Experimental determination of the photon economy in polycrystalline thin film photovoltaic materials and devices

✍ Scribed by J.A. Bragagnolo; E.A. Fagen

• Publisher: Elsevier Science
• Year: 1980
• Weight: 510 KB
• Volume: 1
• Category: Article
• ISSN: 0379-6787
• DOI: 10.1016/0379-6787(80)90077-0

✦ Synopsis

The optical measurement and analysis of polycrystalline thin film solar cell materials and devices is complicated by diffuse scattering at all interfaces due to roughness and diffuse volume scattering due to grain boundaries and orientation effects. An experimental approach using directional spectral reflectance and absorptance measurements with 4~ collection geometry is described which provides an expedient route to the determination of device photon losses, intrinsic optical properties of polycrystalline materials and the effects of layer morphology on the photon economy of solar cells. This technique is applied to the photon loss analysis of thin film CdS/Cu2S cells and the assessment of Zn3P2 as a photovoltaic material. It is concluded that cell morphology is a key contributor to the high photon efficiency of polycrystalline CdS/Cu2S cells. Also, the discrepancy between bulk and thin film absorption edge data for Zn3P2 is reduced and the intrinsic absorption edge of evaporated films is revealed to be exponential. Other applications of this technique are discussed.