Katherine Song, 2011, Electrical Engineering
The objective of my internship project was to characterize two types of non-traditionally structured solar cells – namely, organic bulk heterojunction cells and silicon nanowire cells. The organic solar cells, which were comprised of either a P3HT/PCBM blend or a PCDTBT/PC70BM blend, were fabricated at University of California – Santa Barbara. For these organic solar cells, which are attractive because of their low cost, low weight, and flexibility, a model was developed and experimentally tested to extract internal diode characteristics from experimentally measured photocurrent, which is affected by series resistance originating from various sources in the cell. In addition, the photoconductivity spectrum was measured to provide an estimate for the band offset of the heterojunction blend making up the cell. For the silicon nanowire solar cells, which were fabricated at PARC, photocurrent as a function of voltage and the photoconductivity spectrum were measured to determine whether the added morphology from the grown nanowires enhanced the performance of otherwise “conventional” amorphous silicon p-i-n solar cells.