Publications by Henry Snaith

Facile Synthesis of Stable and Highly Luminescent Methylammonium Lead Halide Nanocrystals for Efficient Light Emitting Devices.

Journal of the American Chemical Society (2019)

Y Hassan, OJ Ashton, JH Park, G Li, N Sakai, B Wenger, A-A Haghighirad, NK Noel, MH Song, BR Lee, RH Friend, HJ Snaith

Metal halide perovskites are promising candidates for use in light emitting diodes (LEDs), due to their potential for colour tuneable and high luminescence efficiency. While recent advances in perovskite-based light emitting diodes have resulted in external quantum efficiencies exceeding 12.4 % for the green emitters, and infrared emitters based on 3D/2D mixed dimensional perovskites have exceeded 20%, the external quantum efficiencies of the red and blue emitters still lag behind. A critical issue to date is creating highly emissive and stable perovskite emitters with the desirable emission band gap to achieve full-colour displays and white LEDs. Herein, we report the preparation and characterization of a highly luminescent and stable suspension of cubic-shaped methylammonium lead triiodide CH3NH3PbI3 perovskite nanocrystals, where we synthesise the nanocrystals via a ligand-assisted re-precipitation technique, using an acetonitrile/methylamine compound solvent system to solvate the ions, and toluene as the anti-solvent to induce crystallisation. Through tuning the ratio of the ligands, the ligand to toluene ratio, and the temperature of the toluene, we obtain a solution of CH3NH3PbI3 nanocrystals with a photoluminescence quantum yield exceeding 93%, and tuneable emission between 660 nm and 705 nm. We also achieved red emission at 635 nm by blending the nanocrystals with bromide salt and obtained perovskite-based light emitting diodes with maximum electroluminescent external quantum efficiency of 2.75%.

Structural and Optical Properties of Cs2AgBiBr6 Double Perovskite

ACS ENERGY LETTERS 4 (2019) 299-305

L Schade, AD Wright, RD Johnson, M Dollmann, B Wenger, PK Nayak, D Prabhakaran, LM Herz, R Nicholas, HJ Snaith, PG Radaelli

Direct Observation of Ultrafast Exciton Dissociation in Lead Iodide Perovskite by 2D Electronic Spectroscopy

ACS PHOTONICS 5 (2018) 852-860

A Jha, H-G Duan, V Tiwari, PK Nayak, HJ Snaith, M Thorwart, RJD Miller

Surface modified fullerene electron transport layers for stable and reproducible flexible perovskite solar cells

NANO ENERGY 49 (2018) 324-332

S Song, R Hill, K Choi, K Wojciechowski, S Barlow, J Leisen, HJ Snaith, SR Marder, T Park

Aligned and Graded Type-II Ruddlesden-Popper Perovskite Films for Efficient Solar Cells


J Qing, X-K Liu, M Li, F Liu, Z Yuan, E Tiukalova, Z Yan, M Duchamp, S Chen, Y Wang, S Bai, J-M Liu, HJ Snaith, C-S Lee, TC Sum, F Gao

The effect of ionic composition on acoustic phonon speeds in hybrid perovskites from Brillouin spectroscopy and density functional theory


IV Kabakova, I Azuri, Z Chen, PK Nayak, HJ Snaith, L Kronik, C Paterson, AA Bakulin, DA Egger

Present status and future prospects of perovskite photovoltaics.

Nature materials 17 (2018) 372-376

HJ Snaith

High irradiance performance of metal halide perovskites for concentrator photovoltaics (vol 3, pg 855, 2018)

NATURE ENERGY 3 (2018) 1013-1013

Z Wang, Q Lin, B Wenger, MG Christoforo, Y-H Lin, MT Klug, MB Johnston, LM Herz, HJ Snaith

In situ simultaneous photovoltaic and structural evolution of perovskite solar cells during film formation


M Alsari, O Bikondoa, J Bishop, M Abdi-Jalebi, LY Ozer, M Hampton, P Thompson, MT Horantner, S Mahesh, C Greenland, JE Macdonald, G Palmisano, HJ Snaith, DG Lidzey, SD Stranks, RH Frienda, S Lilliu

Evidence of Nitrogen Contribution to the Electronic Structure of the CH3 NH3 PbI3 Perovskite.

