High-efficiency Cu(In,Ga)Se thin-film solar cells with a novel In(OH):Zn buffer layer

Light soaking effect on photocurrent collection in (Zn,Mg)O/Cu(In,Ga)Se2 solar cells

“…This is the phenomenon that the efficiency of CIGS solar cells is improved after exposure to white light for typically 30 min, generally due to increases in fill factor (FF) and open-circuit voltage (V oc ). The different degrees of the LS effect were reported in CIGS solar cells with various buffer/window layer materials [2][3][4]. In our previous report, we fabricated the CIGS solar cells with controlled conduction band offset (CBO) between window/CIGS layers by a (Zn,Mg)O (ZMO) window layer, and we revealed that the degree of the LS effect was controlled by the CBO [5].…”

“…The energy conversion efficiency of CIGS solar cells is approaching to 20% [1]; however the understanding of structural and electronic properties of CIGS solar cells is still low. One of the unclear mechanisms regarding the electronic properties of CIGS solar cells is the light soaking (LS) effect [2][3][4]. This is the phenomenon that the efficiency of CIGS solar cells is improved after exposure to white light for typically 30 min, generally due to increases in fill factor (FF) and open-circuit voltage (V oc ).…”

Photo current metastability in Cu(In,Ga)Se2 solar cells with controlled conduction band alignment

“…A metastability of current density-voltage (J-V) characteristics, so called a light soaking (LS) effect [1] was observed in a Cu(In,Ga)Se 2 solar cell. The LS effect which increases the cell efficiency due to the increase in fill factor (FF) and open-circuit voltage (V oc ) is triggered by an exposure to white light.…”

Metastability of Zn1−xMgxO/Cu(In,Ga)Se2 solar cells with different conduction band offset values

“…Models for the generation mechanism of the LS effect such as the migration of copper atoms [4] and the persistent photoconductivity of the CIGS layer [5] were proposed; however, the mechanism has not been clarified fully. The key factor for the LS effect would be the buffer (window)/CIGS heterointerface, especially conduction band offset (CBO) judging from the report that the LS effect is affected by the buffer layer [6]. To investigate the effect of the CBO, it is necessary to control the electron affinity of window or CIGS layers.…”