MAPbI3 Perovskite Research Articles

Improving the Efficiency and Stability of MAPbI3 Perovskite Solar Cells by Dipeptide Molecules.

Passivating the electronic defects of metal halide perovskite is regarded as an effective way to improve the power conversion efficiency (PCE) of perovskite solar cells (PVSCs). Here, a series of dipeptide molecules with abundant ─C═O, ─O─ and ─NH functional groups as defects passivators for perovskite films are employed. These dipeptide molecules are utilized to treat the surface of prototype methyl ammonium lead iodide (MAPbI3) films and the corresponding PVSCs exhibit enhanced photovoltaic performance and ambient stability, which can be ascribed to: 1) the ─C═O and ─O─ can interact with the undercoordinated Pb2+ ions and the ─NH groups can form hydrogen bonds with the I- ions, passivating the defects in perovskite film and reducing charge recombination in PVSCs; 2) the long alkyl chain of dipeptide molecules increases the hydrophobicity of the perovskite surface and thus enhance the stability of PVSCs. The passivated MAPbI3-based PVSCs exhibit a champion PCE of 20.3% and retain 60% of the initial PCE after 1000h. It is believed that the defects passivation engineering using polypeptide moleculars can be applied in other perovskite compositions for high device efficiency and stability.

Surface p-type band bending and energy level alignment minimizes voltage loss in perovskite solar cells

Due to the significant energy level mismatch and contact energy loss between the perovskite absorber layer and p-type hole-transporting layer (HTL), there exists a large hole transport barrier between the perovskite absorber layer and HTL, which hinders hole transport and leads to lower open circuit voltage (VOC) in perovskite devices. Therefore, the surface contact process between the perovskite film and the hole-transporting layer becomes particularly important. Here, we doped cesium silver bismuth bromide (Cs2AgBiBr6) quantum dots (QDs) into ethyl acetate (EA) as an anti-solvent to achieve the formation of a bulk heterojunction structure with quantum dot solution on the surface of the MAPbI3 perovskite film. The perovskite film exhibits appropriate band edge bending and forms a p-type semiconductor. This facilitates the directed transport of photo-induced charge carriers to the hole-transporting layer, reducing carrier recombination losses and enhancing the collection efficiency of holes by the HTL. Through characterization experiments, we have found that this method significantly improves the VOC and photovoltaic conversion efficiency (PCE) of perovskite solar cells. The perovskite solar cells fabricated using this method show a better PCE with a VOC of 1.06 V.

Photo‐catalytic Performance of MAPbI3/g‐C3N4 for Efficient Hydrogen Production under Visible Light

AbstractRecently, hydrogen (H2) production via photocatalytic process has been received enormous attention of the scientific community globally. Perovskite materials such as methyl ammonium lead iodide (MAPbI3) has excellent photovoltaic and photocatalytic properties and may be a promising photocatalyst for H2 production reaction. In this paper, we have designed and synthesized MAPbI3 perovskite embedded graphitic carbon nitride (MAPbI3@g‐C3N4) composite via benign approaches. The phase and crystalline nature was authenticated by powder X‐ray diffractometer. Morphological characteristics of the MAPbI3@g‐C3N4 composite was further checked by scanning electron microscope. The elemental composition and valence states of the MAPbI3@g‐C3N4 was determined by X‐ray photoelectron spectroscopy (XPS). Furthermore, MAPbI3@g‐C3N4 has been explored as photocatalyst for H2 production reaction using hypophosphorous acid (H3PO2) as stabilizing agent. Platinum (Pt) has been used as co‐catalyst. The reasonably good amount of H2 of 21.25 μmol/g was produced using MAPbI3 as photocatalyst. Further, improved H2 amount of 939.4 μmol/g was produced using MAPbI3@g‐C3N4. The MAPbI3@g‐C3N4 exhibited decent H2 production rate of 93.94 μmol/h/g. The excellent stability of the MAPbI3@g‐C3N4 offers its potential applications for reusable studies. This work proposed the potential application of MAPbI3@g‐C3N4 towards H2 generation applications.

Rashba and Dresselhaus effects in doped methylammonium lead halide perovskite MAPbI3.

