MAPbI3 Layer Research Articles

Enhancing the c-TiO2 based perovskite solar cell performance via modification by a serial of boronic acid derivative self-assembled monolayers

Morphological control of MAPbI3 crystal growth is one of the most important factor to fabricate high efficient perovskite solar cells. Herein, different boronic acid derivative self-assemble monolayers were used for modification of c-TiO2 surface and controlling of interface properties between c-TiO2 and MAPbI3 layers. Pre-mixed MAPbI3 solution in GBL was deposited by spin-coating technique onto non-modified and modified c-TiO2 surfaces by selected SAMs. The 1-OMe modified c-TiO2 based solar cell shows an increase in Jsc, resulting an increase to 9.4% PCE to compare with 5.9% PCE of non-modified c-TiO2 based solar cell. With this work, we demonstrated the possibility of morphological control of perovskite layer by using simple modification method of sublayer to increase the photovoltaic characteristics of solar cells.

Revealing a Discontinuity in the Degradation Behavior of CH3NH3PbI3 during Thermal Operation

The advance of innovative photovoltaics based on hybrid perovskites is currently forced to face their stability and durability through the rationalization of the phenomena occurring into the lattice under conditions which mimic the material operation. In this framework, we study the structural modifications of MAPbI3 layers by in situ structural and optical analyses upon recursive thermal cycles from 30 to 80 °C in different annealing environments. We reveal an acceleration of the material modification, above what expected, as the threshold of the tetragonal to cubic transition (∼50 °C) is surpassed. This produces discontinuities in the degradation rate, bandgap value, and dielectric behavior of the MAPbI3 layer. The phenomenon is put in relationship with the order–disorder lattice modifications described by Car–Parrinello molecular dynamics calculations and reveals that the action of species from humid air becomes largely more effective above 50 °C for reasons related to the increased accessibility/react...

On-axis pulsed laser deposition of hybrid perovskite films for solar cell and broadband photo-sensor applications

High quality hybrid perovskite films are grown by the pulsed laser deposition (PLD) process through target stoichiometry and gas ambient control in the commonly used on-axis geometry which is compatible with PLD of other materials such as metal oxides. The use of an off-stoichiometric target and a momentum softening gas mixture of argon and hydrogen (90%:10%) is shown to yield dense films in the on-axis geometry with excellent stoichiometry and optical quality. The band gap can be easily tuned from 1.6 to 2.3 eV with either mixed halide composite target or successive depositions of inter-diffusing MAPbBr3 and MAPbI3 layers. A photosensor based on PLD grown MAPbI3 is shown to render impressive performance over the broad range of wavelengths from 375 to 800 nm at a voltage of 5 V bias. A planar heterojunction solar cell based on the dry-processed on-axis PLD grown film exhibits a champion conversion efficiency of 10.9%. A heterostructure comprising in situ pulsed laser deposited Cu2O (p-type) followed by the hybrid perovskite film shows a rectifying characteristic and photoresponse.

Correction to “Interfacial Electronic Structure of Methylammonium Lead Iodide Grown on a Mesoporous TiO2 Layer on F-Doped Tin Oxide Substrate”

Interfacial electronic structure at the perovskite CH3NH3PbI3/TiO2 or MAPbI3/TiO2 interface has been investigated using a high-resolution synchrotron photoemission spectroscopy. The core levels and valence band spectra of our solution-processed MAPbI3 layers spin-coated on a mesoporous TiO2 substrate are consistent with a pure iodide perovskite (MAPbI3) with residual methylammonium (CH3NH3+) trapped within the perovskite crystal lattice, which is in contact with TiO2. In addition, we show spectroscopic evidence for the presence of PbI2 and methylamine (CH3NH2) at the MAPbI3/TiO2 interface. Interestingly, the Fermi level (EF) aligned to the conduction band minimum (CBM) of both layers is found to be lifted via a band bending which may be attributed to characteristic chemical bonding structures at the interface. The band bending may act as an electron transfer barrier between MAPbI3 and TiO2. Thus, our findings in interfacial electronic structure of MAPbI3 layers on TiO2 will be crucial in understanding its...

An Investigation of the Energy Levels within a Common Perovskite Solar Cell Device and a Comparison of DC/AC Surface Photovoltage Spectroscopy Kelvin Probe Measurements of Different MAPBI3 Perovskite Solar Cell Device Structures

ABSTRACTWe present a study of the energy levels in a FTO/TiO2/CH3NH3PbI3/Spiro solar cell device. The measurements are performed using a novel ambient pressure photoemission (APS) technique alongside Contact Potential Difference data from a Kelvin Probe. The Perovskite Solar Cell energy band diagram is demonstrated for the device in dark conditions and under illumination from a 150W Quartz Tungsten Halogen lamp. This approach provides useful information on the interaction between the different materials in this solar cell device. Additionally, non-destructive macroscopic DC and AC Surface Photovoltage Spectroscopy (SPS) studies are demonstrated of different MAPBI3 device structures to give an indication of overall device performance. AC-SPS measurements, previously used on traditional semiconductors to study the mobility, are used in this case to characterise the ability of a perovskite solar cell device to respond rapidly to chopped light. Two different device structures studied showed very different characteristics: Sample A (without TiO2): (ITO/PEDOT:PSS/polyTPD/CH3NH3PbI3/PCBM) had ∼4 times the magnitude of AC-SPS response compared to Sample B (including TiO2): (ITO/TiO2/ CH3NH3PbI3/Spiro). This demonstrates that the carrier speed characteristics of device architecture A is superior to device architecture B. The TiO2 layer has been associated with carrier trapping which is illustrated in this example. However, the DC-SPV performance of sample B is ∼5 times greater than that of sample A. The band gap of the MAPBI3 layer was determined through DC-SPS (1.57 ± 0.07 eV), Voc of the devices measured and qualitative observations made of interface trapping by DC light pulsing. The combination of these (APS, KP, AC/DC-SPV/SPS) techniques offers a more general method for measuring the energy level alignments and performance of Organic and Hybrid Solar Cell Devices.

