Department of Materials Science and Engineering, Kookmin Univ.
[Hole/electron] We analyzed thermoelectric properties by fine-tuning the doping level through organic electrochemical doping. We investigated the local density of states (DOS) in four different polymers based on Poly[(2,5-bis(2-alkyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophene-2-yl)benzo[c][1,2,5]thiadiazole)], which have different side chains. By doing so, we uncovered the disorder effect on the thermoelectric properties of semicrystalline polymers.[1] Using a new donor-donor (D-D') type polymer (PIDTSCDTS), we compared the thermoelectric properties of this polymer using three doping methods: sequential doping (SqD), solution-mixed doping (MxD), and hybrid doping (HyD). We found that the hybrid doping method achieved the highest electrical conductivity of approximately 500 S cm⁻¹, originating from degenerative doping in the crystalline and amorphous regions. Our research suggests a direction towards further optimizing TE properties by carefully considering degenerate doping and band-like carrier transport, with a focus on maximizing during the molecular design and doping process.[2] | |
[Ion] We have recently developed an ionic thermoelectric device that operates even in low -humidity environments. Traditional hydrogels are highly sensitive to humidity, making them difficult to use as thermoelectric devices in low-humidity conditions. However, in this study, we utilized long ionic side chains and bulky ions, allowing ion transport along the chains, which reduced the influence of water absorption. With five p-n couples of p-type and n-type polymers, the device generated an impressive output voltage of 0.8 V at 30% RH, with a 20°C temperature difference.[3] |
DSSC
We fabricated a PtNF web through electrospinning and used it as a counter electrode in DSSCs, replacing indium-doped tin oxide (ITO) or fluorine-doped tin oxide (FTO) glass. This approach is cost-effective and easy to produce. The photovoltaic performance increased, achieving a power conversion efficiency of 6.0%, which is up to 83% of that in a conventional DSSC using Pt-coated FTO glass as the counter electrode. The newly designed DSSCs containing PtNF webs exhibit highly stable photoelectric conversion efficiency, excellent catalytic, conductive, and transparent properties, as well as long-term stability.[4] |
Relevant Publication
1 |
Choi, W.; Kim, S.; Lee, S.; Jung, C.; Tripathi, A.; Lee, Y.; Han, Y.* Lee, H.*, Unravelling Disorder Effects on Thermoelectric Properties of Semicrystalline Polymers in a Wide Range of Doping Levels. Small Methods 2023, 7(2), 2201145. |
2 | Tripathi, A.; Lee, Y.; Jung, C.; Kim, S.; Lee, S.; Choi, W.; Park, C.; Kwon, Y.; Lee, H.* & Woo, H.* ,A heavily doped D-D'-type polymer with metal-like carrier transport via hybrid doping. Journal of Materials Chemistry C 2023, 11(17), 5646-5656. |
3 |
Kim, S.; Ham, M.; Lee, J.; Kim, J.; Lee, H.*, & Park, T.*, Side‐Chain Engineered P Or N‐Type Nonaqueous Polymeric Ionic Gels for Sustainable Ionic Thermoelectrics. Advanced Functional Materials 2023, 33(52), 2305499. |
4 | Kim, J.; Kang, J.; Jeong, U.; Kim, H.; Lee, H.*, Catalytic, Conductive, and Transparent Platinum Nanofiber Webs for FTO-Free Dye-Sensitized Solar Cells. ACS Applied Materials & Interfaces 2013, 5(8), 3176-3181. |
5 | Arivunithi, V. M.; Kim, S.; Choi, J.; Sung, J.; Yoo, H.; Shin, E.; Noh, Y.; Gal, Y.; Lee, H.*; Jin, S.*, Enhanced efficiency and reduced hysteresis by TiO2 modification in high-performance perovskite solar cells. Organic Electronics 2020, 86, 105922. |
6 |
Lee, W.*; Kim, S.; Kang, J.; Han, K.; Lee, H.*, Inverse opal photoelectrode of Nb-doped TiO2 nanoparticles for dye-sensitized solar cell. Polymer Bulletin 2016, 73(9), 2547-2555.
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