Bifacial silicon heterojunction solar cells using transparent-conductive-oxide- and dopant-free electron-selective contacts

The development of transparent electron-selective contacts for dopant-free carrier-selective crystalline silicon (c-Si) heterojunction (SHJ) solar cells plays an important role in achieving high short-circuit current density (JSC) and consequently high photoelectric conversion efficiencies (PCEs). This becomes even more important when focusing on the development of bifacial solar cells. In this study, bifacial SHJ solar cells using a transparent-conductive-oxide-free and dopant-free electron-selective passivating contacts are developed, showing a JSC bifaciality of up to 97%. Intrinsic ZnOX layer deposited by atomic layer deposition was used in this structure, which simultaneously provides negligible passivation loss after annealing and enables a low contact resistivity on the electron-selective contact. With both side finger metal electrodes contact, this bifacial solar cell shows an efficiency of 21.2% under front-side irradiation and 20.4% under rear-side irradiation, resulting in an estimated output power density of 24.1 mW/cm2 when considering rear-side irradiance of 0.15 sun. Bifacial SHJ solar cells using a transparent-conductive-oxide-free and intrinsic ZnOX-based electron-selective passivating contacts are developed, showing a JSC bifaciality up to 97%. With both side finger metal electrodes contact, this bifacial solar cell shows an efficiency of 21.2% under front-side irradiation and 20.4% under rear-side irradiation, resulting in an estimated output power density of 24.1 mW/cm2 when considering rear-side irradiance of 0.15 sun. image