Inorganic-organic lead halide perovskites, particularly methylammonium lead halide (MAPbI3) perovskite, have been regarded as promising materials for optoelectronics and spintronics. However, the practical applications of these perovskites are limited by lead toxicity and instability under air and pressure. This study investigates the substitution of Pb with Sn and Ge in cubic MAPbI3 perovskite. The properties of the resulting hybrid perovskites are compared using state-of-the-art first-principles-based methodologies, viz., density functional theory (DFT) with generalized gradient approximation (PBE) and hybrid functional (HSE06), in conjunction with spin-orbit coupling (SOC). Here, we mainly study the Rashba-Dresselhaus (RD) effect, which arises due to two major mechanisms: (i) the breaking of inversion symmetry (static and dynamic) and (ii) SOC, originating from the presence of heavy elements. We find significant spin-splitting effects in the conduction band minimum and valence band maximum for hybrid perovskites. To gain a deeper understanding of the observed spin-splitting, the spin textures are analyzed, and Rashba coefficients are calculated. We find that the Dresselhaus effect comes into play in substituted hybrid structures in addition to the usual Rashba effect observed in the pristine compound. Additionally, we observe that the strength of Rashba spin-splitting is substantially tuned by the application of uniaxial strain (±5%). Moreover, certain hybrid perovskites exhibit mechanical stability and ductility, making them potential candidates in perovskite-based optoelectronics and spintronics applications.

Reducing hot carrier cooling rate in metal halide perovskites through lead vacancies: time-domain ab initio analysis

Pb vacancies slow down hot carrier cooling dynamics in MAPbI3 perovskites by introducing intraband states that can trap holes and by decreasing the deformation of the [PbI6]4− octahedron, which leads to weakened electron–phonon coupling.

Surface ligand manipulation enables ∼15% efficient MAPbI3 perovskite quantum dot solar cells.

We reported a surface ligand manipulation strategy for hybrid MAPbI3 perovskite quantum dots (PeQDs) using methylamine iodide (MAI), methylamine thiocyanate (MASCN) and methylamine acetate (MAAc) salts. After MAI salt post-treatment, a record high efficiency of 14.98% was obtained for MAPbI3 PeQD solar cells together with enhanced ambient stability.

Enhancing perovskite solar cell performance through PbI2 in situ passivation using a one-step process: experimental insights and simulations.

The in situ passivation of a methylammonium lead triiodide (MAPbI3) phase spin-coated via a one-step process was experimentally investigated to elucidate their fundamental properties. Structural analysis revealed that MAPbI3 adopts a tetragonal crystal structure with a small excess of PbI2 (0.03 M) segregating at grain boundaries. Optical characterization indicated a band gap of 1.53 eV, highlighting the material's potential as an effective visible light absorber. To facilitate the fabrication of efficient perovskite solar cells (PSCs), we employed a primary n-i-p planar structure (ITO/SnO2/MAPbI3/spiro-OMeTAD/Au) in drift-diffusion SCAPS-1D simulations using experimental data from MAPbI3 layers containing excess PbI2. The simulations predicted a high power conversion efficiency (PCE) of approximately 24%. We further analyzed the impact of series resistance, shunt resistance, MAPbI3 thickness, defect density, as well as radiative and Auger recombination on photovoltaic performance, aiming to identify optimal parameters for enhanced device efficiency. Additionally, the use of ohmic contacts with AZO and IZO as the front and rear contacts, respectively, in the optimized device structure (AZO/SnO2/MAPbI3/spiro-OMeTAD/IZO) resulted in a PCE of 26.03%. These findings provide valuable insights for future research aimed at achieving high-efficiency bifacial MAPbI3 perovskite solar cells.

An intrinsic electrical conductivity study of perovskite powders MAPbX3 (X = I, Br, Cl) to investigate its effect on their photovoltaic performance.

