Byungha Shin

ABSTRACT Using vacuum process, we fabricated Cu 2 ZnSnS 4 solar cells with 8.4% efficiency, a number independently certified by an external, accredited laboratory. This is the highest efficiency reported for pure sulfide Cu 2 ZnSnS 4 prepared by any method. Consistent with literature, the optimal composition is Cu‐poor and Zn‐rich despite the precipitation of secondary phases (e.g., ZnS). Despite a very thin absorber thickness (~600 nm), a reasonably good short‐circuit current was obtained. Time

peer reviewed

The Material properties of BiVO₄ are modified <italic>via</italic> coupling with a SnO₂ buffer layer inserted between BiVO₄ and a FTO substrate.

Using in situ electrical biasing transmission electron microscopy, structural and chemical modification to n-i-p-type MAPbI₃ solar cells are examined with a TiO₂ electron-transporting layer caused by bias in the absence of other stimuli known to affect the physical integrity of MAPbI₃ such as moisture, oxygen, light, and thermal stress. Electron energy loss spectroscopy (EELS) measurements reveal that oxygen ions are released from the TiO₂ and migrate

We have studied the temperature dependent kinetics of MoSe2 formation between molybdenum and Cu2ZnSnSe4 (CZTSe) films during annealing in the presence of Se. CZTSe is an emerging light-absorbing material for thin film solar cell applications, and thermal treatment of this layer constitutes a critical part of the device processing. The formation of MoSe2 in this system is modeled using a three step mechanism—diffusion of Se through CZTSe, diffusion of Se through MoSe2, and reaction between Se and

The role of Cl in halide hybrid perovskites CH₃NH₃PbI₃(Cl) (MAPbI₃(Cl)) on the augmentation of grain size is still unclear although many reports have referred to these phenomena. Herein, we synthesized MAPbI₃(Cl) perovskite films by using excess MACl-containing precursors, which exhibited approximately an order of magnitude larger grain size with higher <110>-preferred orientation compared with that from stoichiometric precursors. Comprehens

The solution process is the most widely used method to prepare perovskite absorbers for high performance solar cells due to its ease for fabrication and low capital cost. However, an insufficient level of reproducibility of the solution process is often a concern. Complex precursor solution chemistry is likely one of the main reasons for the reproducibility issue. Here we report the effects of triple cation lead mixed-halide perovskite precursor solution aging on the quality of the resulting fil

Abstract The photoelectrochemical (PEC) properties of a Cu(In,Ga)Se 2 (CIGS) photocathode covered with reduced graphene oxide (rGO) as a catalyst binder for solar‐driven hydrogen evolution are reported. Chemically reduced rGO with various concentrations is deposited as an adhesive interlayer between CIGS/CdS and Pt. PEC characteristics of the CIGS/CdS/rGO/Pt are improved compared to the photocathode without rGO due to enhancement of charge transfer via efficient lateral distribution of photogene

Heavy-alkali post-deposition treatments (PDTs) utilizing Cs or Rb has become an indispensable step in producing high-performance Cu(In,Ga)Se₂ (CIGS) solar cells. However, full understanding of the mechanism behind the improvements of device performance by heavy-alkali treatments, particularly in terms of potential modification of defect characteristics, has not been reached yet. Here, we present an extensive study on the effects of CsF-PDT on material properties of CIGS absorbers and

Abstract Herein, solution‐processible inorganic hole‐transport layer (HTL) of a perovskite solar cell that consists of CuGaO 2 nanoparticles and CuSCN, which leads to an improved device performance as well as long‐term stability, is reported. Uniform films of CuGaO 2 are prepared by first treating CuGaO 2 nanoparticles with aminosilane that leads to well‐dispersed CuGaO 2 solution, followed by spin‐coating of the suspension. Subsequent spin‐coating of CuSCN solution onto the CuGaO 2 forms a smoo

Because of its excellent optical properties and good stability, all-inorganic halide perovskite CsPbX₃ (X = I, Br, Cl) has been attracting interest for use in light-emitting diodes (LEDs). One challenge is improving the efficacy of the spatial confinement of excitons for higher luminescence efficiency. Here, we present a simple yet very effective strategy to form fine-grain-structured CsPbBr₃ polycrystalline films prepared by thermal co-evaporation. The strategy involves co

Inorganic zero-dimensional perovskites, such as Cs4PbBr6, offer an underexplored opportunity to achieve efficient exciton formation and radiative recombination. In particular, the origin of sub-bandgap green emission from Cs4PbBr6 is not well understood. Herein, we develop a sequential deposition approach to growing highly smooth Cs4PbBr6 films with low rms roughness of 8.15 nm by thermal evaporation. We find that the films have an excitonic absorption edge at 3.9 eV, but exhibit sub-bandgap pho