Alternative Energy: DSSC(Dye-Sensitized Solar Cell)

     Hello ladies and gentleman, this is the ambassador of South Korea. Today, I would like to discuss the alternative energy that you guys would be not fully aware of. This is a type of solar energy, and its name is DSSC (Dye-Sensitized Solar Cell).

   In fact, for the last two months, I have been writing a mini report about DSSC and while writing I learned a lot about DSSC both in environmentally, scientifically and so on. DSSC is now being developed but it is not commercialized yet. So why should we develop DSSC? Why do people say that DSSC is spotlighted for the next generation alternative energy? Compared to solar energy, which uses solar as well, DSSC is much cheaper and maintains longer. Moreover, it is more environmentally friendly and requires less amount of sunlight.

   In order to understand DSSC, we need to know some scientific backgrounds in advance. First is the 'energy band gap'. 

Electron energy is consisted of conduction band and valence band, and between them, the band gap exists. We call that Fermi level and the size of band gap decides the feature of every material. When conduction band and valence band is overlapped, it is what we call metal, and when the band is too big, it is insulator. And finally, when the band gap is not that big that free electrons can exist, it is semi-conductor. DSSC is a type of semi-conductor and the band diagram of solar cell can be expressed as below.

   DSSC is a type of diode so I would like to briefly explain diode as well. The picture below is the ideal I-V graph of diode. PN diode is consisted of N semi-conductor (anode:+) and P semi-conductor (cathode:-). Current can flow only when the current flows from anode to cathode, which is forward current.

     Now, let's discuss the structure of DSSC. You can refer to the picture below for your better understanding. DSSC can be divided into 4 parts photo anode, sensitizer, electrolyte, and counter electrode. The glass that we use is conductive glass that is helps the current flow. I actually made DSSC, which was very inspiring.

    So, I would like to share how we made DSSC. First, is making the photo anode. There are various ways that we can use to spread titania paste, but we used is screen printing method. Then, for about 5 hours, the process of dying should be done. After five hours, we should clean it with ethanol.

screen printing machine

photo anode

The procedure of making counter electrode is easier than photo anode. We should paste platinum on another conductive glass. Then, for the effective dying, we should put melting sheet and add heat.

counter electrode

To reduce the resistance, we spread gallium on both the photo anode and counter electrode. Lastly, when we drop electrolyte and put those two conductive glasses together with clips, the test DSSC is completed! For the commercial ones that needs more precise making to reduce the evaporation of electrolyte, we should seal it better.

test DSSC

To test the efficiency of DSSC, we can connect DSSC with artificial light source and a source meter. We used KEITHLEY 2400 and drew the I-V curve. By making these DSSC, we conducted a few experiment concerned with the temperature of the DSSC.

DSSC connected with artificial light source

   It was a very meaningful activity for me since I could actually make DSSC myself. I could understand DSSC better than just learning by words. It made me to think more on the importance of alternative energy. DSSC has still some problems and things to be solved to be commerialized but I hope DSSC to be used world wide someday cause it possess some advantages that solar power does not have. I always feel happy when the world is moving forward to develop new energies that can ehance our life and help make a cleaner earth. Thanks :)