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NiO Nanoparticle-Modified PTAA Hole Transport Layers for High-Efficiency and Stable Large-Area Perovskite Solar Cells
(2026-06-22)
Sukgorn, Nuttaya
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Kaewprajak, Anusit
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Lapawae, Komsun
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Sinthiptharakoon, Kitiphat
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Treetong, Alongkot
The hole transport layer (HTL) plays a central role in governing charge extraction, efficiency, and long-term stability in perovskite solar cells (PSCs). Although poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) is widely used as an organic HTL, its limited hole mobility and thermal robustness restrict device durability and scalability. Here, we report a hybrid organic−inorganic HTL formed by incorporating NiO nanoparticles into PTAA to simultaneously improve charge transport and thermal stability. Comprehensive spectroscopic and electrical analyses reveal that NiO incorporation deepens the valence band position, enhances hole mobility, accelerates interfacial hole extraction, and suppresses carrier recombination in PTAA:NiO films. As a result, planar n−i−p PSCs employing PTAA:NiO (10 mg mL−1) achieve a champion power conversion efficiency (PCE) of 20.76%, outperforming pristine PTAA-based devices (19.50%) while retaining 86.5% of their initial efficiency after 6000 h under ISOS-D-1 storage conditions. Importantly, NiO incorporation also improves module-level robustness by mitigating thermally induced interfacial degradation during high-temperature encapsulation. Scalable 10 × 10 cm2 minimodules deliver a PCE of up to 14.18% and retain 85.1% of their initial performance after 5000 h. Furthermore, integrated minimodules successfully powered a standalone PM2.5 monitoring system under indoor illumination, highlighting the practical potential of hybrid-HTL PSCs for durable large-area photovoltaic and low-power Internet-of-Things applications.
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Characterization of Bi-doped FAPbI3 perovskite films investigated by X-ray absorption spectroscopy
(2025-12-01)
Wechprasit, Tirapat
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Bootchanont, Atipong
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Infahsaeng, Yingyot
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Wongjom, Poramed
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Wannapaiboon, Suttipong
A thorough investigation of perovskite structures formed through doping is essential for advancing the efficiency and stability of perovskite solar cells. In this study, Bi-doped FAPbI<inf>3</inf> perovskite films with varying Bi concentrations (0.5–2%) were fabricated using a spin-coating technique on ITO glass substrates. Then the films’ phase structure, local structure, and optical characteristics were analyzed. X-ray diffraction (XRD) analysis revealed that the pristine FAPbI<inf>3</inf> film exhibited both hexagonal and cubic phases, indicating structural instability. In contrast, Bi-doped FAPbI<inf>3</inf> films predominantly displayed a cubic perovskite structure, with a notable reduction in the XRD peak intensity corresponding to the hexagonal phase. UV–Vis spectroscopy showed that the undoped FAPbI<inf>3</inf> film had an absorption edge in the visible-near infrared range, while Bi-doping caused a redshift, indicating a reduction in the optical band gap. The calculated results show that optical band gaps decrease with increasing Bi, from a value of 1.49 (pure) to 1.43 (2% Bi) eV. X-ray absorption near edge structure (XANES) analysis confirmed the oxidation states of Pb2+ and Bi3+ ions across all samples, with Bi ions replacing Pb in the local structure. Photoluminescence (PL) measurements revealed an increased PL intensity with 1% Bi doping (7 105) compared with pristine FAPbI<inf>3</inf> (4.7 105), suggesting a reduction in carrier recombination. These findings demonstrate the potential of Bi-doping to stabilize perovskite structures with improved optoelectronic properties.