Chemistry (Weinheim an der Bergstrasse, Germany) 24 (2018) 3539-3544

M Kot, K Wojciechowski, H Snaith, D Schmeißer

Despite fast development of hybrid perovskite solar cells, there are many fundamental questions related to the perovskite film which remain open. For example, there are contradicting theoretical reports on the role of the organic methylammonium cation (CH3 NH3+ ) in the methylammonium lead triiodide (CH3 NH3 PbI3 ) perovskite film. From one side it is reported that the organic cation does not contribute to electronic structure of the CH3 NH3 PbI3 film. From the other side, valence band maximum fluctuations, dependent on the CH3 NH3+ rotation, have been theoretically predicted. The resonant X-ray photoelectron spectroscopy results reported here show experimental evidence of nitrogen contribution to the CH3 NH3 PbI3 electronic structure. Moreover, the observed strong resonances of nitrogen with the I 5s and the Pb 5d-6s levels indicate that the CH3 NH3 PbI3 valence band is extended up to ≈18 eV below the Fermi energy, and therefore one should also consider these shallow core levels while modeling its electronic structure.

Perovskite/Colloidal Quantum Dot Tandem Solar Cells: Theoretical Modeling and Monolithic Structure

ACS ENERGY LETTERS 3 (2018) 869-874

A Karani, L Yang, S Bai, MH Futscher, HJ Snaith, B Ehrler, NC Greenham, D Di

Nonspiro, Fluorene-Based, Amorphous Hole Transporting Materials for Efficient and Stable Perovskite Solar Cells.

Advanced science (Weinheim, Baden-Wurttemberg, Germany) 5 (2018) 1700811-

Š Daškevičiū Tė, N Sakai, M Franckevičius, M Daškevičienė, A Magomedov, V Jankauskas, HJ Snaith, V Getautis

Novel nonspiro, fluorene-based, small-molecule hole transporting materials (HTMs) V1050 and V1061 are designed and synthesized using a facile three-step synthetic route. The synthesized compounds exhibit amorphous nature with a high glass transition temperature, a good solubility, and decent thermal stability. The planar perovskite solar cells (PSCs) employing V1050 generated an excellent power conversion efficiency of 18.3%, which is comparable to 18.9% obtained with the state-of-the-art Spiro-OMeTAD. Importantly, the devices based on V1050 and V1061 show better stability compared to devices based on Spiro-OMeTAD when aged without any encapsulation under uncontrolled humidity conditions (relative humidity around 60%) in the dark and under continuous full sun illumination.

Enabling reliability assessments of pre-commercial perovskite photovoltaics with lessons learned from industrial standards

NATURE ENERGY 3 (2018) 459-465

HJ Snaith, P Hacke

Correction to "Exciton-Dominated Core-Level Absorption Spectra of Hybrid Organic-Inorganic Lead Halide Perovskites".

The journal of physical chemistry letters 9 (2018) 3193-

C Vorwerk, C Hartmann, C Cocchi, G Sadoughi, SN Habisreutinger, R Félix, RG Wilks, HJ Snaith, M Bär, C Draxl

Enhanced photovoltage for inverted planar heterojunction perovskite solar cells.

Science (New York, N.Y.) 360 (2018) 1442-1446

D Luo, W Yang, Z Wang, A Sadhanala, Q Hu, R Su, R Shivanna, GF Trindade, JF Watts, Z Xu, T Liu, K Chen, F Ye, P Wu, L Zhao, J Wu, Y Tu, Y Zhang, X Yang, W Zhang, RH Friend, Q Gong, HJ Snaith, R Zhu

The highest power conversion efficiencies (PCEs) reported for perovskite solar cells (PSCs) with inverted planar structures are still inferior to those of PSCs with regular structures, mainly because of lower open-circuit voltages (Voc). Here we report a strategy to reduce nonradiative recombination for the inverted devices, based on a simple solution-processed secondary growth technique. This approach produces a wider bandgap top layer and a more n-type perovskite film, which mitigates nonradiative recombination, leading to an increase in Voc by up to 100 millivolts. We achieved a high Voc of 1.21 volts without sacrificing photocurrent, corresponding to a voltage deficit of 0.41 volts at a bandgap of 1.62 electron volts. This improvement led to a stabilized power output approaching 21% at the maximum power point.

