Surface and bulk effects of K in highly efficient Cu1-xKxInSe2 solar cells

Christopher P. Muzzillo, Jian V. Li, Lorelle M. Mansfield, Kannan Ramanathan, Timothy J. Anderson

研究成果: Article同行評審

7 引文 斯高帕斯(Scopus)

摘要

To advance knowledge of the beneficial effects of K in Cu(In,Ga)(Se,S)2 (CIGS) photovoltaic (PV) absorbers, recent Cu-K-In-Se phase growth studies have been extended to PV performance. First, the effect of distributing K throughout bulk Cu1-xKxInSe2 absorbers at low K/(K+Cu) compositions (0 ≤ x ≤ 0.30) was studied. Efficiency, open-circuit voltage (VOC), and fill factor (FF) were greatly enhanced for x ~ 0.07, resulting in an officially-measured 15.0%-efficient solar cell, matching the world record CuInSe2 efficiency. The improvements were a result of reduced interface and bulk recombination, relative to CuInSe2 (x ~ 0). However, higher x compositions had reduced efficiency, short-circuit current density (JSC), and FF due to greatly increased interface recombination, relative to the x ~ 0 baseline. Next, the effect of confining K at the absorber/buffer interface at high K/(K+Cu) compositions (0.30 ≤ x ≤ 0.92) was researched. Previous work showed that these surface layer growth conditions produced CuInSe2 with a large phase fraction of KInSe2. After optimization (75 nm surface layer with x ~ 0.41), these KInSe2 surface samples exhibited increased efficiency (officially 14.9%), VOC, and FF as a result of decreased interface recombination. The KInSe2 surfaces had features similar to previous reports for KF post-deposition treatments (PDTs) used in world record CIGS solar cells—taken as indirect evidence that KInSe2 can form during these PDTs. Both the bulk and surface growth processes greatly reduced interface recombination. However, the KInSe2 surface had higher K levels near the surface, greater lifetimes, and increased inversion near the buffer interface, relative to the champion bulk Cu1-xKxInSe2 absorber. These characteristics demonstrate that K may benefit PV performance by different mechanisms at the surface and in the absorber bulk.

原文English
頁(從 - 到)45-53
頁數9
期刊Solar Energy Materials and Solar Cells
185
DOIs
出版狀態Published - 2018 十月

All Science Journal Classification (ASJC) codes

  • 電子、光磁材料
  • 可再生能源、永續發展與環境
  • 表面、塗料和薄膜

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