g-Chiang Chen

Annealing Effect on (FAPbI3)1−x(MAPbBr3)x Perovskite Films in Inverted-Type Perovskite Solar Cells

This study determines the effects of annealing treatment on the structure and the optical and electronic behaviors of the mixed (FAPbI3)1−x(MAPbBr3)x perovskite system. The experimental results reveal that (FAPbI3)1−x(MAPbBr3)x (x ~ 0.2) is an effective light-absorbing material for use in inverted planar perovskite solar cells owing to its large absorbance and tunable band gap. Therefore, good band-matching between the (FAPbI3)1−x(MAPbBr3)x and C60 in photovoltaic devices can be controlled by annealing at various temperatures. Accordingly, an inverted mixed perovskite solar cell with a record efficiency of 12.0% under AM1.5G irradiation is realized.

Fabrication and characteristics of CH3NH3PbI3 perovskite solar cells with molybdenum-selenide hole-transport layer

We present a solar cell with an FTO/MoSe2/perovskite/C60/bathocuproine (BCP)/silver structure. The hole-transport material (HTM), active photovoltaic layer, electron-transport layer, and electron-buffer layer were made of MoSe2, perovskite, C60, and BCP, respectively. The domain sizes of the CH3NH3PbI3 (MAPbI3) perovskite films that were deposited on the MoSe2 HTM films following annealing at 500, 600, and 700 °C were determined to be 23, 25, and 27 nm, respectively, revealing that the domain size of the MAPbI3 perovskite film increased with the annealing temperature of the MoSe2 HTM film under it. Therefore, the crystallinities of the perovskite layers were improved by increasing the annealing temperatures of the HTM layers. Following optimization, the maximum power-conversion efficiency was 8.23%.

A newly developed lithium cobalt oxide super hydrophilic film for large area, thermally stable and highly efficient inverted perovskite solar cells

A new inorganic hole transporting layer, a sputtering made LiCoO2 film, was developed and used in an inverted perovskite solar cell (PSC) and sub-module (PSM). The LiCoO2 film prepared by RF magnetron sputtering is composed of nano-sized particles and a superhydrophilic surface after treating it with UV–ozone, and therefore can be wetted evenly with a (MAI + PbI2)/(DMF + DMSO) precursor solution. By applying chlorobenzene as an anti-solvent, a very dense film with big perovskite grains was formed. After depositing the C60 electron transporting layer, BCP hole blocking layer and Ag electrode, the best perovskite solar cell achieves a power conversion efficiency (PCE) of 19% with negligible current hysteresis. The high-efficiency cell is stable up to 90 °C in the inert atmosphere without encapsulation, and the PCE only decreases by 2% when the cell was heated at 100 °C for 30 minutes. When the cell was heated at 100 °C for 5 days, the PCE decreases by only 40%; nevertheless, under the same heating conditions, the efficiency of the PSC based on the PEDOT:PSS HTL is lost totally. The superhydrophilic surface of LiCoO2 made the even wetting of the large surface area with the perovskite precursor solution possible. Therefore the perovskite solar sub-module with an active area of 25.2 cm2 (on a 10 cm × 10 cm substrate) can be fabricated to achieve a power conversion efficiency of 16% which was further verified to be 15%. The high-efficiency sub-module based on the LiCoO2 HTL also shows good thermal stability, and ca. 10% of the efficiency was lost by heating at 100 °C for 30 minutes. The development of new inorganic hole transporting layers for large area, thermally stable and highly efficient perovskite solar sub-modules closes the gap for their near-future market exploitation.