FY2022 Annual Report

Energy Materials and Surface Sciences Unit


Efficient energy harvesting, storage and utilization are among the most pressing concerns of the modern world. The need for renewable and sustainable energy is driving research into new materials and technologies that can provide efficient, cost-effective, and environmentally-friendly solutions. Halide perovskite materials are emerging as promising candidates in this quest. In this report, we summarize our recent progresses on the fundamental aspects of perovskite materials (Sections 3.1 and 3.2), perovskite solar cells and modules aiming at efficient solar energy conversion (Sections 3.3 and 3.4).  We also continued to develop alternative cost-effective up-scalable fabrication strategies of perovskite light-emitting diodes (LEDs, ~60 mm2) with green color emission (Section 3.5). An essential area of research in solar energy harvesting pertains to uninterrupted utilization of electricity derived from solar panels. The future utilization of non-intermittent solar energy harvesting-storage devices will be greatly influenced by the development of cost-effective and high-performance electrical energy storage systems (Section 3.6), including Li batteries and other related technologies, in combination with solar panels. 

1. Unit Members

• Ms. Naoko Ogura-Gayler, Research Unit Administrator
• Dr. Luis K. Ono, Group Leader
• Dr. Chenfeng Ding, Researcher
• Dr. Congyang Zhang, Researcher
• Dr. Tianhao Wu, Researcher
• Dr. Silvia Mariotti, Researcher
• Dr. Shuai Yuan, Researcher
• Dr. Penghui Ji, Researcher
• Dr. Tongtong Li, Researcher
• Mr. Jiahao Zhang, OIST Graduate Student
• Ms. Ilhem Nadia Rabehi, OIST Graduate Student
• Ms. Daria Sherstiukova, OIST Graduate Student (Rotation)
• Mr. Dmitry Kovaleskiy, OIST Graduate Student (Rotation)
• Mr. Hengyuan Wang, Visiting Research Student
• Mr. Caiyi Zhang, Visiting Research Student
• Ms. Xiaomin Liu, Visiting Research Student
• Ms. Xiaomin Huo, Visiting Research Student
• Mr. Ting Guo, Visiting Research Student
• Mr. Ryusei Morimoto, Research Intern
• Mr. Kaisei Furudate, Research Intern

2. Collaborations

  1. CsI enhanced buried interface for efficient and UV‐robust perovskite solar cells​ - Adv. Energy Mater. 12, 2103151 (2022).
    • Type of collaboration: collaborative research
    • Collaborators:
      • Prof. Yixin Zhao, Shanghai Jiao Tong University, China.
      • Prof. Taiyang Zhang, Shanghai Institute of Technology, China.
  2. Heterogeneous FASnI3 absorber with enhanced electric field for high‑performance lead‑free perovskite solar cells - Nano-Micro Lett​. 14, 99 (2022).
    • Type of collaboration: collaborative research
    • Collaborators:
      • Prof. Liyuan Han, Shanghai Jiao Tong University, China; University of Tokyo, Japan.
  3. Synergistic stabilization of CsPbI3 inorganic perovskite via 1D capping and secondary growth - J. Energy Chem. 68, 387-392 (2022).
    • Type of collaboration: collaborative research
    • Collaborators:
      • Prof. Yixin Zhao, Shanghai Jiao Tong University, China.
      • Prof. Yuetian Chen, Shanghai Jiao Tong University, China.
  4. Residual strain reduction leads to efficiency and operational stability improvements in flexible perovskite solar cells - Mater. Adv. 3, 6313 (2022).
    • Type of collaboration: collaborative research
    • Collaborators:
      • Prof. Longbin Qiu, Southern University of Science and Technology​, China.
  5. Robust hole transport material with interface anchors enhances the efficiency and stability of inverted formamidinium–cesium perovskite solar cells with a certified efficiency of 22.3% - Energy Environ. Sci. 15, 2567 (2022).
    • Type of collaboration: collaborative research
    • Collaborators:
      • Prof. Zonghao Liu, Huazhong University of Science and Technology​, Optics Valley Laboratory, China.
      • Prof. Wei Chen, Huazhong University of Science and Technology​, Optics Valley Laboratory, China.
  6. Grading patterning perovskite nanocrystal-polymer composite films for robust multilevel information encryption and decryption - Chem. Eng. J. 451, 138240 (2022).
    • Type of collaboration: collaborative research
    • Collaborators:
      • Prof. Jingbo Wu, Shanghai University, Zhejiang Laboratory, HKUST Shenzhen-Hong Kong Collaborative innovation Research institute, China.
  7. High-efficiency CsPbI2Br perovskite solar cells with over 83% fill factor by synergistic effects of a multifunctional additive - Inorg. Chem. 62, 5408-5414 (2023).
    • Type of collaboration: collaborative research
    • Collaborators:
      • Prof. Shufang Zhang, Ludong University, China.
      • Prof. Yanfeng Tang, Nantong University, China.

