RESUMO
Atomic layer deposition (ALD) growth of conformal thin SnOx films on perovskite absorbers offers a promising method to improve carrier-selective contacts, enable sputter processing, and prevent humidity ingress toward high-performance tandem perovskite solar cells. However, the interaction between perovskite materials and reactive ALD precursor limits the process parameters of ALD-SnOx film and requires an additional fullerene layer. Here, it demonstrates that reducing the water dose to deposit SnOx can reduce the degradation effect upon the perovskite underlayer while increasing the water dose to promote the oxidization can improve the electrical properties. Accordingly, a SnOx buffer layer with a gradient composition structure is designed, in which the compositionally varying are achieved by gradually increasing the oxygen source during the vapor deposition from the bottom to the top layer. In addition, the gradient SnOx structure with favorable energy funnels significantly enhances carrier extraction, further minimizing its dependence on the fullerene layer. Its broad applicability for different perovskite compositions and various textured morphology is demonstrated. Notably, the design boosts the efficiencies of perovskite/silicon tandem cells (1.0 cm2) on industrially textured Czochralski (CZ) silicon to a certified efficiency of 28.0%.
RESUMO
Exploring strategies to control the crystallization and modulate interfacial properties for high-quality perovskite film on industry-relevant textured crystalline silicon solar cells is highly valued in the perovskite/silicon tandem photovoltaics community. The formation of a 2D/3D perovskite heterojunction is widely employed to passivate defects and suppress ion migration in the film surface of perovskite solar cells. However, realizing solution-processed heterostructures at the buried interface faces solvent incompatibilities with the challenge of underlying-layer disruption, and texture incompatibilities with the challenge of uneven coverage. Here, a hybrid two-step deposition method is used to prepare robust 2D perovskites with cross-linkable ligands underneath the 3D perovskite. This structurally coherent interlayer benefits by way of preferred crystal growth of strain-free and uniform upper perovskite, inhibits interfacial defect-induced instability and recombination, and promotes charge-carrier extraction with ideal energy-level alignment. The broad applicability of the bottom-contact heterostructure for different textured substrates with conformal coverage and various precursor solutions with intact properties free of erosion are demonstrated. With this buried interface engineering strategy, the resulting perovskite/silicon tandem cells, based on industrially textured Czochralski (CZ) silicon, achieve a certified efficiency of 28.4% (1.0 cm2 ), while retaining 89% of the initial PCE after over 1000 h operation.
RESUMO
The Ca3SiO5 : Eu2+ phosphor was synthesized by the sol-gel reaction method. The emission spectrum was measured by a SPEX1404 spectrophotometer, and the excitation spectrum was measured by a SHIMADZU RF-540 ultraviolet spectrophotometer. All the characterization of the phosphors was conducted at room temperature. The results show that the emission spectrum of Ca3SiO5 : Eu2+ phosphor exhibits one asymmetry band centred at 505 nm under the 365 nm excitation, and the excitation spectrum for 505 nm indicates two bands centred at 374 and 397 nm, respectively. The above results indicate that the phosphor used for w-LEDs can be excited by UV light, and emit green light. The effect of synthesis condition, such as synthesis temperature, synthesis time and Eu2+ concentration, on the emission spectrum of Ca3SiO5 : Eu2+ phosphor was investigated. The results show that the emission peak intensity of Ca3SiO5 : Eu2+ phosphor firstly increases, then decreases with the increase in synthesis temperature or synthesis time or Eu2+ concentration, and reaches the maximum value at 1,100 degrees C, for 4 h and 0.5 mol% Eu2+.
