Methylammonium Triiodide for Defect Engineering of High-Efficiency Perovskite Solar Cells

Related publications (39)

Guanine‐Stabilized Formamidinium Lead Iodide Perovskites

Paramvir Ahlawat, David Lyndon Emsley, Ulf Anders Hagfeldt, Li Hong, Dominik Józef Kubicki, Yuhang Liu, Jovana Milic, Marko Mladenovic, Linfeng Pan, Dan Ren, Ursula Röthlisberger, Marco Alejandro Ruiz Preciado, Amita Ummadisingu, Shaik Mohammed Zakeeruddin

Formamidinium (FA) lead iodide perovskite materials feature promising photovoltaic performances and superior thermal stabilities. However, conversion of the perovskite α‐FAPbI3 phase to the thermodynamically stable yet photovoltaically inactive δ‐FAPbI3 phase compromises the photovoltaic performance. A strategy is presented to address this challenge by using low‐dimensional hybrid perovskite materials comprising guaninium (G) organic spacer layers that act as stabilizers of the three‐dimensional α‐FAPbI3 phase. The underlying mode of interaction at the atomic level is unraveled by means of solid‐state nuclear magnetic resonance spectroscopy, X‐ray crystallography, transmission electron microscopy, molecular dynamics simulations, and DFT calculations. Low‐dimensional‐phase‐containing hybrid FAPbI3 perovskite solar cells are obtained with improved performance and enhanced long‐term stability.

2020

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High photovoltage in perovskite solar cells (PSCs) can be achieved by designing new hole transporting materials (HTMs) with relatively deeper energy levels of the highest occupied molecular orbital (HOMO). Here, we report on the synthesis of a new heteroacene-based HTM (HTM-1) and demonstrate its potential in the fabrication of FAPbBr(3) [FA = CH(NH2)(2)] PSCs yielding V-OC as high as 1.55 V, a record value for this light harvester. The energetic position of the frontier orbitals of HTM-1 was estimated using electrochemical measurements, and the charge transport across the interfaces was studied using steady-state and time-resolved photoluminescence. When spiro-OMeTAD (HOMO = -5.1 eV) is replaced with HTM-1 (HOMO = -5.3 eV), the V-OC increases from 1.51 to 1.55 V, whereas the J(SC) value decreases from 7.0 to 5.7 mA cm(-2). The similar trade-off between J(SC) and V-OC is observed for efficient iodide-based PSCs, suggesting that there is a critical energy level for the HOMO below which overall photovoltaic performance will suffer. After probing at a maximum power point under full-sun illumination at 60 degrees C for a duration of 120 h, the FAPbBr(3) PSCs based on HTM-1 retained approximate to 95 % of their initial efficiency, which demonstrates their robust operational stability.

WILEY-V C H VERLAG GMBH2018

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Pb-free Sn-based perovskite solar cells (PSCs) have significant potential for application in photovoltaic devices because oftheir suitable bandgap, low exciton binding energy, high carrier mobility, and long diffusion length. However, their performance is hampered by several issues. Sn-based perovskites are highly susceptible to oxidation, which induces a high concentration of defects and degrades the chemical stability of the perovskite crystals. Herein, the anion formate (HCOO-) can effectively suppress the oxidation of Sn in the pure formamidinium tin triiodide (FASnI(3)) perovskite without using A-site cationic additives. Moreover, the presence of formate results in a uniform pinhole-free perovskite film with a low trap density, reduced charge carrier recombination, and improved charge extraction. Density functional theory calculations show that formate-treated FASnI(3) has improved stability against oxidative Sn degradation. The formate-treated PSC achieves a power conversion efficiency of 12.11% at a high open-circuit voltage of 0.71 V. The device exhibits improved stability in ambient air in which it maintained over 80% of its initial power conversion efficiency after 180 min because oxidation is inhibited owing to the strong interaction between Sn and formate.