3. Activities and Findings

3.1 Surface science study on metal halide perovskites.

Jeremy Hieulle, Dae-Yong Son, Afshan Jamshaid, Xin Meng, Collin Stecker, Robin Ohmann, Zonghao Liu, Luis K. Ono, Yabing Qi*, "Metal Halide Perovskite Surfaces with Mixed A-Site Cations: Atomic Structure and Device Stability"  Adv. Funct. Mater.33, 2211097 (2023). [Published before March 31st, 2023 corresponding to the end of FY2022 in the Japanese calendar.]

Characterization of perovskites at the atomic scale helps to determine the underlying fundamental dynamics taking place within the perovskite material as well as during solar cell operation. In this study (Figure 1), the surface atomic structure of CsxMA1-xPbBr3 perovskite films grown on Au(111) using a dual-source evaporation under the ultrahigh vacuum conditions was characterized by scanning tunneling microscopy (STM). In addition, X-ray photoelectron spectroscopy, ultraviolet photoemission spectroscopy, and inverse photoemission spectroscopy were employed to study the stability and electronic properties of CsxMA1-xPbBr3. The partial substitution of MA+ by Cs+ induces a modification of the perovskite structure leading to improved structural stability.


Figure 1: Pristine and mixed cation perovskite surfaces visualized by low-temperature scanning tunneling microscopy images: (a) MAPbBr3, (b) CsxMA1−xPbBr3, and (c) CsPbBr3 perovskite surfaces.

3.2 Inorganic halide perovskite induced growth of lead silicate glass ring structure.

Guoqing Tong, Wentao Song, Luis K. Ono, Yabing Qi*, "From film to ring: Quasi-circular inorganic lead halide perovskite grain induced growth of uniform lead silicate glass ring structure" Appl. Phys. Lett.​​ 120, 161604 (2022). 

The unique characteristics and potential uses of microstructures, specifically nanowires (NWs) and microwires (MWs), as well as quantum dots, have garnered significant attention in research. Concomitantly, halide perovskites are receiving increasing academic/commercial interest due to their outstanding optoelectronic properties and high efficiency in solar cells and light-emitting diodes (LEDs). In this work (Figure 2), we showed that the polycrystalline properties of perovskites can induce the growth of different nanostructures. In particular, by employing inorganic CsPb2Br5 perovskite grains as templates, the formation of ring-like structures on a SiO2/Si substrate was induced.


Figure 2: Scanning electron microscope (SEM) images of the ring-like structures from CsPb2Br5 precursor film; atomic force microscopy (AFM) morphology images of the single ring-like structure.


3.3  Perovskite solar cells and modules with regular and inverted structure.

Tongle Bu, Luis K Ono, Jing Li, Jie Su, Guoqing Tong, Wei Zhang, Yuqiang Liu, Jiahao Zhang, Jingjing Chang, Said Kazaoui, Fuzhi Huang, Yi-Bing Cheng, Yabing Qi*, "Modulating crystal growth of formamidinium–caesium perovskites for over 200 cm2 photovoltaic sub-modules" Nat. Energy7, 528 (2022). 

