Influence of extended defects on the optoelectronic properties and control strategies in CdTe solar cells

The efficiency of CdTe polycrystalline thin-film solar cells remains substantially below the theoretical limit, with extended defects—particularly grain boundaries and dislocations—identified as critical performance-limiting factors. Conventionally regarded as deleterious recombination centers, grain boundaries have been shown to undergo n-type inversion via Cl segregation during CdCl2 treatment, forming localized p-n-p junctions that convert them into carrier-collecting channels, thereby emerging as a fundamental mechanism for performance enhancement. Concurrently, dislocations exhibit dual functionalities: their density can be suppressed through hole injection, while specific dislocation configurations demonstrate the capability to promote photogenerated carrier separation, challenging conventional defect paradigms. This review systematically analyzes the atomic configurations and electronic properties of extended defects in CdTe, elucidates their roles in optoelectronic processes, and evaluates corresponding passivation and engineering strategies. Prospective research directions including impurity-defect synergism and defect evolution stability are discussed, providing strategic insights for advancing CdTe photovoltaics through defect engineering.