WILEY-V C H VERLAG GMBH2022

Naphthalenediimide/Formamidinium-Based Low-Dimensional Perovskites

Paramvir Ahlawat, Masaud Hassan S Almalki, Vincent Henri Guillaume Dufoulon, David Lyndon Emsley, George Cameron Fish, Michael Graetzel, Farzaneh Jahanbakhshi, Dominik Józef Kubicki, Jovana Milic, Aditya Mishra, Marko Mladenovic, Jacques-Edouard Moser, Ursula Röthlisberger, Marco Alejandro Ruiz Preciado, Thomas Schneeberger, Pascal Alexander Schouwink, Shaik Mohammed Zakeeruddin

Low-dimensional hybrid perovskites have emerged as promising materials for optoelectronic applications. Although these materials have already demonstrated enhanced stability as compared to their three-dimensional perovskite analogues, their functionality has been limited by the insulating character of the organic moieties that primarily play a structure-directing role. This is particularly the case for the layered (2D) perovskite materials based on formamidinium lead iodide (FAPbI3) that remain scarce. We demonstrate a low-dimensional hybrid perovskite material based on a SPbI4 composition incorporating an electroactive naphthalenediimide (NDI) moiety as an organic spacer (S) between the perovskite slabs and evidence the propensity of the spacer to stabilize the α-FAPbI3 perovskite phase in hybrid low-dimensional SFAn–1PbnI3n+1 perovskite compositions. This has been investigated by means of solid-state nuclear magnetic resonance spectroscopy in conjunction with molecular dynamics simulations and density functional theory calculations. Theoretical calculations suggest an electronic contribution of the organic spacer to the resulting optoelectronic properties, which was confirmed by transient absorption spectroscopy. We have further analyzed these materials by time-resolved microwave conductivity measurements, revealing challenges for their application in photovoltaics.

2021

Defect Passivation via the Incorporation of Tetrapropylammonium Cation Leading to Stability Enhancement in Lead Halide Perovskite

Anurag Krishna

Improving the performances of photovoltaic (PV) devices by suppressing nonradiative energy losses through surface defect passivation and enhancing the stability to the level of standard PV represents one critical challenge for perovskite solar cells. Here, reported are the advantages of introducing a tetrapropylammonium (TPA(+)) cation that combines two key functionalities, namely surface passivation of CH3NH3PbI3 nanocrystals through strong ionic interaction with the surface and bulk passivation via formation of a type I heterostructure that acts as a recombination barrier. As a result, nonencapsulated perovskite devices with only 2 mol% of TPA(+) achieve power conversion efficiencies over 18.5% with higher V-OC under air mass 1.5G conditions. The devices fabricated retain more than 85% of their initial performances for over 1500 h under ambient conditions (55% RH +/- 5%). Furthermore, devices with TPA(+) also exhibit excellent operational stability by retaining over 85% of the initial performance after 250 h at maximum power point under 1 sun illumination. The effect of incorporation of TPA(+) on the structural and optoelectronic properties is studied by X-ray diffraction, ultraviolet-visible absorption spectroscopy, ultraviolet photon-electron spectroscopy, time-resolved photoluminescence, and scanning electron microscopy imaging. Atomic-level passivation upon addition of TPA(+) is elucidated employing 2D solid-state NMR spectroscopy.

WILEY-V C H VERLAG GMBH2020

Nanoscale Phase Segregation in Supramolecular π-Templating for Hybrid Perovskite Photovoltaics from NMR Crystallography

Paramvir Ahlawat, Loï Charles Carbone, Brian Irving Carlsen, Manuel Cordova, David Lyndon Emsley, Ulf Anders Hagfeldt, Michael Allan Hope, Farzaneh Jahanbakhshi, Dominik Józef Kubicki, Yuhang Liu, Jovana Milic, Aditya Mishra, Marko Mladenovic, Toru Nakamura, Ursula Röthlisberger, Rashmi Runjhun, Thomas Schneeberger, Shaik Mohammed Zakeeruddin

The use of layered perovskites is an important strategy to improve the stability of hybrid perovskite materials and their optoelectronic devices. However, tailoring their properties requires accurate structure determination at the atomic scale, which is a challenge for conventional diffraction-based techniques. We demonstrate the use of nuclear magnetic resonance (NMR) crystallography in determining the structure of layered hybrid perovskites for a mixed-spacer model composed of 2-phenylethylammonium (PEA+) and 2-(perfluorophenyl)ethylammonium (FEA+) moieties, revealing nanoscale phase segregation. Moreover, we illustrate the application of this structure in perovskite solar cells with power conversion efficiencies that exceed 21%, accompanied by enhanced operational stability.

