Chemical Trend of Nonradiative Recombination in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>Cu</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>In</mml:mi><mml:mo>,</mml:mo><mml:mi>Ga</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:msub><mml:mi>Se</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> Alloys
Baoying Dou, Stefano Falletta, Jörg Neugebauer, Christoph Freysoldt, Xie Zhang, Su‐Huai Wei
Abstract
Understanding nonradiative recombination is important for improving semiconductor devices. For Cu(In,Ga)Se${}_{2}$ (CIGS) solar cells, antisite defects have long been considered the main recombination centers, yet the underlying mechanism has remained elusive. Here first-principles calculations show that these ``killer centers'' themselves cannot capture holes efficiently for effective recombination. However, internal conversion to the distorted neutral DX center does open an efficient hole-capture pathway, and DX's stability in CIGS increases with Ga concentration, which resolves the longstanding issue of why the efficiency of CIGS solar cells decreases at high Ga concentration.