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Kasparas Rakstys

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Related publications (35)

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Fluorene-based enamines as low-cost and dopant-free hole transporting materials for high performance and stable perovskite solar cells

Mohammad Khaja Nazeeruddin, Kasparas Rakstys, Albertus Adrian Sutanto, Maria Cristina Momblona Rincón

The power conversion efficiency of perovskite solar cells is approaching the Shockley-Queisser limit, and therefore this technology is next to the commercialization stage. Inexpensive and stable hole transporting materials are highly desirable for the succ ...

Royal Society of Chemistry2021

Molecularly Engineered Hole Transporting Materials for High Performance Perovskite Solar Cells

Kasparas Rakstys

Perovskite solar cells have rapidly revolutionized the photovoltaic research showing an im-pressively dynamic progress on power conversion efficiency from 3.8 to 22% in only several years, a record for a nascent technology. Furthermore, inexpensive precurs ...

EPFL2018

Transparent Liquid Crystal Hole-Transporting Material for Stable Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Hiroyuki Kanda, Kasparas Rakstys, Jianxing Xia

Hexakis(hexyloxy)triphenylene (HAT6) discotic liquid crystal is employed as a transparent hole-transporting material (HTM) for perovskite solar cells (PSCs) and a power conversion efficiency (PCE) of 15.7% is obtained, which is the highest using HAT6 type ...

WILEY-V C H VERLAG GMBH2023

Green-Chemistry-Inspired Synthesis of Cyclobutane-Based Hole-Selective Materials for Highly Efficient Perovskite Solar Cells and Modules

Mohammad Khaja Nazeeruddin, Yi Zhang, Hiroyuki Kanda, Sanghyun Paek, Kasparas Rakstys

Hybrid lead halide perovskite solar cells (PSCs) have emerged as potential competitors to silicon-based solar cells with an unprecedented increase in power conversion efficiency (PCE), nearing the breakthrough point toward commercialization. However, for h ...

Wiley-VCH Verlag GmbH2022

Perovskite Solar Cells Employing Molecularly Engineered Zn(II) Phthalocyanines as Hole-transporting Materials

Mohammad Khaja Nazeeruddin, Kasparas Rakstys, Kyung Taek Cho

Amino donor groups-substituted zinc(II) phthalocyanines (ZnPcs) BI25, BL07 and BL08 were obtained via cyclotetramerization of suitable phthalonitriles that were synthesized by Pd catalyzed amination reaction between 4-iodophthalonitrile and a selected seco ...

Elsevier Science Bv2016

Rational design of triazatruxene-based hole conductors for perovskite solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Kasparas Rakstys

Triazatruxene core based hole transporting materials (HTMs), HMDI (5,10,15-trihexyl-3,8,13-trimethoxy-10,15-dihydro-5H-diindolo[3,2-a: 3',2'-c]carbazole) and HPDI (5,10,15-tris(4-(hexyloxy)phenyl)-10,15-dihydro-5H-diindolo[3,2-a: 3',2'-c]carbazole) were sy ...

Royal Soc Chemistry2015

Weakly Conjugated Hybrid Zinc Porphyrin Sensitizers for Solid-State Dye-Sensitized Solar Cells

Mohammad Khaja Nazeeruddin, Christian Ludwig, Mohammad Ibrahim Dar, Kasparas Rakstys, Peng Qin

Molecularly engineered weakly conjugated hybrid porphyrin systems are presented as efficient sensitizers for solid-state dye-sensitized solar cells. By incorporating the quinolizino acridine and triazatruxene based unit as the secondary light-harvester as ...

Wiley-Blackwell2016

Foldable Hole-Transporting Materials for Merging Electronic States between Defective and Perfect Perovskite Sites

Mohammad Khaja Nazeeruddin, Paul Joseph Dyson, Yi Zhang, Hiroyuki Kanda, Kasparas Rakstys, Jianxing Xia, Keith Gregory Brooks, Xiaoxin Gao

Defective and perfect sites naturally exist within electronic semiconductors, and considerable efforts to reduce defects to improve the performance of electronic devices, especially in hybrid organic-inorganic perovskites (ABX(3)), are undertaken. Herein, ...

Wiley-V C H Verlag Gmbh2023

Perovskite Solar Cells: 18% Efficiency Using Zn(II) and Cu(II) Octakis(diarylamine)phthalocyanines as Hole-Transporting Materials

Mohammad Khaja Nazeeruddin, Hiroyuki Kanda, Sanghyun Paek, Kyung Taek Cho, Kasparas Rakstys, Valentin Ianis Emmanuel Queloz, Marius Franckevicius

Metallophthalocyanines (MPcs) are currently emerging as alternative hole-transporting materials (HTMs) in perovskite solar cells (PSCs). However, the lack of systematic structure/photovoltaic properties investigations still hampers the rational design of M ...