An investigation into the intrinsic electrical conductivity of perovskite powders MAPbX3, where X represents iodine (I), bromine (Br), or chlorine (Cl), was conducted to explore its impact on their photovoltaic performance. Results revealed that MAPbCl3 demonstrated light absorption ability in the ultraviolet and visible regions, while MAPbBr3 showed capacity for light absorption at longer wavelengths in the visible spectrum. On the other hand, MAPbI3 exhibited good absorption at longer wavelengths, indicating its ability to absorb light in the near-infrared region. The optical bandgap of each perovskite was determined to be 2.90 eV for MAPbCl3, 2.20 eV for MAPbBr3, and 1.47 eV for MAPbI3. The electrical conductivities of these powders were measured in-plane using the four-probe method and through-plane by electrochemical impedance spectroscopy (EIS). Electrochemical impedance spectroscopy (EIS) studies revealed a significant change in the conductivity of the MAPbI3 perovskite at temperatures between 80 °C and 100 °C. This change could be attributed to structural modifications induced when the temperature exceeds these values. The through-plane conductivity changed from 3 × 10-8 S cm-1 at 60 °C to approximately 6 × 10-5 S cm-1 at 120 °C and around 2 × 10-3 S cm-1 at 200 °C. Meanwhile, the sheet conductivity (in-plane conductivity) measurements performed at ambient temperature reveal that sheet conductivities are 489 × 103 S m-1, 486 × 103 S m-1 and 510 × 103 S m-1 for MAPbBr3, MAPbCl3 and MAPbI3, respectively. This study provides valuable insights for optimizing the performance of perovskite solar cells. Understanding how dopants influence the electrical conductivity and photovoltaic properties of the perovskite material, this work will enable researchers to design and engineer more efficient and stable solar cell devices based on MAPbX3 perovskites.

Development of MAPbI3.H2O and MAPbI3 perovskite solar cells using TiO2 and P3HT as charge transport layers

Development of MAPbI3.H2O and MAPbI3 perovskite solar cells using TiO2 and P3HT as charge transport layers

(Invited) Development of Perovskite Photovoltaic Devices Using Electrodeposition

Photovoltaic energy is considered today as the most useful natural energy source. To date, different types of solar technologies are industrially available, and the attempts in research and development to improve their potential are continuing. While a number of different materials with different efficiencies can achieve photovoltaic solar energy conversion, so far, no particular material or combination is cheap enough to compete with large-scale fossil fuel-generated electricity. Nowadays, Si-based cells are the most marketed, and they produce high solar conversion efficiencies. However, expensive high temperature and high vacuum processes are adopted in order to elaborate pure Si. Another active material, called perovskite, newly emerged in the solar community. It has attracted major attention worldwide because of its outstanding photovoltaic performance, easy fabrication process, adaptable band-gap, high extinction coefficient, and high carrier mobility. As perovskite is capable of generating a power conversion efficiency approaching that of the leading silicon and that the solar devices fabrication cost is lower, perovskite solar cells tend to be considered as the future of the photovoltaic technology.However, the most used method to deposit perovskite active layer is spin coating, which presents many constraints such as limited surface coverage, non-homogeneity, undefined perovskite crystallinity, and poor stability. Perovskite obtained by spin-coating requires working in inert environment (glove box) and adding some toxic additives to maintain the stability of the perovskite. This increases its cost and enables the deposition only on small surfaces. There is thus a need to look up for alternative deposition methods, more ecofriendly, at lower costs, applicable for large-scale production of perovskite solar cells.Electrodeposition recently started to be explored as an efficient alternative for perovskite fabrication. There have been several attempts over the past years to optimize the electrodeposited perovskite layer and adjust its crystallization on dissimilar layers. All sub-techniques started by electrodepositing an initial layer (PbO, PbO2 or PbI2) followed by one or several conversions of the as-deposited layer. In the presented work, we were able to develop different types of perovskites using electrodeposition, understand the impact of the different deposition parameters on their structure, and improve their stability comparing to the spin-coated ones. Along with the simple MAPbI3 perovskite, the electrodeposition of mixed MAPbI3-xClx and MA1-yFAyPbI3-xBrx perovskites will be presented. The present study is one of its kind, since these mixed perovskite were never developed using electrodeposition before. It was observed that using electrodeposition afford enhanced stability compared to spin-coating process, and the different fabricated perovskites were also proved to experience a positive maturation phenomenon during their first 500 hours of life.The electrodeposition process is easy to manipulate, and the electrodeposited films could grow on surfaces as large as desired, inside an electrolyte, allowing its application in ambient atmosphere, with no need of a glove box. It is also eco-friendly in terms of solvent engineering, since no toxic solvents are needed to stabilize or enhance the morphology of the obtained films. The main solvents used are deionized water, ethanol and isopropanol.