Tianhao Wu, Luis K. Ono, Rengo Yoshioka, Chenfeng Ding, Congyang Zhang, Silvia Mariotti, Jiahao Zhang, Kirill Mitrofanov, Xiao Liu, Hiroshi Segawa, Ryota Kabe, Liyuan Han, Yabing Qi*, "Elimination of light-induced degradation at the nickel oxide-perovskite heterojunction by aprotic sulfonium layers towards long-term operationally stable inverted perovskite solar cells"  Energy Environ. Sci.15, 4612-4624 (2022).

Tianhao Wu, Xiushang Xu, Luis K Ono, Ting Guo, Silvia Mariotti, Chenfeng Ding, Shuai Yuan, Congyang Zhang, Jiahao Zhang, Kirill Mitrofanov, Qizheng Zhang, Saurav Raj, Xiao Liu, Hiroshi Segawa, Penghui Ji, Tongtong Li, Ryota Kabe, Liyuan Han, Akimitsu Narita*, Yabing Qi*, "Graphene‐Like Conjugated Molecule as Hole‐Selective Contact for Operationally Stable Inverted Perovskite Solar Cells and Modules"  Adv. Mater.​ 2300169 (2023).

For perovskite photovoltaic technology to be viable for commercial use, high efficiencies, upscaling, and long-term operational stability are prerequisites. In one of the studies (Figure 3a), we reported an efficient upscaling fabrication strategy for high-quality and stable FA–Cs perovskite films by the perovskite precursor ink engineering. Our strategy is based on the addition of CH3NH3Cl in the co-solvent system of dimethylformamide/N-methyl-2-pyrrolidone (DMF/NMP), which significantly lowers the formation energy and enlarges the crystal size of the FA–Cs perovskite films, contributing to the successful scalable deposition of large-area. Utilizing blade-coating technique, large-scale solar sub-modules achieved an efficiency of 15.3% with an aperture area of 205 cm2.

In another study (Figure 3b), we developed a hole-selective molecule with the benzo[rst]pentaphene (BPP) core and the methyl benzoate terminal groups that self-anchor on the ITO substrate (benzo[rst]pentaphene, SA-BPP) for operationally stable inverted perovskite solar cells and modules. SA-BPP is compatible with upscalable fabrication processes of the perovskite solar modules, which enables the champion efficiencies of 17.08% for 5 × 5 cm2 solar modules on an aperture area of 22.4 cm2. This novel design concept of hole-selective contacts provides a promising strategy for further improving the perovskite solar cell efficiency and stability.


Figure 3: (a) Schematic illustration for the scalable blade coating of large-area perovskite films. Cross-section SEM image of the fully blade-coated perovskite solar sub-module. I–V curve of the champion 15 cm × 15 cm perovskite solar sub-module. Inset: photograph of the sub-module with a series connection of 21 subcells. (b) J–V curves of the SA-BPP-based solar module on an aperture area of 22.4 cm2, the inset shows the module architecture with P1, P2, and P3 patterns. Photographs of the 5 x 5 cm2 solar module based on SA-BPP hole-selective contact.

3.4 Flexible perovskite solar cells.

Sisi He, Sibo Li, Anning Zhang, Guanshui Xie, Xin Wang, Jun Fang, Yabing Qi*, Longbin Qiu​*, "Residual strain reduction leads to efficiency and operational stability improvements in flexible perovskite solar cells" Mater. Adv. 3, 6313 (2022).

Flexible perovskite solar cells (F-PSCs) exhibit potential for portable power sources applications (such as wearable and portable electronics and lightweight power supply). We reported on a strategy to fabricate residual strain-free F-PSCs based on polyethylene naphthalate/indium tin oxide (PEN/ITO) by a pre-applied compressive strain on the flexible substrate. The crystal growth expansion and mismatched mechanical properties between the substrate and the perovskite layer induce the bulk residual strain deteriorating performance and stability. A specific pre-coating strategy on the flexible substrate has been devised to alleviate the gradient strain of the perovskite layer on the flexible substrate. By implementing a bottom SnO2 layer optimization and utilizing phenethylammonium iodide (PEAI) to passivate the strain-free perovskite layer, a remarkable efficiency of 18.71% has been achieved for the F-PSC. The residual strain free F-PSC showed a prolonged mechanical flexibility, which retained 80% of its initial performance after 1500 tension-only bending cycles.

