Efficient near ultraviolet to near infrared downconversion photoluminescence of La2GeO5: Bi3+, Nd3+ phosphor for silicon-based solar cells

Recently, downconversion materials have attracted considerable research due to large promotion of the efficiency of silicon-based solar cells through the absorption of solar radiation via quantum cutting. However, due to lack of ideal downconversion material, it is emergent to seek novel downconversion phosphors with large ultraviolet absorption and high quantum efficiency. Herein, we reported the photoluminescence performance and dynamics of a downconversion phosphor La2GeO5: Bi3+, Nd3+. This phosphor presents a strong ultraviolet absorption and emits a series of intense near infrared emissions by quantum cutting. The emission energy from the Nd3+ matches the energy gap of silicon-based solar cells which can improve the solar cell efficiency. Energy transfer from Bi3+ to Nd3+ in La2GeO5 occurs, proving that energy transfer mechanism of Bi3+ -> Nd3+ is an electric dipole-dipole (DMSO-d(6)) interaction. The energy transfer efficiency of Bi3+ -> Nd3+ and theoretical quantum efficiency for La2GeO5: Bi3+, Nd3+ are calculated to be as high as 91% and 191%, respectively. La1.92GeO5:0.03Bi(3+), 0.05Nd(3+) phosphor presents a promising thermal behavior with an activation energy of 0.152 eV. Thus, the development of near-infrared downconversion Bi3+, Nd3+ co-doped phosphors might open up a new approach to achieve high efficiency silicon solar cells by means of quantum cutting.