Thermal evaporated PbI2 enables high-quality perovskite films and improves their solar cell performance

The quality of the light-absorbing perovskite layer is essential for fabricating highly efficient and stable perovskite solar cells (PSCs). The utilization of vacuum-deposited PbI2, instead of spin-coated PbI2, significantly enhanced the quality of the perovskite film in a two-step deposition process. A uniform and agglomeration-free formation of the PbI2 layer achieved through the vacuum-deposition method promoted the efficient intercalation of MAI and led to the formation of a high-quality MAPbI3 perovskite layer with enhanced optical properties and surface morphology. Through electrochemical impedance spectroscopy, we discovered that PSCs with vacuum-deposited PbI2 demonstrate suppressed ion migration compared to devices with spin-coated PbI2. With the application of vacuum-deposited PbI2, the power conversion efficiency (PCE) of the device is superior to devices using spin-coated PbI2. Moreover, after a 40 h thermal stability test, the device with vacuum-deposited PbI2 maintained a PCE of over 50% of its initial efficiency, while the PSC with spin-coated PbI2 dropped to 10%.

Cation Dynamics as Structure Explorer in Hybrid Perovskites-The Case of MAPbI3.

Hybrid organic-inorganic perovskites exhibit remarkable potential as cost-effective and high-efficiency materials for photovoltaic applications. Their exceptional chemical tunability opens further routes for optimizing their optical and electronic properties through structural engineering. Nevertheless, the extraordinary softness of the lattice, stemming from its interconnected organic-inorganic composition, unveils formidable challenges in structural characterization. Here, by focusing on the quintessential methylammonium lead triiodide, MAPbI3, we combine first-principles modeling with high-resolution neutron scattering data to identify the key stationary points on its shallow potential energy landscape. This combined experimental and computational approach enables us to benchmark the performance of a collection of semilocal exchange-correlation functionals and to track the local distortions of the perovskite framework, hallmarked by the inelastic neutron scattering response of the organic cation. By conducting a thorough examination of structural distortions, we introduce the IKUR-PVP-1 structural data set. This data set contains nine mechanically stable structural models, each manifesting a distinct vibrational response. IKUR-PVP-1 constitutes a valuable resource for assessing thermal behavior in the low-temperature perovskite phase. In addition, it paves the way for the development of accurate force fields, enabling a comprehensive understanding of the interplay between the structure and dynamics in MAPbI3 and related hybrid perovskites.

PMMA interlayers prepared with various solvents and their effects on the thermal stability of ambient air-processed MAPbI3 perovskite films

Poly(methyl methacrylate) (PMMA) can be used as a charge tunneling interlayer or as an encapsulating layer in perovskite solar cells (PSCs). Its incorporation into the PSCs can enhance the hysteresis behavior, performance, and operational stability of the device. This work shows that the choice of solvents to prepare PMMA interlayers on the ambient air-prepared methylammonium lead iodide (MAPbI3) films can significantly affect the thermal stability of MAPbI3 films. The solvents used were chlorobenzene (CB), ethyl acetate (EA), (1-methoxy-2-propyl) acetate (PGMEA), and CB with 6 vol% isopropanol (IPA) (CB/IPA). Their corresponding PMMA interlayers are designated as CB-PMMA, EA-PMMA, PGMEA-PMMA, and CB/IPA-PMMA, respectively. The CB-PMMA interlayers had the least thermal stability enhancement effect on the MAPbI3 films, as the films suffered severe thermal degradation after annealing at 150 °C for 9 h. In contrast, the EA-PMMA, PGMEA-PMMA, and CB/IPA-PMMA interlayers effectively enhanced the thermal stability of the MAPbI3 films, with only mild thermal degradation observed after the same annealing process. This significant thermal stability enhancement behavior is attributed to the ability of the solvents to extract moisture from the MAPbI3 films during the PMMA spin coating process, thus preventing the entrapped moisture from accelerating the thermal degradation of MAPbI3 films. Therefore, the choice of solvents for PMMA plays a crucial role in enhancing the thermal stability of the MAPbI3 films.