3.5 Metal halide perovskite materials in light-emitting diodes.

Congyang Zhang, Silvia Mariotti, Luis K Ono, Chenfeng Ding, Kirill Mitrofanov, Caiyi Zhang, Shuai Yuan, Penghui Ji, Jiahao Zhang, Tianhao Wu, Ryota Kabe, Yabing Qi*, "A hole injection monolayer enables cost-effective perovskite light-emitting diodes" J. Mater. Chem. C​ 11, 2851-2862 (2023).

Perovskite materials possess desirable optoelectronic properties and are also promising candidates in the field of displays and light sources. In our recent study (Figure 4), we employed a [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) based hole injection monolayer (HIML) aiming cost-effective fabrication of efficient perovskite ligh-emitting diodes (PeLEDs). The ITO/2PACz-based devices reached a peak external quantum efficiency (EQE) of 11.6% at a current density of ~4.1 mA cm2. In comparison, the EQE of the bare ITO-based device is only 7.1%. In addition, an ITO/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)-based PeLED resulted in even lower electroluminescence (EL) performance with a peak EQE of 1.8%. Overall, the significant improvements of the device performance based on the 2PACz HIML clearly demonstrate the great potential for PeLEDs. 

Figure 4: Device structure of the hole injection monolayer (HIML)-based Perovskite LED (PeLED). The electroluminescence spectra of green, pure-blue, and sky-blue HIML-based PeLED. The inset photographs show the HIML-based PeLED under operation. The photograph of a large-area HIML-based PeLED with green emission and device area of ~60 mm2.

3.6 Progress on low-cost efficient energy storage devices.

Chenfeng Ding, Yuan Liu, Luis K Ono, Guoqing Tong, Congyang Zhang, Jiahao Zhang, Jinle Lan, Yunhua Yu, Bingbing Chen, Yabing Qi*, "Ion-regulating Hybrid Electrolyte Interface for Long-life and Low N/P Ratio Lithium Metal Batteries" Energy Storage Mater.​ 50, 417 (2022).

Taehoon Kim, Luis K. Ono, Yabing Qi*, "Understanding the nucleation and growth of the degenerated surface structure of the layered transition metal oxide cathodes for lithium-ion batteries by operando Raman spectroscopy" J. Electroanal. Chem.​​​ 915, 116340 (2022).

Taehoon Kim, Luis K. Ono, Yabing Qi, Yabing Qi*, "Understanding the active formation of a cathode–electrolyte interphase (CEI) layer with energy level band bending for lithium-ion batteries" J. Mater. Chem. A​ 11, 221-231 (2023).

Lithium (Li) metal anodes are widely regarded as a highly promising option for the development of next-generation high-energy density rechargeable batteries. This is largely due to their exceptional theoretical capacity, which stands at 3860 mA/g, a figure approximately ten times greater than that of graphite anodes. Additionally, their low density of 0.59 g/cm3 and low reduction potential of -3.04 V versus the standard hydrogen electrodes further enhance their appeal. However, the electro-chemo-mechanical instability of Li anodes during the repeated deposition/stripping processes limits their extensive practical application. In our of the studies (Figure 5a), we report a robust cellulose-based composite gel electrolyte (r-CCE) capable of tuning ion transport and stabilizing Li-ion deposition on Li metal anode. The r-CCE with excellent electrolyte wettability and mechanical/thermal durability is achieved via the construction of a unique nacre-like structure via calendering bacterial cellulose (BC) and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) particles. The utilization of r-CCE in the assembly of Li/LiNi8.15Co1.5Al0.35O2 (NCA) cells has resulted in a significant enhancement in capacity, rate, and cyclic stability, even when subjected to a lean electrolyte condition and a high areal density of cathode materials (25 mg/cm2). This study offers a fresh perspective on the creation of a diverse range of separators, which can be employed to construct safe and reliable Li metal batteries that outperform conventional Li metal batteries.

