Publications by Yeonju Kim | EPFL Graph Search

Multifunctional sulfonium-based treatment for perovskite solar cells with less than 1% efficiency loss over 4,500-h operational stability tests

Ulf Anders Hagfeldt, Bowen Yang, Yeonju Kim, Jiajia Suo

The stabilization of grain boundaries and surfaces of the perovskite layer is critical to extend the durability of perovskite solar cells. Here we introduced a sulfonium-based molecule, dimethylphenethylsulfonium iodide (DMPESI), for the post-deposition tr ...

Nature Portfolio2024

Methylammonium Nitrate-Mediated Crystal Growth and Defect Passivation in Lead Halide Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Jun Ho Yum, Kevin Sivula, Yeonju Kim

Additive engineering has been a crucial strategy to improve photovoltaic properties by reducing carrier trap centers or increasing carrier diffusion lengths in the lead halide perovskite active layer. We introduced a small amount of CH3NH3 +NO3 - (methylam ...

Amer Chemical Soc2024

Interfacial engineering through lead binding using crown ethers in perovskite solar cells

Jun Ho Yum, Kevin Sivula, Jiyoun Seo, Jovana Milic, Yeonju Kim

In the domain of perovskite solar cells (PSCs), the imperative to reconcile impressive photovoltaic performance with lead-related issue and environmental stability has driven innovative solutions. This study pioneers an approach that not only rectifies lea ...

Elsevier2024

Decoupling Interlayer Spacing and Cation Dipole on Exciton Binding Energy in Layered Halide Perovskites

Rosario Scopelliti, Nicolas Grandjean, Jun Ho Yum, Kevin Sivula, Simon Nussbaum, Han-Hee Cho, Yeonju Kim

Layered halide perovskites (LHPs) are emerging semiconductor materials due to their superior environmental stability compared to that of traditional halide perovskites. While LHPs have tunable optoelectronic properties, quantum and dielectric confinement e ...

2024

Carbazole Treated Waterproof Perovskite Films with Improved Solar Cell Performance

Michael Graetzel, Paul Joseph Dyson, Ursula Röthlisberger, Haizhou Lu, Felix Thomas Eickemeyer, Yeonju Kim, Jaeki Jeong, Lukas Pfeifer, Nikolaos Lempesis, Virginia Carnevali

Surface passivation has been widely employed to suppress non-radiative charge recombination and prevent interfacial charge accumulation in perovskite photovoltaics. In this report, carbazole modified with ammonium iodide connected via alkyl chains of diffe ...

Wiley-V C H Verlag Gmbh2024

Coordination modulated passivation for stable organic-inorganic perovskite solar cells

Ulf Anders Hagfeldt, Yeonju Kim, Jaeki Jeong

Despite the recent exceptional rise in power conversion efficiency of perovskite solar cells (PSCs), surface defects and ion migration related instability are still present in PSCs. The chain length and binding energy of the passivation material play impor ...

2023

Materials engineering for improved stability of perovskite solar cells

Yeonju Kim

Halide perovskites have gained tremendous attention over the past decade, but the poor stability of perovskite solar cells (PSCs) under operating conditions hampers their practical application. This thesis investigates materials that can be used to enhance ...

EPFL2023

Additives-free indolo[3,2-b]carbazole-based hole-transporting materials for perovskite solar cells with three yeses: Stability, efficiency, simplicity

Ulf Anders Hagfeldt, Bowen Yang, Yeonju Kim, Jiajia Suo

Indolo[3,2-b]carbazole-based hole transporting materials (HTM1-3) are developed for dopant-free pemvskite solar cells (PSCs). The newly synthesized compounds are studied as alternatives of conventional hole-transporting materials which typically require ad ...

Elsevier2022

Surface Reconstruction Engineering with Synergistic Effect of Mixed‐Salt Passivation Treatment toward Efficient and Stable Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Filippo de Angelis, Hui-Seon Kim, Bowen Yang, Yeonju Kim, Jiajia Suo

Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well a ...

2021

When photoluminescence, electroluminescence, and open-circuit voltage diverge - light soaking and halide segregation in perovskite solar cells

Ulf Anders Hagfeldt, Wolfgang Richard Tress, Bowen Yang, Yeonju Kim

Perovskite solar cells suffer from various instabilities on all time scales. Some of them are driven by light, in particular when employing compounds with mixed halides. Such light soaking effects have been observed to result in performance changes of sola ...

Royal Society of Chemistry2021

Interfacial Passivation Engineering of Perovskite Solar Cells with Fill Factor over 82% and Outstanding Operational Stability on n-i-p Architecture

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ulf Anders Hagfeldt, Bowen Yang, Yeonju Kim, Jiajia Suo

Tremendous efforts have been dedicated toward minimizing the open-circuit voltage deficits on perovskite solar cells (PSCs), and the fill factors are still relatively low. This hinders their further application in large scalable modules. Herein, we employ ...

AMER CHEMICAL SOC2021

Interfacial versus Bulk Properties of Hole-Transporting Materials for Perovskite Solar Cells: Isomeric Triphenylamine-Based Enamines versus Spiro-OMeTAD

Ulf Anders Hagfeldt, Bowen Yang, Yeonju Kim, Jiajia Suo

Here, we report on three new triphenylamine-based enamines synthesized by condensation of an appropriate primary amine with 2,2-diphenylacetaldehyde and characterized by experimental techniques and density functional theory (DFT) computations. Experimental ...

AMER CHEMICAL SOC2021