Development of a-Si solar cells using “liquid–Si printing”

Abstract

Film properties of hydrogenated amorphous silicon (a-Si:H) fabricated by “liquid–Si printing” (LSP) were investigated in detail and compared to the conventional plasma enhanced chemical deposition (plasma–CVD) method. LSP a-Si:H films (LSP films) had lower film density and larger size void than the a-Si:H films deposited by plasma–CVD (CVD films). On the other hand, the LSP films had high photoconductivity comparable to device grade a-Si:H films and higher photostability than the CVD films. Thus, the LSP films were drastically different from conventional CVD films. The conversion efficiency of the bifacial solar cells (glass/TCO/n(LSP film)/i(LSP film)/p(CVD film)/TCO/electrode), which was a problem because of the missing link between high photoconductivity and low cell performance, were improved. Undoped CVD film was inserted between the i- and p-layers to suppress the plasma damage to the active layer printed by LSP when depositing a B doped a-Si:H by plasma–CVD. As a result, we achieved conversion efficiencies of 1.1% with n side incidence and 3.1% with p side incidence.