Controlling the grain formation process with oleylamine and 4-dimethylaminopyridine additives for efficient and stable MAPbI3 solar cells

MAPbI3-based perovskite solar cells (PSC) prepared on one-dimensional structured electron transport layers (ETL) have been widely investigated due to excellent photovoltaic properties. However, they have displayed lower stability and power conversion efficiencies compared to other perovskite solar cells such as FAPbI3 and mixed halide perovskites. To improve the quality of perovskite film, we treat MAPbI3 perovskite layer with oleylamine (OAm) and 4-dimethylaminopyridine (DMAP) during preparation. Modified MAPbI3 layers are prepared by spin coating OAm-added precursor solution on ETLs and the DMAP solution is dripped on the rotating substrate during spin coating process. The OAm additive not only enhances significantly the perovskite crystallinity but also reduces the number of pin-holes inside perovskite thin films. The drip starting time of DMAP solution strongly affects the nanostructures of perovskite layer and the PSC performances. The best efficiency of PSC in this study is 20.49 % and is the highest cell performance compared to other MAPbI3-based PSCs using TiO2 nanorod thin films as ETLs in literature. The remarkable enhancement of PSC performance is assigned to the synergetic effects of both DMAP and OAm at the grain boundaries of MAPbI3 layer. Furthermore, the use of OAm and DMAP leads to significant enhancement of device's stability under ambient conditions.

Exploring the impact of kesterite charge transport layers on the photovoltaic properties of MAPbI3 perovskite solar cells

The pressing need for highly efficient renewable energy technologies has propelled research into perovskite solar cells (PSC) due to their excellent photovoltaic properties and high-performance potentials. This research investigates the performance and optimization of MAPbI3-based PSC, focusing on the use of different kesterite based hole transport layers (HTLs). Through a detailed analysis using SCAPs simulation software, the study explores the effects of charge transport layers, thickness, doping, defects, work function, and temperature on the solar cell’s performance, quantum efficiency, energy band alignment, absorption, electric field and recombination. The PSC design parameters were optimized to their highest potential. The best performance was demonstrated by ZnSe/MAPbI3/CBTS with PCE 21.01%. The research provides valuable insights into achieving highly efficient and stable photovoltaic technologies, contributing to the advancement of next-generation perovskite solar cells.

Preliminary exploration of the influence of N+/NHx+ ions/groups bombardment at TiO2 ETLs on performance of MAPbI3 perovskite solar cells

The service stability of organic–inorganic hybrid metal halide perovskite solar cells (PSCs) is one of most important factors, which is seriously influenced by the decomposition of perovskite layer. Especially, the decomposition of perovskite layer could deteriorate the interface between perovskite layer and TiO2 electron transport layer (ETL). In this work, TiO2 ETLs are prepared by the sputtering technique and traditional spin-coating technique. Then, TiO2 ETLs are bombarded by N+/NHx+ ions/groups. PSCs with all TiO2 ETLs are prepared and measured. The results show that after bombardment, N+/NHx+ ions/groups could chemically react with Ti/O ions at surface of TiO2 ETLs. As a result, the conduction band minimum and transfer resistance of TiO2 ETLs both deteriorate, which decrease the power conversion efficiency of PSCs seriously. While, because anatase TiO2 (001) crystal face consists of saturated O/Ti ions and displays the highest surface free energy, TiO2 ETLs with anatase (001) preferred orientation displays the optimal restraint on deterioration of power conversion efficiency caused by N+/NHx+ ions/groups bombardment. Based on above results, TiO2 ETLs with anatase (001) preferred orientation should be the optimal one for PSCs, which could improve the service stability obviously.

Perovskite MAPbI3 preparation by using deep eutectic solvents (DES) based on acetamide

AbstractIn this work, we replaced the conventional solvents such as dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) by deep eutectic solvents (DES) in the synthesis of methylammonium lead iodide perovskite (MAPbI3). The first DES system was based on the combination of acetamide and urea (A–U–P system), the homogenous solution was formed at relative low temperature (~40°C). For the second system which was based on acetamide and choline chloride (A–C–P system), lead nitrate only dissolved at higher temperature (~100°C). Interestingly, lead nitrate did not precipitate when cooling down the solutions to room temperature for both systems, instead they existed as homogenous gel–like mixtures. From these lead precursors, the MAPbI3 have been formed successfully on the glass substrates by two‐step synthesis method. X‐rays diffraction showed that MAPbI3 existed in three different phases such as Tetragonal, Cubic and Orthorhombic. Scanning electron microscope (SEM) results indicated that the perovskite films formed from both systems possessed high quality with large grain size, few grain boundaries and few pin–holes. The results expressed the possibility in using DES for preparing perovskite MAPbI3 thin films which are ready for applications such as solar cells, resistive random‐access memory.