2019

Low-Cost Perovskite Solar Cells Employing Dimethoxydiphenylamine-Substituted Bistricyclic Aromatic Enes as Hole Transport Materials

Mohammad Khaja Nazeeruddin, Peng Gao, Sanghyun Paek, Giulia Grancini, Kasparas Rakstys

The synthesis, characterization and photovoltaic performance of series of novel molecular hole transport materials (HTMs) based on bistricyclic aromatic enes (BAEs) are presented. The new derivatives were obtained following a simple and straightforward pro ...

Wiley-V C H Verlag Gmbh2017

Efficiency enhancement of perovskite solar cells via incorporation of phenylethenyl side arms into indolocarbazole-based hole transporting materials

Mohammad Khaja Nazeeruddin, Iwan Zimmermann, Kasparas Rakstys

Small-molecule hole transporting materials based on an indolocar-bazole core were synthesized and incorporated into perovskite solar cells, which displayed a power conversion efficiency up to 15.24%. The investigated hole transporting materials were synthe ...

Royal Soc Chemistry2016

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

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

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

Hole transporting organic molecules containing enamine groups for optoelectronic and photoelectrochemical devices

Sanghyun Paek, Kasparas Rakstys

The present invention relates to a compound of formula (I) based on enamine derivatives and used as organic hole conductors or hole transporting material in an optoelectronic or photoelectrochemical device. The present invention relates to the hole transpo ...

2018

Pyridination of hole transporting material in perovskite solar cells questions the long-term stability

Mohammad Khaja Nazeeruddin, Sanghyun Paek, Natalia Gasilova, Kasparas Rakstys

In this work, for the first time, reactive radical-cation species present in hole-transporting materials were shown to react with tert-butylpyridine additive, routinely used in hole transporting layer composition. As a result, new pyridinated products were ...

Royal Society of Chemistry2018

D-pi-A-Type Triazatruxene-Based Dopant-Free Hole Transporting Materials for Efficient and Stable Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Hiroyuki Kanda, Sanghyun Paek, Kasparas Rakstys, Cristina Roldán Carmona, Hobeom Kim, Cansu Igci

Three donor-pi-bridge-acceptor (D-pi-A)-type organic small molecules coded CI-B1, CI-B2, and CI-B3 are designed, synthesized, and used as dopant-free hole transporting materials (HTMs) for perovskite solar cells (PSCs). The strong electron-donating triazat ...

WILEY-V C H VERLAG GMBH2020

Branched Fluorenylidene Derivatives with Low Ionization Potentials as Hole-Transporting Materials for Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Kasparas Rakstys, Jianxing Xia

A group of small-molecule hole-transporting materials(HTMs) thatare based on fluorenylidene fragments were synthesized and testedin perovskite solar cells (PSCs). The investigated compounds weresynthesized by a facile two-step synthesis, and their properti ...

AMER CHEMICAL SOC2023

Passivating Defects of Perovskite Solar Cells with Functional Donor-Acceptor-Donor Type Hole Transporting Materials

Mohammad Khaja Nazeeruddin, Yi Zhang, Kasparas Rakstys, Jianxing Xia

In this study, a series of donor-acceptor-donor (D-A-D) type small molecules based on the fluorene and diphenylethenyl enamine units, which are distinguished by different acceptors, as holetransporting materials (HTMs) for perovskite solar cells is present ...

WILEY-V C H VERLAG GMBH2023

Efficiency vs. stability: dopant-free hole transporting materials towards stabilized perovskite solar cells

Mohammad Khaja Nazeeruddin, Kasparas Rakstys, Cansu Igci

In the last decade, perovskite solar cells have been considered a promising and burgeoning technology for solar energy conversion with a power conversion efficiency currently exceeding 24%. However, although perovskite solar cells have achieved high power ...

ROYAL SOC CHEMISTRY2019

Carbazole-Terminated Isomeric Hole-Transporting Materials for Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Hiroyuki Kanda, Sanghyun Paek, Kasparas Rakstys

A set of novel hole-transporting materials (HTMs) based on pi-extension through carbazole units was designed and synthesized via a facile synthetic procedure. The impact of isomeric structural linking on their optical, thermal, electrophysical, and photovo ...

AMER CHEMICAL SOC2020

Diketopyrrolopyrrole-based sensitizers for dye-sensitized solar cell applications: anchor engineering

Michael Graetzel, Jun Ho Yum, Kasparas Rakstys, Thomas Wesley Holcombe

A series of donor-chromophore-anchor (D-C-A) sensitizers comprising the diketopyrrolopyrrole (DPP) chromophore were synthesized and tested in both I-3(-)/I- and Co(bpy) redox shuttle DSC devices. The dye series was strategically designed to elucid ...

Royal Society of Chemistry2013