ZnPc-tetracene combo achieves EQE leap in silicon solar cells

Researchers have demonstrated that crystalline silicon solar cell efficiency can be enhanced using singlet exciton fission with tetracene and zinc phthalocyanine (ZnPc) layers. The modified silicon microwire solar cells achieved 138% external quantum efficiency for photons absorbed in tetracene. ZnPc has been shown to dissociate triplet excitons in tetracene and enable sequential charge transfer to silicon, avoiding the inefficient Dexter mechanism. A 1 nm aluminum oxide (AlOx) layer was used to passivate the silicon surface while permitting charge tunneling. Performance was significantly improved with n⁺-doped silicon, while p⁺-doped cells were less effective. The microwire cells had shallow junctions and minimal shading to support carrier collection. According to the research team, control experiments confirmed that both ZnPc and AlOx layers were essential for effective interfacial coupling and performance gain.