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The influence of palladium doping on the structural, morphological, optical and electronic properties of formamidinium lead iodide perovskite films
(2025-12-01)
Wechprasit, Tirapat
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Bootchanont, Atipong
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Infahsaeng, Yingyot
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Wongjom, Poramed
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Wannapaiboon, Suttipong
In this study, we investigated the effects of palladium (Pd) doping on the properties of formamidinium lead iodide (FAPbI<inf>3</inf>) perovskite films. Pd was doped at concentrations ranging from 0.5 to 2 % and coated onto indium tin oxide (ITO) glass substrates using a spin-coating technique. The crystal structure of the films was characterized using X-ray diffraction (XRD), revealing that Pd-doping reduces the hexagonal phase while increasing the cubic phase in the FAPbI<inf>3</inf> lattice. The optical properties were evaluated using ultraviolet–visible spectrophotometry (UV–Vis), showing changes in light absorption and a reduction in the energy gap with Pd incorporation. Scanning electron microscopy (SEM) was employed to examine the morphological properties of the films, indicating significant surface alterations and formation of larger grain sizes due to Pd incorporation. The electronic structure of perovskite films was thoroughly investigated using X-ray photoelectron spectroscopy (XPS). These findings demonstrate that Pd-doping significantly affects the structural, optical, and electronic properties of FAPbI<inf>3</inf> perovskite films, with potential implications for enhancing the performance of perovskite-based devices.
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Simultaneous Improvement in Photovoltaic Performance and Air Stability of Perovskite Solar Cells by Controlling Molecular Orientation of Spiro-OMeTAD
(2024-07-22)
Sukgorn, Nuttaya
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Kaewprajak, Anusit
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Rodbuntum, Sasiphapa
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Kayunkid, Navaphun
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Rujisamphan, Nopporn
2,2′,7,7′-Tetrakis (N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene (Spiro-OMeTAD) is a prototypical hole transport layer (HTL) for high-performance perovskite solar cells (PSCs). Since the electric conductivity of a neat Spiro-OMeTAD film is low, the HTL is generally doped with additives to increase charge density and mobility. However, the doped Spiro-OMeTAD film suffers from moisture absorption, which deteriorates the long-term stability of PSCs. This work reports that the molecular orientation of Spiro-OMeTAD molecules in the doped HTL is vital to solving this issue. Templating the molecular arrangement of Spiro-OMeTAD by a solidifying solvent, 1,3,5-trichlorobenzene (135-TCB), forms an anisotropic film of the doped Spiro-OMeTAD and induces a face-on orientation along the surface normal. Modifying the molecular orientation enhances hole mobility in the HTL and extraction of holes at the perovskite/HTL interface. As a result, the maximum power conversion efficiency (PCE) of the PSCs increases from 17.63 to 19.92%. Besides, the air stability of the PSCs with the face-on Spiro-OMeTAD, after storage for 1000 h, is superior to that of the devices without templating the molecular arrangement of Spiro-OMeTAD by 135-TCB. Control of the molecular orientation of Spiro-OMeTAD is critical for improving PCE and air stability.
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WO3:AgInS2 quantum dot electron transport layers in enhanced perovskite solar cells
(2023-04-14)
Seriwattanachai, Chaowaphat
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Kaewprajak, Anusit
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Sukgorn, Nuttaya
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Kumnorkaew, Pisist
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Nukeaw, Jiti
The development of the electron transport layers (ETL) was crucially important for the improvement of charge extraction and transportation in perovskite solar cells (PSCs). Here, dual electron transport layers of TiO<inf>2</inf> and WO<inf>3</inf> mixed with different sizes of AgInS<inf>2</inf> quantum dots (TiO<inf>2</inf>/WO<inf>3</inf>:AgInS<inf>2</inf> QDs) were fabricated for planar perovskite solar cells. The peak intensity of the photoluminescence (PL) of the synthesized AgInS<inf>2</inf> QDs were redshifted from 554 to 655 nm with an increased radius of AgInS<inf>2</inf> QDs from 3.82 ± 0.52 to 7.78 ± 1.37 nm. The PL intensity of the perovskite film on TiO<inf>2</inf>/WO<inf>3</inf>:AgInS<inf>2</inf> QDs was quenched by the addition of AgInS<inf>2</inf> QDs. The improved device stability was probably caused by the WO<inf>3</inf>:AgInS<inf>2</inf> QDs layer protecting the interface of perovskite layers from direct contact with TiO<inf>2</inf> to prevent UV decomposing. Therefore, the TiO<inf>2</inf>/WO<inf>3</inf>:AgInS<inf>2</inf> QDs as electron transport layers promoted the perovskite solar cell performance and enhanced the long-term stability. Graphical abstract: [Figure not available: see fulltext.].
