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Activated Electron‐Transport Layers for Infrared Quantum Dot Optoelectronics
Author(s) -
Choi Jongmin,
Jo Jea Woong,
Arquer F. Pelayo García,
Zhao YongBiao,
Sun Bin,
Kim Junghwan,
Choi MinJae,
Baek SeWoong,
Proppe Andrew H.,
Seifitokaldani Ali,
Nam DaeHyun,
Li Peicheng,
Ouellette Olivier,
Kim Younghoon,
Voznyy Oleksandr,
Hoogland Sjoerd,
Kelley Shana O.,
Lu ZhengHong,
Sargent Edward H.
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201801720
Subject(s) - materials science , optoelectronics , photovoltaics , passivation , quantum dot , doping , band gap , electrode , solar cell , tandem , energy conversion efficiency , ultraviolet , quantum efficiency , nanotechnology , photovoltaic system , layer (electronics) , biology , ecology , chemistry , composite material
Photovoltaic (PV) materials such as perovskites and silicon are generally unabsorptive at wavelengths longer than 1100 nm, leaving a significant portion of the IR solar spectrum unharvested. Small‐bandgap colloidal quantum dots (CQDs) are a promising platform to offer tandem complementary IR PV solutions. Today, the best performing CQD PVs use zinc oxide (ZnO) as an electron‐transport layer. However, these electrodes require ultraviolet (UV)‐light activation to overcome the low carrier density of ZnO, precluding the realization of CQD tandem photovoltaics. Here, a new sol–gel UV‐free electrode based on Al/Cl hybrid doping of ZnO (CAZO) is developed. Al heterovalent doping provides a strong n‐type character while Cl surface passivation leads to a more favorable band alignment for electron extraction. CAZO CQD IR solar cell devices exhibit, at wavelengths beyond the Si bandgap, an external quantum efficiency of 73%, leading to an additional 0.92% IR power conversion efficiency without UV activation. Conventional ZnO devices, on the other hand, add fewer than 0.01 power points at these operating conditions.