Local electrical transport measurements with scanning probe microscopy on polycrystalline (PX) p-CuInSe2 and p-Cu(In,Ga)Se2 films show that the photovoltaic and dark currents for bias voltages smaller than 1 V flow mainly through grain boundaries (GBs), indicating inversion at the GBs. Photocurrent for higher bias flows mainly via the grains. Based on these results and our finding of ∼100 meV GB band bending we deduce the potential landscape around the GBs. We suggest that high grain material quality, leading to large carrier mobilities, and electron-hole separation at the GBs, by chemical and electrical potential gradients, result in the high performance of these PX solar cells.
- Conductive AFM
- Grain boundaries
- Solar cell
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films