🎉 Congratulations to our five Master’s students, who successfully passed their thesis defenses under the supervision of Prof. Cheng-Ying (Gary) Chen!
Their thesis titles are as follows:

1. Hung-Yu Chen
   Enhancing Photoelectrochemical Hydrogen Production and Related Applications Using Sb₂(S,Se)₃ Thin Films Synthesized via Hydrothermal Method with Post-Annealing Optimization

2. Yu-Hsiang Tsai
   Fabrication of Cuprous Oxide Semiconductor Thin Films by Reactive Sputtering for Photoelectrochemical Water Splitting Applications

3. Tsan-Hsuan Yang
   Antimony-Doped Cuprous Oxide Thin Films Grown by Chemical Bath Deposition for Photoelectrochemical Water Splitting Applications

4. Juan-Xuan Li
   Preparation of Gallium-Doped Cuprous Oxide Semiconductor Films via Sputtering for Photoelectrochemical Water Splitting Applications

5. Ching-Yung Tseng

Atom Probe Study on Gallium-Doped Cuprous Oxide Thin Film 

🎉 Congratulations to Mr. Yuan-Chi Lin, graduate student of our lab, for receiving the NSTC Graduate Student Travel Grant to attend the International Conference on Materials for Advanced Technologies (ICMAT 2025) in Singapore, and for delivering an oral presentation! 👏

📄 Presentation Title:
Sb₂(S,Se)₃ Thin Films Synthesized by Hydrothermal Method for Photoelectrochemical Water Splitting and Solar Cell Applications

🗓 Conference Date: June 30 – July 4, 2025
📍 Venue: Suntec Convention Centre, Singapore

🎉 Congratulations to Prof. Cheng-Ying (Gary) Chen for being recognized as an Elsevier Reviewer for the first half of 2025!

This honor highlights his valuable contributions to the peer-review process and academic service in the Elsevier publishing community. 👏 

🎉 Congratulations to Prof. Cheng-Ying (Gary) Chen and his graduate student Yu-Hsiang Tsai, who received the Best Poster Award in the category of Novel Material Characterization and Analysis Techniques at the 5th Symposium on Nano Devices, Circuits, and Technology (SNDCT 2025)! 👏 (May 28, 2025 )

🎉 Congratulations to Prof. Cheng-Ying (Gary) Chen for the Invited Talk at NTU Physics

Prof. Cheng-Ying (Gary) Chen was invited to give a talk at the Department of Physics, National Taiwan University on the topic:
“Advancing Kesterite-Based Solar Cells: Structural, Defect, and Interface Engineering Strategies for Enhanced Efficiency.”
The seminar will be held on April 23, 2025 (Wednesday) at 2:20 PM, in Rm. 104, Chin-Pao Yang Lecture Hall, NTU Physics.

This talk will highlight our group’s recent advances in kesterite-based thin-film solar cells (CZTSSe), with a focus on structural control, defect engineering, and interface design to overcome voltage deficits and enhance photovoltaic performance.

🎉 Congratulations to our lab for the successful publication in ACS Applied Materials & Interfaces!
📄 Title: Ultrathin Bi₂O₂Se/Si Heterojunction Photodetector with Tunneling Oxide Passivation for Enhanced Optoelectronic Performance 

ACS Appl. Mater. Interfaces 2025, 17, 18, 26931–26939 https://doi.org/10.1021/acsami.5c03477 

This work reports a high-performance Bi₂O₂Se/Si heterojunction photodetector fabricated by a transfer-free pulsed laser deposition approach, integrated with a thin tunneling SiO₂ passivation layer. The device demonstrates ultralow dark current (~22.3 nA/cm²), high on/off ratio (~8 × 10⁶), and remarkable responsivity (23.0 A/W) under zero bias, together with sub-millisecond response time. These results highlight Bi₂O₂Se’s great potential for next-generation optoelectronic and photonic applications.  (November 15, 2024) 

🏆✨ Excited to share that Prof. Cheng-Ying (Gary) Chen’s paper
“Visualizing Vacancy Annihilation in CZTSe Solar Cells by Hydrogen-Assisted Selenization with In Operando X-ray Nanoprobe Studies”
presented at the 2025 Materials Research Society (MRS) Spring Meeting, Symposium EN05: Thin-Film Compound Semiconductor Photovoltaics (Seattle, USA), has been selected as a finalist for the Best Paper Award (CONTROL ID: 4207310).

