| Autor: |
Xin H; Department of Chemical Engineering, University of Washington, Seattle, WA, USA. h2@uw.edu., Vorpahl SM, Collord AD, Braly IL, Uhl AR, Krueger BW, Ginger DS, Hillhouse HW |
| Jazyk: |
angličtina |
| Zdroj: |
Physical chemistry chemical physics : PCCP [Phys Chem Chem Phys] 2015 Oct 07; Vol. 17 (37), pp. 23859-66. Date of Electronic Publication: 2015 Aug 25. |
| DOI: |
10.1039/c5cp04707b |
| Abstrakt: |
Passive grain boundaries (GBs) are essential for polycrystalline solar cells to reach high efficiency. However, the GBs in Cu2ZnSn(S,Se)4 have less favorable defect chemistry compared to CuInGaSe2. Here, using scanning probe microscopy we show that lithium doping of Cu2ZnSn(S,Se)4 changes the polarity of the electric field at the GB such that minority carrier electrons are repelled from the GB. Solar cells with lithium-doping show improved performance and yield a new efficiency record of 11.8% for hydrazine-free solution-processed Cu2ZnSn(S,Se)4. We propose that lithium competes for copper vacancies (forming benign isoelectronic LiCu defects) decreasing the concentration of ZnCu donors and competes for zinc vacancies (forming a LiZn acceptor that is likely shallower than CuZn). Both phenomena may explain the order of magnitude increase in conductivity. Further, the effects of lithium doping reported here establish that extrinsic species are able to alter the nanoscale electric fields near the GBs in Cu2ZnSn(S,Se)4. This will be essential for this low-cost Earth abundant element semiconductor to achieve efficiencies that compete with CuInGaSe2 and CdTe. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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