2021

Origin of unusual bandgap shift and dual emission in organic-inorganic lead halide perovskites

Neha Arora, Ariadni Boziki, Mohammad Ibrahim Dar, Michael Graetzel, Gwénolé Jean Jacopin, Simone Meloni, Ursula Röthlisberger, Shaik Mohammed Zakeeruddin

Emission characteristics of metal halide perovskites play a key role in the current widespread investigations into their potential uses in optoelectronics and photonics. However, a fundamental understanding of the molecular origin of the unusual blueshift of the bandgap and dual emission in perovskites is still lacking. In this direction, we investigated the extraordinary photoluminescence behavior of three representatives of this important class of photonic materials, that is, CH3NH3PbI3, CH3NH3PbBr3, and CH(NH2)(2)PbBr3, which emerged from our thorough studies of the effects of temperature on their bandgap and emission decay dynamics using time-integrated and time-resolved photoluminescence spectroscopy. The low-temperature (

2016

Atomic-Level Microstructure of Efficient Formamidinium-Based Perovskite Solar Cells Stabilized by 5-Ammonium Valeric Acid Iodide Revealed by Multinuclear and Two-Dimensional Solid-State NMR

Anwar Qasem M Alanazi, Essa Awadh R Alharbi, Marine Eva Fedora Bouduban, David Lyndon Emsley, Fabrizio Giordano, Michael Graetzel, Farzaneh Jahanbakhshi, Dominik Józef Kubicki, Jovana Milic, Marko Mladenovic, Jacques-Edouard Moser, Daniel Prochowicz, Dan Ren, Ursula Röthlisberger, Shaik Mohammed Zakeeruddin

Chemical doping of inorganic–organic hybrid perovskites is an effective way of improving the performance and operational stability of perovskite solar cells (PSCs). Here we use 5-ammonium valeric acid iodide (AVAI) to chemically stabilize the structure of α-FAPbI3. Using solid-state MAS NMR, we demonstrate the atomic-level interaction between the molecular modulator and the perovskite lattice and propose a structural model of the stabilized three-dimensional structure, further aided by density functional theory (DFT) calculations. We find that one-step deposition of the perovskite in the presence of AVAI produces highly crystalline films with large, micrometer-sized grains and enhanced charge-carrier lifetimes, as probed by transient absorption spectroscopy. As a result, we achieve greatly enhanced solar cell performance for the optimized AVA-based devices with a maximum power conversion efficiency (PCE) of 18.94%. The devices retain 90% of the initial efficiency after 300 h under continuous white light illumination and maximum-power point-tracking measurement.

2019

Guanine‐Stabilized Formamidinium Lead Iodide Perovskites

Paramvir Ahlawat, David Lyndon Emsley, Michael Graetzel, Ulf Anders Hagfeldt, Dominik Józef Kubicki, Yuhang Liu, Jovana Milic, Marko Mladenovic, Linfeng Pan, Dan Ren, Ursula Röthlisberger, Marco Alejandro Ruiz Preciado, Amita Ummadisingu, Shaik Mohammed Zakeeruddin

Wiley

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In the last decade, halide perovskites have emerged as new semiconductors that revolutionize the photovoltaic field. Among this family of materials, all-inorganic halide perovskites are becoming a research paradigm because of their outstanding photophysical properties combined with the potential of long-term stabilities against moisture and thermal stresses in practical applications. By forming high-quality inorganic halide perovskite thin films and stabilizing the three-dimensional perovskite phases, in the past few years, the state-of-the-art inorganic perovskite solar cells have achieved a power conversion efficiency of 20.37% and a promising long-term operation stability. In this review, based on the latest research progress of inorganic halide perovskites for photovoltaics, we summarized (1) the crystal structural, optical, and photophysical properties of materials; (2) the film formation methods; and (3) the stabilization strategies of inorganic perovskite phase, to provide useful guideline for fabricating devices with further enhanced performance and stability, and promoting commercial applications.

ELSEVIER2021