Lithium-ion batteries have garnered significant attention as a promising energy storage technology owing to their high energy density, high operating voltage, and low self-discharge property. Among the most preferred electrode materials for lithium-ion batteries are cathodes with Li-layered transition metal oxides, exemplified by LiNi1-x-yCoxMnyO2 (where x < 1 and y < 1). Despite the superior performance of these layered cathode materials, a significant challenge persists for their large-scale implementation. Capacity fading is a common issue experienced by both materials during charge and discharge processes. To examine the degradation process that occurs during electrochemical cycling, an operando cell was designed in the current investigation. The operando Raman study provided insights into this process, as shown in Figure 5b. Herein, for the first time to our knowledge, we reveal the nucleation-merging mechanism by the degenerated layers on the cathode surface, which is connected to the severe capacity fading and voltage decay of the lithium-ion batteries. The insights gained from this investigation have important implications for the design of battery cathodes that can support long-term, stable operation under varying conditions.

Figure 5: (a) Schematic illustration of the fabrication of the multifunctional robust cellulose-based composite gel electrolyte (r-CCE) matrix. (b) The surface degradation mechanism of the layered LiNi1/3Co1/3Mn1/3O2 cathode examined on charge–discharge using an operando Raman cell.

3.7 Review articles

Hui Zhang, Yabing Qi*, "Investigating lithium metal anodes with nonaqueous electrolytes for safe and high-performance batteries" Sustainable Energy Fuels​ 6, 954–970 (2022).

Yan Jiang, Sisi He, Longbin Qiu, Yixin Zhao, Yabing Qi​*, "Perovskite solar cells by vapor deposition based and assisted methods" Applied Physics Reviews​​​​ 9, 021305 (2022).

Hang Li, Mingzhen Liu, Meicheng Li, Hyesung Park, Nripan Mathews, Yabing Qi, Xiaodan Zhang, Henk J Bolink, Karl Leo, Michael Graetzel, Chenyi Yi*, "Applications of vacuum vapor deposition for perovskite solar cells: A progress review"  iEnergy​  1, 434-452 (2022).

Zhichun Yang, Zonghao Liu*, Vahid Ahmadi, Wei Chen, Yabing Qi*, "Recent Progress on Metal Halide Perovskite Solar Minimodules"  Solar RRL​  6, 2100458 (2022).

4. Publications

4.1 Journals

    →Please see our publications page for published journals

4.2 Books and Other One-Time Publications


4.3 Oral and Poster Presentations 

1. Yabing Qi, “Research on metal halide perovskite materials and their solar cell applications from a surface science perspective”, KPS 70th Anniversary and 2022 Fall Meeting, Busan, Korea (October 19-21, 2022) (Invited talk).

2.  Yabing Qi, “Surface Science Studies on Metal Halide Perovskite Materials and Their Solar Cell Applications”, International Workshop on Organic and Perovskite Electronics, Hong Kong, China (September 19-21, 2022) (Keynote talk).

3.  Tianhao Wu,  “Elimination of Light-Induced Degradation at the Nickel Oxide-Perovskite Heterojunction towards Long-Term Operationally Stable Inverted Perovskite Solar Cells”, Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP23), Kobe, Japan (Jan 22-25, 2023) (oral presentation).


5. Intellectual Property Rights and Other Specific Achievements

  • Provisional patent application (Year of application: 2023)
  • Prof. Yabing Qi received Kao Science Award.
  • Prof. Yabing Qi was listed as one of the Clarivate Highly Cited Researchers.
  • Dr. Luis K. Ono was listed as one of the Clarivate Highly Cited Researchers.

6. Meetings and Events