Regensburg 2022 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 34: Focus Session: Perspectives in Cu(In,Ga)Se 2

HL 34.4: Vortrag

Donnerstag, 8. September 2022, 16:15–16:30, H33

Identification of nonradiative recombination centers in CuInSe2 and CuGaSe2 — •Baoying Dou¹, Stefano Falletta², Christoph Freysoldt¹, and Jörg Neugebauer¹ — ¹Max-Planck-Institut für Eisenforschung GmbH — ²Ecole Polytechnique Fédérale de Lausanne

Cu(In,Ga)Se2 is a promising solar absorber for thin-film solar cell applications. Nonradiative carrier recombination is one of the key processes that limits the device efficiency. To achieve high performance, it is crucial to identify the critical defects and quantify their induced nonradiative recombination rates. Prior first-principle calculations proposed that the antisites InCu and GaCu, are donors with a transition levels in the band gap, so they may act as nonradiative recombination centers. However, the existence of transition levels in the band gap does not necessarily trigger nonradiative recombination. Using first-principles methods, we quantitatively show that internal conversion in the neutral charge state to the distorted DX center configuration plays a crucial role in carrier recombination by opening an efficient hole capture pathway. The positive charge state returns to the anti-site configuration without barrier to complete the entire recombination cycle. However, our calculations show that the DX center is only stable in CuGaSe2, not in CuInSe2. We discuss the consequences of these findings for defect engineering in CuInSe2, CuGaSe2, and its alloys.