Hole‐extraction layer dependence of defect formation and operation of planar CH3NH3PbI3 perovskite solar cells

Three planar CH3NH3PbI3 (MAPbI3) solar cells having the same structure except a hole‐extraction layer (HEL) showed distinctive difference in operation characteristics. Analysis of frequency‐dependent capacitance and dielectric‐loss spectra of the three MAPbI3 devices showed two types of recombination‐loss channels with different time constants that we attributed respectively to interface and bulk defects. Discrepancy in defect formation among the three devices with a HEL of PEDOT:PSS, NiOx, or Cu‐doped NiOx was not surprising because grain‐size distribution and crystalline quality of MAPbI3 can be affected by surface energy and morphology of underlying HELs. We were able to quantify interface and bulk defects in these MAPbI3solar cells based on systematic and simultaneous simulations of capacitance and dielectric‐loss spectra, and current–voltage characteristics by using the device simulator SCAPS. magnified imageDefect density reduction is essential for efficient planar solar cells. Defect density in MAPbI3 layers, with respect to which an open‐cell voltage and a fill factor vary, can be investigated by using capacitance–frequency spectra.

Formation of Perovskite Heterostructures by Ion Exchange

Thin-film optoelectronic devices based on polycrystalline organolead-halide perovskites have recently become a topic of intense research. Single crystals of these materials have been grown from solution with electrical properties superior to those of polycrystalline films. In order to enable the development of more complex device architectures based on organolead-halide perovskite single crystals, we developed a process to form epitaxial layers of methylammonium lead iodide (MAPbI3) on methylammonium lead bromide (MAPbBr3) single crystals. The formation of the MAPbI3 layer is found to be dominated by the diffusion of halide ions, leading to a shift in the photoluminescence and absorption spectra. X-ray diffraction measurements confirm the single-crystal nature of the MAPbI3 layer, while carrier transport measurements show that the converted layer retains the high carrier mobility typical of single-crystal perovskite materials. Such heterostructures on perovskite single crystals open possibilities for new types of devices.

Multiferroic Nanohybrid MAPbI3/P3HT Nanowire Complex

Room-temperature multiferroic effects in organic materials have brought more attention in the area of organic spintronics and organic electronics in recent years. In this work, through fabricating MAPbI3/P3HT nanowire nanohybrid complex, the mechanisms of room-temperature ferromagnetism and magnetoelectric coupling are studied. The MAPbI3 layer provides substantial photogenerated carriers charging into the nw-P3HT layer, where the P3HT nanowire structure induces carrier spins aligning to generate room temperature ferromagnetism. Through controlling the strength of external electric field, magnetization of the MAPbI3/P3HT nanowire complex is modified due to the electric field driven carrier spins redistribution. Additionally, photon spin of circularly polarized light could interact with electron spin in organic multiferroics to enhance saturation magnetization at room temperature.

Modification of Ultrathin NPB Interlayer on the Electronic Structures of the CH3NH3PbI3/NPB/MoO3 Interface

Modification of the ultrathin N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) insertion layer on the electronic structures of the CH3NH3PbI3 (MAPbI3)/MoO3 interfaces is investigated using ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). It is found that when an ultrathin NPB insertion layer of 16 Å is inserted between MAPbI3 and MoO3, the chemical reaction between the latter two can be effectively suppressed, and a favorable energy-level alignment is achieved. The valence band maximum (VBM) or highest occupied molecular orbital (HOMO) at the MAPbI3/NPB/MoO3 interface facilitates the hole transportation from the MAPbI3 layer through the NPB layer toward the NPB/MoO3 interface. As a result, the holes can be efficiently extracted to the hole collection electrode due to the small energy offset between the conduction band minimum (CBM) of MoO3 and the HOMO of NPB. Therefore, the modification by the ultrathin NPB interlayer on the electronic structures of the MAPbI3/MoO3 interface can greatly improve the hole extraction and thus enhance the power efficiency of the corresponding solar cells.

Electric field-modulated amplified spontaneous emission in organo-lead halide perovskite CH3NH3PbI3

The electric field-modulation of the spontaneous emission (SE) and amplified spontaneous emission (ASE) in organo-lead halide perovskite CH3NH3PbI3 (aliased as MAPbI3) layer has been investigated. With the increase of the external applied electric field, the electric field-induced quenching of the SE and ASE intensity was observed, accompanying with a blue-shift of the ASE emission peaks, which can be attributed to field-induced ionization of photogenerated excitons in the MAPbI3 layer. Based on the analysis of quenching factor and the dielectric constant, we estimated an exciton binding energy ∼36 meV at room temperature, which will provide useful insights into the optical-electrical characteristics of MAPbI3 and pave the way for the future optoelectronic applications.

Correction to “Texture of MAPbI3 Layers Assisted by Chloride on Flat TiO2 Substrates”

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionCorrection to “Texture of MAPbI3 Layers Assisted by Chloride on Flat TiO2 Substrates”Giovanna Pellegrino, Silvia Colella, Ioannis Deretzis, Guglielmo G. Condorelli, Emanuele Smecca, Giuseppe Gigli, Antonino La Magna, and Alessandra Alberti*Cite this: J. Phys. Chem. C 2015, 119, 37, 21745Publication Date (Web):September 8, 2015Publication History Published online8 September 2015Published inissue 17 September 2015https://doi.org/10.1021/acs.jpcc.5b08573Copyright © 2015 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views284Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (108 KB) Get e-Alerts Get e-Alerts