perovskite and PTA2PbI4 (2D)/3D perovskite were used as light-absorbing materials in PSCs. Phenyl trimethylammonium iodide (PTAI) was also used as a passivator. It was found that PTAI can serve as an original PTA two-dimensional (2D) cation and as a basis for the formation of 2D/3D heterostructure films. Since an improper post-annealing temperature leads to the uncontrollable degradation of 3D perovskites, this study examines post-annealing at various temperatures to make a 2D perovskite film on a 3D perovskite layer. The proper post-annealing temperature to make a 2D/3D structure was 150 °C exerted for five minutes. Through PTAI post-treatment in these optimum conditions, the morphology of the perovskite layer was improved, which confirms the facilitation of the charge transfer. Indeed, a 2D/3D heterostructure originating from a PTAI solution serves as a film to protect perovskite layer from destruction and improves charge transfer. Therefore, the treatment of perovskite layers, as practiced in this study, can enhances the stability and the efficiency of hole-transport-free PSCs and predispose their industrial production. The efficiency of the optimized device was enhanced for 35 % in comparison to the control samples. The device could also maintain 90 % of its PCE for 177 days.

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.

A novel parameter identification strategy based on COOT optimizer applied to a three-diode model of triple cation perovskite solar cells

A novel parameter identification strategy based on COOT optimizer applied to a three-diode model of triple cation perovskite solar cells