Dresden 2009 – wissenschaftliches Programm
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SYOP: Symposium Organic Photovoltaics: From Single Molecules to Devices
SYOP 4: Organic Photovoltaics: from Single Molecules to Devices
SYOP 4.72: Poster
Donnerstag, 26. März 2009, 16:30–19:00, P1A
Organic ambipolar field effect transistor as model system for light absorption in organic solar cells — •Steve Pittner and Veit Wagner — Jacobs University Bremen, Germany
Since years the interest in organic solar cells is steadily growing. The main reasons are low production costs, suitability for processing on flexible substrates and their potential to provide renewable, environmental friendly energy. Yet their efficiency is still too low and their environmental stability is not sufficient for widespread applications.
In this contribution blends of P3HT and [60]PCBM are investigated by light absorption and photocurrent spectroscopy in transistor geometry, which allow to vary charge density and carrier type systematically by varying the gate potential. In this way relevant electro-optical properties for organic blend solar cell with stacked layer geometry is investigated by using ambipolar thin film transistor (TFT) with Au contacts and a blend made of P3HT and [60]PCBM. Furthermore it is shown, that stability in air ambient can be obtained by 30 nm Al2O3 encapsulation, which is assumed to mainly protect the air-sensitive PCBM.
The contributions of both organic semiconductors to the photocurrent spectra can be identified via their absorption spectra in the range 1.2 eV to 3.7 eV and is monitored for the different operation regimes. The data are interpreted in comparison with results of electrical measurements yielding the mobility for both carrier types and the trap distribution from hysteresis analysis.