Perovskite solar cells (PSCs) are promising alternatives toward clean energy because of their high-power conversion efficiency (PCE) and low materials and processing cost. However, their poor stability under operation still limits their practical applicati ...

2018

Composition and Interface Engineering of Organic-Inorganic Hybrid Perovskites to Improve Photovoltaic Performance and Stability

Kyung Taek Cho

Faced with the growing demands for energy in modern society, organic-inorganic metal halide perovskite materials have recently fascinated the photovoltaics (PV) research community due to a combination of their high quality optoelectronic properties and the ...

EPFL2018

A Facile Preparative Route of Nanoscale Perovskites over Mesoporous Metal Oxide Films and Their Applications to Photosensitizers and Light Emitters

Mohammad Khaja Nazeeruddin, Emad Oveisi, Valentin Ianis Emmanuel Queloz, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Iwan Zimmermann, Aron Joel Huckaba, Giulia Grancini, So-Min Yoo

By two‐step sequential Pb2+ adsorption and reaction with methylammonium‐iodide (MAI) or ‐bromide (MABr) at a low concentration level of 0.06–0.10 m over mesoporous TiO2 or ZrO2 film, a well‐defined nanoscale CH3NH3PbI3 (MAPbI3) photosensitizer or CH3NH3PbB ...

2018

Intercalation makes the difference with TiS2: Boosting electrocatalytic water oxidation activity through Co intercalation

Mohammad Khaja Nazeeruddin, Emad Oveisi, Kyung Taek Cho, Aron Joel Huckaba

Intercalated and unmodified TiS2 nanomaterials were synthesized and characterized by UV-Visible-NIR spectroscopy, Powder X-Ray Diffraction, and X-Ray Photoelectron and Ultraviolet Photoelectron Spectroscopy. Photoelectron spectroscopy measurements indicate ...

2018

Water-Repellent Low-Dimensional Fluorous Perovskite as Interfacial Coating for 20% Efficient Solar Cells

Mohammad Khaja Nazeeruddin, Andreas Stephan Lesch, Kyung Taek Cho, Iwan Zimmermann, Giulia Grancini, Yi Zhang

Hybrid perovskite solar cells have been capturing an enormous research interest in the energy sector due to their extraordinary performances and ease of fabrication. However, low device lifetime, mainly due to material and device degradation upon water exp ...

American Chemical Society (ACS)2018

From Nano- to Micrometer Scale: The Role of Antisolvent Treatment on High Performance Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Francesco Stellacci, Peng Gao, Evangelia-Nefeli Athanasopoulou, Kyung Taek Cho, Sanghyun Paek, Giulia Grancini, Yi Zhang, Pascal Alexander Schouwink

To date, antisolvent treatment has become one of the most important means to fabricate high efficiency perovskite solar cells (PSCs); however, the few reported antisolvents have not been analyzed on a uniform platform, and there is hitherto no clear reason ...

American Chemical Society2017

Femtosecond Charge-Injection Dynamics at Hybrid Perovskite Interfaces

Mohammad Khaja Nazeeruddin, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Michael Saliba, Giulia Grancini

With a power conversion efficiency (PCE) exceeding 22%, perovskite solar cells (PSCs) have thrilled photovoltaic research. However, the interface behavior is still not understood and is a hot topic of research: different processes occur over a hierarchy of ...

Wiley-Blackwell2017

Analysis of Photoinduced Carrier Recombination Kinetics in Flat and Mesoporous Lead Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Kyung Taek Cho

In this work, we analyze the carrier recombination kinetics and the associated charge carrier density in methylammonium lead iodide perovskite (MAPI) solar cells that use mesoporous TiO2, as selective contact (m-MAPI) and flat solar cells (without the meso ...

Amer Chemical Soc2017

Molecular engineering of face-on oriented dopant-free hole transporting material for perovskite solar cells with 19% PCE

Mohammad Khaja Nazeeruddin, Paul Gratia, Peng Gao, Kasparas Rakstys, Kyung Taek Cho, Sanghyun Paek, Giulia Grancini

Through judicious molecular engineering, novel dopant-free star-shaped D-pi-A type hole transporting materials coded KR355, KR321, and KR353 were systematically designed, synthesized and characterized. KR321 has been revealed to form a particular face-on o ...

