[22p-P08-1~16] 13.9 Compound solar cells

▲ [22p-P08-2] Quantifying the influence of band tail recombination and quasi-fermi level splitting on the open-circuit voltage loss in CIGS solar cells

〇(D)Hamidou Tangara¹, Yulu He¹, Guo Junjie¹, Muhammad Monirul Islam¹, Shogo Ishizuka², Takeaki Sakurai¹ (1.Univ.Tsukuba, 2.AIST)

Keywords:CIGS solar cells, Quasi-fermi level splitting, Open-circuit voltage loss

In principle, the theoretical maximum photovoltaic efficiency and the loss mechanisms of any solar cell technology can be evaluated using the detailed balance limit formalism. The formalism assumes that (i) radiative recombination is the sole recombination channel in the cell and that (ii) the material exhibit a step-function-like absorptance with perfect absorption above the bandgap and zero absorption otherwise. However, practical solar cell materials display absorption with an exponential dependence below the bandgap known as the Urbach tail, which, in addition to the quasi-fermi level splitting (QFLS), has a huge impact on the loss mechanisms in the material. Here, we analyze the impact of both the Urbach tails and the QFLS on the V_OC loss mechanism in CIGS solar cell devices using full-spectrum fitting of the photoluminescence (PL) emission.