Title :
Analysis and design of core-shell upconverting nanostructures
Author :
Wistey, Mark A. ; Patel, Vaibhav ; Loof, Joseph L. ; O´Brien, William A. ; Meng Qi ; Erdman, Anthony J. ; Stephenson, Chad A.
Author_Institution :
Univ. of Notre Dame, Notre Dame, IN, USA
Abstract :
Core-shell upconverting nanostructures (CSUNs) improve upconversion efficiency by blocking midgap recombination. Consecutive 3-level systems absorb strongly but preserve long carrier lifetime in their final states. Germanium has a nearly-direct bandgap ideal for a CSUN core: strong optical absorption yet slow recombination. Electrons in the indirect conduction band valley absorb a second photon to escape the shell and reach the host, unable to return. Our model indicates that free carrier absorption (FCA) from L to continuum is the limiting step. Surface plasmon resonances (SPR) in Ge-AlGaAs may selectively enhance this absorption. CSUNs would help preserve current matching at dawn and dusk.
Keywords :
aluminium compounds; carrier lifetime; electrons; gallium arsenide; germanium; light absorption; nanostructured materials; solar cells; surface plasmon resonance; 3-level systems; CSUN core; FCA; Ge-AlGaAs; SPR; carrier lifetime; core-shell upconverting nanostructures; electrons; free carrier absorption; indirect conduction band valley; optical absorption; surface plasmon resonances; upconversion efficiency improvement; Absorption; Materials; Photonic band gap; Plasmons; Scattering; Spontaneous emission;
Conference_Titel :
Photovoltaic Specialist Conference (PVSC), 2014 IEEE 40th
Conference_Location :
Denver, CO
DOI :
10.1109/PVSC.2014.6925628
