Solar Cells. Jong Hak Kim Chemical & Biomolecular Engineering Yonsei University

Transcription

1 Solar ells Jong Hak Kim hemical & Biomolecular Engineering Yonsei University

2 omparison of Solar ells 반도체태양전지장점 고효율 (30% 이상 ) 태양전지제조가능 단점 고효율태양전지제조시원료비용및제조비용부담이매우큼고순도를요하는공정이므로제조공정이복잡하고어려움환경에유해한물질발생 광감응염료태양전지장점 기존비정질실리콘태양전지에버금가는에너지변환효율 ( 습식태양전지 ) 제조단가는실리콘태양전지의 5분의 1 수준환경친화적제조공정 단점 습식태양전지의경우, 용매의휘발및누출에따른내구성저하문제

3 rganic Solar ells rganic Solar ells - heap, efficient - Improved stability - Transparent, flexible, colorful

4 Principles of Solar ells Dye-Sensitized Solar ells (DSS)

5 Principles of Solar ells Dye-sensitized solar cells e - ~ Ru Dye (sensitizer)/ti 2 H hn I 3 - Ti 2 Ru NS NS IT : dye I - IT or Pt : semiconductor H S S + + e - Redox couple : 3I - I e - : electrolyte

6 Structure of Solar ells e Pt-coated glass I - /I 2 electrolyte Dye/Ti 2 layer (10 15 μm) Nanocrystalline semiconductor Sn 2 -based T Film surface H N N N Ru N NS NS H

7 Principles of Solar ells Dye-sensitized solar cells (DSS) ~ e - S S + e - I 3 - I - e - S S * S * e - (Ti 2 ) cb + S + 2S + + 3I - 2S + I - 3 I e - 3I -

8 haracteristics of DSS - promising candidates for renewable clean energy source Low osts : 1/3 ~1/5 of conventional Si S/ Green Technology: non-toxic mater. Transparent: Power window, smart window oloration: Rainbow cell Flexibility: Flexible Battery & Device TYTA-AISIN 精機 Ti 2 paste Heating Dye adsorption electrolyte SAIT

9 Trends in Industry DSS Manufacturers INAP, Gelsenkirchen, Grmany EN, Petten, Netherlands Solaronix, Aubonne, Swiss IMRA-Europe, France Konarka, MA 현대자동차, 삼성 SDI, 동진세미켐, 이건창호등 Japan 50 companies STI, AU

10 Key omponents 1. Nanocrystalline Semiconductor - surface area, porosity, pore size distribution, light scattering, electron percolation, Anatase (Ti 2 ), Zn, Sn 2, Nb Sensitizers (Dye) - Distribution on semiconductor surface, spectral properties, redox properties in ground and excited states anchoring groups (carboxylate or phosphonate) 3. Electrolyte - ionic conductivity, electron barrier and hole conductor, redox potential, mechanical separator, interfacial contact for dye, Ti 2 and counter electrode (I - /I 3 ) 4. Transparent conductive oxide (conductivity, transmittance), sealing, metal grid, counter electrode

11 Semiconductor layer Basic Requirements - Proper energy level of conduction band for electron injection from excited dyes - Wide band gap for no absorption of visible light - Large surface area for large amount of dye adsorption - High porosity for deeper penetration of electrolyte solution - High electron conductivity for high current density and voltage - Slow recombination for high current density and voltage

12 Semiconductor layer Ti 2 : E cb (- 3.9 V), E g (3.2 V) - high efficiency: ~10.5 % at AM 1.5 (100 mw/cm 2 ) - high electron conductivity - good connectivity and necessary porosity crystal formation with small defects - good adhesion to electrode - slow recombination (related with surface state or defects)

13 Dyes Basic Requirements 1. Light absorption from whole visible light (400 ~ 900 nm) 2. High IPE (incident photon-to-current conversion efficiency). 3. Good interaction with semiconductor surfaces such as Ti2. 4. Good interaction with electrolytes 5. Long-term chemical stability 6. Low cost

14 Dyes IPE (incident photon-to-current conversion efficiency)

15 Electrolytes Redox couples: I - /I 3-, Br - /Br 3-, u, phthalocyanine, SN, ferrocyanine, dissolved in a solvent. - Energy level lower than that of the counter electrode but higher than that of dye HM. - Fast ionic conduction - Fast redox reactions - Small charge transfer resistance at the interfaces - Slow recombination of electrons in the Ti2 layer.

16 Roles of Electrolytes Electrolytes: I - and I 3- conductor interfacial contactor for dye electron barrier or hole conductor electrochemical reaction media mechanical separator ontact of electrolyte with dyes: H N N NS I - Ti Ru 3 2 N NS N e - H e - I -

17 Recent Research Trends Higher Efficiency & Stability

18 urrent Issues 1. Understanding electron dynamics in DSSs 2. Electrolyte evaporation and degradation Quasi or solid state DSSs 3. New sensitizers (dye or quantum dot) 4. Recombination in the oxide layer Preparation of the second oxide layer for passivation 5. Flexible DSSs 6. Increasing efficiency and performance 7. Long-term performance