Investigation Of Carrier Collection From Qd Tjscs

Quantum dot triple junction solar cells (QD TJSCs) have potential for higher efficiency for space and terrestrial applications. Extended absorption in the QD layers can increase efficiency by increasing the short circuit current density of the device, as long as carrier extraction remains efficient and quality of the bulk material remains high. Experimental studies have been conducted to quantify the carrier extraction probability from quantum confined levels and bulk material. One studies present insight to the carrier extraction mechanisms from the quantum confined states through the use of temperature dependent measurements. A second study analyses the loss in carrier collection probability in the bulk material by investigating the change in minority carrier lifetimes and surface recombination velocity throughout the device. Recent studies for space applications have shown response from quantum structures to have increased radiation tolerance. The role strain and bonding strength within the quantum structures play in improving the radiation tolerance is investigated. The combination of sufficiently good bulk material and device enhancement from the quantum confinement leads to temperature dependent measurements that show TJSCs outperform baseline TJSCs near and above 60 degrees C. Insight into the physical mechanisms behind this phenomenon is presented.