Improving the optoelectrical properties of humid stable, hexamined perovskite lattice by phenetylammonium cation additive

The addition of additives into the perovskite system to increase humid stability can reduce the crystallinity and deteriorate the optoelectrical properties of the perovskite. Here, we modify the crystallinity properties of hexamined MAPbI3 perovskite, a humid-resistant perovskite, by adding penethylammonium iodide (PEAI) molecules to the perovskite system. XRD analysis result suggests that the PEAI causes a significant contraction in perovskite's lattice, which in turn could reconfigures the electronics structure of the perovskite. We found that PEAI succeeded in increasing the grain size from 120 ± 15 nm in pristine perovskite to 180 ± 20 nm in optimum sample (PEAI 1.0) and the compactness of the grain of the film, reducing the trap density from 2.98 × 1022/cm3 in pristine sample to 1.13 × 1022/cm3 in optimum sample, and thereby enabling enhanced carrier dynamics at the interface and the bulk structure of the device. We found that the perovskite solar cells device fabricated using this new perovskite system can produce power conversion efficiency as high as 15.75%, which is an increase of as high as 55% than the control device. These findings may become a potential alternative to improve the optoelectrical properties of the perovskite materials.

Comparative Properties Investigations of Organic Doped Hybrid-Perovskite Solar Cells

The intermediate-dimensional hybrid mixed-organic perovskite active layers PEA2(CH3NH3) n −1(PbI2) n and Dodec2(CH3NH3) n −1(PbI2) n with various n values were successfully fabricated. Their characteristics were compared to find out a promising candidate for solar cell applications. The appropriate layer thickness of the films was tuned by a variation of n values based on stoichiometry. The physical appearance, crystal structure, surface morphology, chemical bonding, optical properties, stability to the heat and humidity, and power conversion efficiency of all films were examined thoroughly to determine their potential. For low n values of both film types, they showed the quasi-2D characteristic improving the film stability and conversion efficiency. The absorption edge of both types of materials shifted to a higher energy side and the electronic band gap increased with the decrease of n values. The mixed phase and MAPbI3 perovskite diffraction peaks were still observable even after time has passed for 72 h. Under the 60% humidity condition, the PEA-doped MAPbI3 films decomposed slower than the Dodec-doped MAPbI3 films.

Experimental and Theoretical Investigations of MAPbX3 -Based Perovskites (X=Cl, Br, I) for Photovoltaic Applications.

This work mainly focuses on synthesizing and evaluating the efficiency of methylammonium lead halide-based perovskite (MAPbX3 ; X=Cl, Br, I) solar cells. We used the colloidal Hot-injection method (HIM) to synthesize MAPbX3 (X=Cl, Br, I) perovskites using the specific precursors and organic solvents under ambient conditions. We studied the structural, morphological and optical properties of MAPbX3 perovskites using XRD, FESEM, TEM, UV-Vis, PL and TRPL (time-resolved photoluminescence) characterization techniques. The particle size and morphology of these perovskites vary with respect to the halide variation. The MAPbI3 perovskite possesses a low band gap and low carrier lifetime but delivers the highest PCE among other halide perovskite samples, making it a promising candidate for solar cell technology. To further enrich the investigations, the conversion efficiency of the MAPbX3 perovskites has been evaluated through extensive device simulations. Here, the optical constants, band gap energy and carrier lifetime of MAPbX3 were used for simulating three different perovskite solar cells, namely I, Cl or Br halide-based perovskite solar cells. MAPbI3 , MAPbBr3 and MAPbCl3 absorber layer-based devices showed ~13.7 %, 6.9 % and 5.0 % conversion efficiency. The correlation between the experimental and SCAPS simulation data for HIM-synthesized MAPBX3 -based perovskites has been reported for the first time.