Kayunkid, Navaphun

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Kayunkid, Navaphun
Alternative Name
Kayunkid, N.
Kayunkid, Nawapun
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Email
navaphun.ka@kmitl.ac.th

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    Enhancing Perovskite Thin Films with Butylammonium Iodide-Lead-Tetrahydrofuran: Surface Healing and 2D Formation in Annealing-Free Single-Crystal Films for Solar Cell Applications
    (2024-04-01)
    Azad, Farhad
    ;
    Supasai, Thidarat
    ;
    Yaro, Annafi Ado
    ;
    Soe, Kay Thi
    ;
    Thongprong, Non
    We demonstrate a functional method to achieve surface passivation and construct a two-dimensional (2D) layer on a three-dimensional (3D) perovskite, eliminating the need for subsequent annealing steps. A key process is the integration of a single methylammonium lead iodide (MAPbI<inf>3</inf>) crystal with butylammonium iodide (BAI) in tetrahydrofuran. Density functional theory calculations reveal that the synergy between BA<sup>+</sup> cations and Pb-I octahedral structures enables the formation of a distinct 2D layered framework. MA<sup>+</sup> and BA<sup>+</sup> exhibit adsorption energies of −5.519 and −5.925 eV, respectively, at MA vacancies on the perovskite surface. This finding indicates that BAI passivation induces surface-healing effects, increasing surface and device stability. The I<sup>-</sup> components of BAI also replace imperfections at the perovskite interface, affording considerably reduced deep-level anomalies and mitigating nonradiative recombination. This theoretical perspective is supported experimentally via X-ray photoelectron spectroscopy and glow discharge optical emission spectroscopy. BAI passivation and 2D-BA<inf>2</inf>PbI<inf>4</inf> capping lowers work functions for 3D perovskite surfaces, registering at approximately 0.158 and 0.173 eV, respectively, which are lower than those of the control 3D film. Within the 2D/3D perovskite configuration, 2D-BA<inf>2</inf>PbI<inf>4</inf> capping considerably increases the open-circuit voltage in solar cells. In comparison, devices with BAI-enhanced interfaces show improved durability with promise for solar cell applications.
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    Impact of a Spun-Cast MoOxLayer on the Enhanced Moisture Stability and Performance-Limiting Behaviors of Perovskite Solar Cells
    (2021-04-26)
    Rosungnern, Unyamanee
    ;
    Kumnorkaew, Pisist
    ;
    Kayunkid, Navaphun
    ;
    Chanlek, Narong
    ;
    Li, Youyong
    Organic-inorganic perovskite solar cells (PSCs), which have good environmental durability, are of great interest for practical applications. In this work, we show that a solution-processed MoOx layer acts as a buffer layer against high moisture stress to suppress defects in the perovskite and as a hole transport layer. The inversion of the photoinduced charge migration behaviors, that is, the electron preferentially moving toward the surface when MoOx is directly deposited onto the perovskite, is found to cause a significant loss in device functionality. The deposition of MoOx onto spiro-OMeTAD results in a lower photocurrent density-voltage (J-V) hysteresis behavior, a greatly enhanced electrical conductivity, and a significantly stabilized power conversion efficiency (PCE) when compared with those of devices without the MoOx layer. More importantly, the PCEs of the MoOx-based devices are retained at over 85% of their initial value, while only 75% is retained for a reference cell. This work highlights the facial fabrication approach of the solution-based MoOx layer and provides experimental evidence of the photogenerated charge migration behaviors on the perovskite/MoOx interface. This information would be beneficial for the further design and development of PSC technology.
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    Cesium Moderation and Structural Transformation on α-CsPbI2Br Perovskite Durability via Cation Retarding Migration: A Combined Simulation and Experimental Study
    (2025-03-01)
    Henjongchom, Nakorn
    ;
    Ruengsrisang, Waranchit
    ;
    Soe, Kay Thi
    ;
    Kayunkid, Navaphun
    ;
    Thongprong, Non
    Preliminary density functional theory studies suggest that cesium-ion (Cs<sup>+</sup>) migration possesses a low energy barrier at defective surfaces, which potentially induces lattice distortion of α-CsPbI<inf>2</inf>Br perovskites. Herein, we introduced surface design via mixed-cation and mixed-halide methods to enhance the durability and functionality of all-inorganic CsPbI<inf>2</inf>Br solar cells. The adsorption and adhesion energies indicate that formamidinium bromide (FABr) passivation creates a nonbonding surface with resistance to water molecules and induces lattice reconstruction at the surface into a cubic-like structure. Experimental validation in solar cell applications reveals that nonencapsulated formamidinium bromide − based devices can retain 84 % of the initial efficiency (13.29 %) after 336 h of use with 40 %–43 % of relative humidity, outperforming the reference cell that retained 20 % of the original efficiency (10.31 %) after 144 h. This findings highlight the dual role of FABr passivation in stabilizing the surface and reorganizing the lattice structure, contributing to significantly enhanced durability and performance CsPbI<inf>2</inf>Br solar cells.