Exciton-Dominated Core-Level Absorption Spectra of Hybrid Organic-Inorganic Lead Halide Perovskites.

The journal of physical chemistry letters 9 (2018) 1852-1858

C Vorwerk, C Hartmann, C Cocchi, G Sadoughi, SN Habisreutinger, R Félix, RG Wilks, HJ Snaith, M Bär, C Draxl

In a combined theoretical and experimental work, we investigate X-ray absorption near-edge structure spectroscopy of the I L3 and the Pb M5 edges of the methylammonium lead iodide (MAPbI3) hybrid inorganic-organic perovskite and its binary phase PbI2. The absorption onsets are dominated by bound excitons with sizable binding energies of a few hundred millielectronvolts and pronounced anisotropy. The spectra of both materials exhibit remarkable similarities, suggesting that the fingerprints of core excitations in MAPbI3 are essentially given by its inorganic component, with negligible influence from the organic groups. The theoretical analysis complementing experimental observations provides the conceptual insights required for a full characterization of this complex material.

Investigating the Role of 4-Tert Butylpyridine in Perovskite Solar Cells


SN Habisreutinger, NK Noel, HJ Snaith, RJ Nicholas

Trends in Perovskite Solar Cells and Optoelectronics: Status of Research and Applications from the PSCO Conference

ACS ENERGY LETTERS 2 (2017) 857-861

F De Angelis, D Meggiolaro, E Mosconi, A Petrozza, MK Nazeeruddin, HJ Snaith

Efficient and Air-Stable Mixed-Cation Lead Mixed-Halide Perovskite Solar Cells with n-Doped Organic Electron Extraction Layers.

Advanced materials (Deerfield Beach, Fla.) 29 (2017)

Z Wang, DP McMeekin, N Sakai, S van Reenen, K Wojciechowski, JB Patel, MB Johnston, HJ Snaith

Air-stable doping of the n-type fullerene layer in an n-i-p planar heterojunction perovskite device is capable of enhancing device efficiency and improving device stability. Employing a (HC(NH2 )2 )0.83 Cs0.17 Pb(I0.6 Br0.4 )3 perovskite as the photoactive layer, glass-glass laminated devices are reported, which sustain 80% of their "post burn-in" efficiency over 3400 h under full sun illumination in ambient conditions.

Electron injection and scaffold effects in perovskite solar cells.

Journal of materials chemistry. C 5 (2017) 634-644

M Anaya, W Zhang, BC Hames, Y Li, F Fabregat-Santiago, ME Calvo, HJ Snaith, H Míguez, I Mora-Seró

In spite of the impressive efficiencies reported for perovskite solar cells (PSCs), key aspects of their working principles, such as electron injection at the contacts or the suitability of the utilization of a specific scaffold layer, are not yet fully understood. Increasingly complex scaffolds attained by the sequential deposition of TiO2 and SiO2 mesoporous layers onto transparent conducting substrates are used to perform a systematic characterization of both the injection process at the electron selective contact and the scaffold effect in PSCs. By forcing multiple electron injection processes at a controlled sequence of perovskite-TiO2 interfaces before extraction, interfacial injection effects are magnified and hence characterized in detail. An anomalous injection behavior is observed, the fingerprint of which is the presence of significant inductive loops in the impedance spectra with a magnitude that correlates with the number of interfaces in the scaffold. Analysis of the resistive and capacitive behavior of the impedance spectra indicates that the scaffolds could hinder ion migration, with positive consequences such as lowering the recombination rate and implications for the current-potential curve hysteresis. Our results suggest that an appropriate balance between these advantageous effects and the unavoidable charge transport resistive losses introduced by the scaffolds will help in the optimization of PSC performance.