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Unveiling the Influence of the Spectral Irradiance of Indoor Light-Emitting Diodes on the Photovoltaics of a Methylammonium Lead Iodide-Based Device
(2022-01-01)
Supasai, Thidarat
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Soe, Kay Thi
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Smerchit, Thapanut
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Azad, Farhad
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Thongprong, Non
An understanding of the spectrum–property relationship of perovskite solar cells when illuminated by light-emitting diodes that are used for indoor applications is necessary. Herein, it is aimed to explore the influences of correlated-color temperatures on a MAPbI<inf>3</inf>-based device under low-light conditions. Given an irradiance of approximately 3 W m−2 (or ≈1000 lx), a maximum free carrier generation rate of 1.0 × 1021 m−3 s−1 was found. Additionally, power conversion efficiencies (PCEs) up to 31.97%, 30.36%, and 28.98% with maximum power outputs of 13.66, 13.02, and 16.09 μW could be reached at 3000, 4000, and 6500 K, respectively. Additional increases in the PCEs were observed when high-energy blue light (in a range of 400–550 nm) was excluded during the current–voltage sweeps. In combination with the surface photovoltage measurements, intense blue light (under 6500 K) had a minimal influence on the photoinduced charge separation signals when compared to those caused by 3000 and 4000 K light. As a solar cell, the PCE reached as high as 34.52%, which corresponded to 73.08% of the thermodynamic limit of its bandgap at 3000 K.
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An unconventional blade coating for low-cost fabrication of PCDTBT: PC70BM polymer and CH3NH3PbIxCl3-x perovskite solar cells
(2021-04-01)
Kaewprajak, Anusit
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Kumnorkaew, Pisist
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Lohawet, Khathawut
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Duong, Binh
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Chonsut, Teantong
A low-cost and unconventional blade coating technique, called convective deposition, has been introduced for PCDTBT:PC<inf>70</inf>BM polymer and CH<inf>3</inf>NH<inf>3</inf>PbI<inf>x</inf>Cl<inf>3-x</inf> perovskite solar cell fabrication. With the new technique, only 10–20 microliter droplets per one square inch substrate were used to deposit hole transporting material, as well as photoactive and electron transporting materials, sequentially to create a p-i-n structure solar cell. Thin film deposition and solar cell fabrication from the standard spin coating and the convective deposition were compared. Smaller and better distribution of PC<inf>70</inf>BM domain in the PCDTBT:PC<inf>70</inf>BM film was observed in the film prepared by the convective deposition. Unlike the conventional doctor-blade coating or the spin coating, the film thickness can simply be adjusted by the convective deposition speed. The highest averaged power conversion efficiency (PCE) of 6.34% was obtained from the polymer solar cell prepared by the convective deposition at the coating speed of 750 μm/s compared to 5.60% PCE from the spin coating at the speed of 2500 rpm. For perovskite solar cell, a heating stage was used during the convective deposition of perovskite ink, 10.61% PCE was achieved with the stage temperature of 70 °C and the 2500 μm/s deposition speed. Layer-by-layer deposition with the convective deposition used in this study offers benefits over the standard spin coating by reducing amount of material consumption in the fabrication process and being suitable for low-cost fabrication of other solution-based optoelectronic devices.