This recognition highlights his team’s cutting-edge research on anion vacancy defect elimination in CZTSe solar cells through advanced in-operando X-ray nanoprobe analysis. 👏

📢 Congratulations to Prof. Cheng-Ying (Gary) Chen for being recognized as an ACS Reviewer for 2024!  This honor highlights his valuable contributions to the peer-review process and academic service in the ACS publishing community. 👏 

🎉 Congratulations to our group member Hong-Yu Chen for receiving the NSTC Graduate Student Travel Grant to attend LASE 2025 (SPIE Conference) in San Francisco, USA, and deliver an oral presentation! 👏

📄 Paper Title:
Optical properties of hydrothermally synthesized Sb₂(S,Se)₃ and their application in water splitting

📚 Proceedings: Volume PC13352, Nanoscale and Quantum Materials: From Synthesis and Laser Processing to Applications 2025; Paper No. PC1335201 (2025)
🔗 DOI: 10.1117/12.3042515

📢 Congratulations to Prof. Cheng-Ying (Gary) Chen and his graduate student Yu-Hsiang Tsai, for receiving the Student Poster Paper Award at OPTIC 2024!  (November 29, 2024) 

📢 Congratulations to our lab for the successful publication in ACS Applied Materials & Interfaces!
📄 Title: Visualization of Anion Vacancy Defect Annihilation in CZTSe Solar Cells by Hydrogen-Assisted Selenization with In Operando X-ray Nanoprobe Studies 

ACS Appl. Mater. Interfaces 2024, 16, 47, 64656–64663 https://doi.org/10.1021/acsami.4c11127  

This work demonstrates how hydrogen-assisted selenization (HAS) effectively reduces selenium vacancies in CZTSe thin-film solar cells, leading to enhanced photocurrent and improved device efficiency (up to 10.36%). Using synchrotron-based nano-XRF and nano-XBIC, we directly visualized the correlation between defect annihilation and charge collection, providing new insights into defect engineering for next-generation kesterite photovoltaics. (November 15, 2024) 

📢 Congratulations to Ching-Yung Tseng and Yu-Hsiang Tsai from our lab for winning the Poster Excellent Award in the category Optoelectronic and Optical Materials at the 2024 Annual Meeting of the Materials Research Society-Taiwan (MRST 2024)! 👏

📑 Ching-Yung Tseng — Atom Probe Study on the Atomic Distribution of Sb/Ga-Doped Cu₂O Thin Films
📑 Yu-Hsiang Tsai — Reactive Sputtering Fabrication of Cu₂O Thin Films for Photoelectrochemical Water Splitting

This award recognizes their outstanding contributions to research in materials science and optoelectronics. (November 1, 2024) 

📢 Congratulations to Prof. Cheng-Ying (Gary) Chen for receiving the 11th Young Scholar Award of the Taiwan Vacuum Society (TVS)(October 28, 2022)! 

This award recognizes his outstanding contributions to semiconductor thin films, defect/interface engineering, and advanced characterization for energy and optoelectronic applications. 

🎉 Congratulations to our lab for the publication in Sustainability (IF 3.9, 2022)!
📄 Title: Back Contact Engineering to Improve CZTSSe Solar Cell Performance by Inserting MoO₃ Sacrificial Nanolayers 

Sustainability 2022, 14(15), 9511; https://doi.org/10.3390/su14159511 

This study introduces an ultrathin MoO₃ sacrificial nanolayer to optimize the Mo/CZTSSe back-contact interface in thin-film solar cells. The MoO₃ layer promotes grain growth, suppresses harmful MoS(e)₂ formation, and improves absorber quality. Key results include:

• Defect energy level reduced from 228 meV to 148 meV

• Series resistance decreased from 1.83 Ω·cm² to 1.54 Ω·cm²

• Fill factor (FF) increased to 52.12%

• Efficiency improved by ~26%, achieving a maximum 7.78% PCE

First-principles (VASP) calculations further revealed that sulfoselenized MoO₃ nanolayers act as p-type hole-selective contacts, contributing to enhanced device performance. (August 3, 2022)