Royal Society of Chemistry2017

Molecularly Engineered Phthalocyanines as Hole-Transporting Materials in Perovskite Solar Cells Reaching Power Conversion Efficiency of 17.5%

Mohammad Khaja Nazeeruddin, Paul Gratia, Peng Gao, Kyung Taek Cho, Cristina Roldán Carmona, Giulia Grancini, Olga Trukhina

Easily accessible tetra-5-hexylthiophene-, tetra-5-hexyl-2,2'-bisthiophene-substituted zinc phthalocyanines (ZnPcs) and tetra-tert-Bu ZnPc are employed as hole-transporting materials in mixed-ion perovskite [HC(NH2)2]0.85(CH3NH3)0.15Pb(I0.8 ...

2017

Carbazole-based enamine: Low-cost and efficient hole transporting material for perovskite solar cells

Mohammad Khaja Nazeeruddin, Henry Snaith, Kasparas Rakstys, Kyung Taek Cho, Sanghyun Paek

A simple carbazole-based conjugated enamine V950 was synthesized, fully characterized and incorporated into a perovskite solar cell, which displayed high power conversion efficiency close to 18%. The investigated hole transporting material was synthesize ...

Elsevier Science Bv2017

Highly efficient perovskite solar cells with a compositionally engineered perovskite/hole transporting material interface

Mohammad Khaja Nazeeruddin, Peng Gao, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Cristina Roldán Carmona, Giulia Grancini

Perovskite solar cells (PSCs) have experienced an outstanding advance in power conversion efficiency (PCE) by optimizing the perovskite layer morphol., compn., interfaces, and charge collection efficiency. To enhance PCE, here we developed a new method i.e ...

Royal Soc Chemistry2017

Enhanced charge collection with passivation of the tin oxide layer in planar perovskite solar cells

Mohammad Khaja Nazeeruddin, Robin Humphry-Baker, Emad Oveisi, Peng Gao, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Yi Zhang

Tin oxide is an excellent candidate to replace mesoporous TiO2 electron transport layers (ETLs) in perovskite solar cells. Here, we introduced a SnO2 layer by a low-temperature solution process, and investigated its morphology, opto-physical and electrical ...

Royal Society of Chemistry2017

Dopant-Free Hole-Transporting Materials for Stable and Efficient Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Christian Ludwig, Paul Gratia, Emad Oveisi, Peng Gao, Peng Qin, Kasparas Rakstys, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek

Molecularly engineered novel dopant-free hole-transporting materials for perovskite solar cells (PSCs) combined with mixed-perovskite (FAPbI(3))(0.85)(MAPbBr(3))(0.15) (MA: CH3NH3+, FA: NH=CHNH3+) that exhibit an excellent power conversion efficiency of 18 ...

Wiley-V C H Verlag Gmbh2017

Enhanced Charge Collection with Passivation Layers in Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Shaik Mohammed Zakeeruddin, Peng Gao, Yonghui Lee, Jingshan Luo, Kyung Taek Cho, Minkyu Son, Jiyoun Seo

The Al2O3 passivation layer is beneficial for mesoporous TiO2-based perovskite solar cells when it is deposited selectively on the compact TiO2 surface. Such a passivation layer suppressing surface recombination can be formed by thermal decomposition of th ...

Wiley-V C H Verlag Gmbh2016

A highly hindered bithiophene-functionalized dispiro-oxepine derivative as an efficient hole transporting material for perovskite solar cells

Mohammad Khaja Nazeeruddin, Paul Gratia, Peng Gao, Kasparas Rakstys, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Muhammad Sohail

Dimethoxydiphenylamine-substituted dispiro-oxepine derivative 2,2',7,7'-tetrakis-(N,N'-di-4-methoxyphenylamine)dispiro-[fluorene-9,4'-dithieno(3,2-c:2',3'-e]oxepine-6',9 ''-fluorene] (DDOF) has been designed and synthesized using a facile synthetic route. ...

Royal Society of Chemistry2016

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