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Pedot:Pss film preparation and characterization using convective deposition system controlled by arduino microcontroller for organic photovoltaic application
(2021-01-01)
Wongrerkdee, Sawitree
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Ritruksa, Mantarat
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Phattum, Saisunee
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Lohawet, Khathawut
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Kaewprajak, Anusit
PEDOT:PSS films are prepared using convective deposition system. The convective deposition system is designed and controlled by a low-cost Arduino microcontroller. The microcontroller shows suitable potential for the system operation with good performance. Then, the system was applied to prepare PEDOT:PSS films and the prepared films are characterized. The prepared films reveal the increase in roughness and thickness for the high-velocity operation which could be occurred due to turbulent flows of PEDOT:PSS molecules. The result causes a decrease in transmittance, resistance, and water contact angle. For organic photovoltaic application, the enhanced power conversion efficiency is observed in corresponding to the increased short-circuit current density due to carrier transport efficiency improvement in organic photovoltaic devices provided by rough surfaces and thick films. The success of organic photovoltaic fabrication confirms the accepting ability of the convective deposition system controlled by Arduino microcontroller for non-vacuum thin film deposition. Thus, it should be considered as a usefulness system for thin-film based device fabrication with a low-cost operation.
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Surface modification of PEDOT: PSS film by chemical vapor texturing process for enhanced organic photovoltaics
(2020-12-01)
Ritruksa, Mantarat
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Wongrerkdee, Sawitree
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Lohawet, Khathawut
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Kaewprajak, Anusit
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Kumnorkaew, Pisist
Surface modification of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) film was performed using chemical vapor texturing process of HNO<inf>3</inf> vapor. Textured PEDOT:PSS film exhibits higher root-mean-square roughness of 14.43 nm than pristine PEDOT:PSS film of 11.87 nm with small decrease in thickness. Moreover, approximate one-half reduction of sheet resistance is measured. In correspondence with roughness, increasing optical transmittance in the visible region and reducing water contact angle are explored. The reduction of water contact angle implies that active layer can be deposited on the textured film with better coverage to improve interfacial contact for OPV fabricating process. This improvement facilitates charge transfer in OPV device which causes the increase of short-circuit current density (J<inf>sc</inf>) from 7.42 mA/cm2 to 8.01 mA/cm2. The increased J<inf>sc</inf> is the major photovoltaic parameter in OPV enhancement. Therefore, the PEDOT:PSS film textured with the chemical vapor texturing process is demonstrated as an efficient rough film for OPV enhancement. Furthermore, the rough film modified using the process could be suggested for applying in several thin-film based devices.
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Enhanced performance of bulk heterojunction solar cells using double layers deposition of polymer:fullerene derivatives
(2015-06-23)
Khantha, Chanitpa
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Chonsut, Teantong
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Kaewprajak, Anusit
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Kumnorkaew, Pisist
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Wootthikanokkhan, Jatuphorn
Poly[4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene-co-quinoxaline] (PBDTQx) copolymer; to be used as an electron donor in bulk heterojunction (BHJ) polymer solar cell; was synthesized from benzo[1,2-b:4,5-b′]dithiophene and quinoxaline via a Stille coupling reaction. BHJ polymer solar cells based on the ternary blend of PBDTQx; indene-C<inf>60</inf> bisadduct (ICBA) and [6,6]-phenyl-C<inf>71</inf>-butyric-acid-methyl-ester(PC<inf>71</inf>BM) were then fabricated and tested for the power conversion efficiency (PCE) values. From the IV curves; it was found that the open circuit voltage (V<inf>oc</inf>) and current density (J<inf>sc</inf>) of the solar cell increased with the addition of ICBA. This was related to the lowest unoccupied molecular orbital (LUMO) level of ICBA; which is suitable with those of PC<inf>71</inf>BM and PBDTQx. It was also found that PCE of the solar cell can be improved significantly by double layers coating of the active materials (PBDTQx:PC<inf>71</inf>BM:ICBA). The above effect was ascribed to changes in morphology and crystallinity of the active layer.

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