9:45 AM - 10:00 AM
[16a-303-4] Preparation of lead halide perovskite thick films and fundamental study of its optoelectric characteristics
Keywords:Photodiode, Perovskite, CH3NH3PbI3
A perovskite solar cell using lead methylammonium iodide (CH3NH3PbI3) as a photoactive layer is a new solar cell that can be manufactured by a simple and inexpensive solution process. Many researchers have demonstrated that perovskite solar cells exhibit a high energy conversion efficiency of more than 20%. And therefore, perovskite solar cells have attracted more attention in recent years. The properties of the perovskite solar cell are due to good semiconductive properties of a uniform and dense CH3NH3PbI3 thin film. On the other hand, since CH3NH3PbI3 can also produce crystals with a size of several mm square from the solution by recrystallization method, it is also interested in the properties of the crystal. In this report, we have fabricated CH3NH3PbI3 thick film exceeding hundreds of μm on FTO glass and verified the photoelectric characteristics.
First, a single crystal of CH3NH3PbI3 was synthesized by a reverse temperature recrystallization method. Following that the crystal was grinded into powder. Next, this powder was placed on a FTO glass on which a titanium oxide dense layer had been formed, γ-butyrolactone (GBL) was dropped to make the powder resolved, and the substrate was heated on a hot plate to volatilize the solvent By repeating this process, a thick film of perovskite having an electrode area of 3 mm × 3 mm was produced with a thickness of 50 μm to 400 μm. On the surface of the thick film of perovskite, gold was deposited as an electrode by evaporation.
Current-voltage characteristics were measured by light irradiation with an optical fiber of 3 mm Φ from the FTO glass surface and applying voltage stepwise with a source meter. Voltage of -21 V to 21 V was applied to the fabricated device, and current-voltage characteristics under dark and under monochromatic light irradiation (λ = 810 nm, 0.5 mW). The current under light irradiation on applying negative bias voltages remarkably increased with respect to the current under dark. This observation is considered to be relate to increase in the photoconductivity of CH3NH3PbI3 under negative bias voltage.
First, a single crystal of CH3NH3PbI3 was synthesized by a reverse temperature recrystallization method. Following that the crystal was grinded into powder. Next, this powder was placed on a FTO glass on which a titanium oxide dense layer had been formed, γ-butyrolactone (GBL) was dropped to make the powder resolved, and the substrate was heated on a hot plate to volatilize the solvent By repeating this process, a thick film of perovskite having an electrode area of 3 mm × 3 mm was produced with a thickness of 50 μm to 400 μm. On the surface of the thick film of perovskite, gold was deposited as an electrode by evaporation.
Current-voltage characteristics were measured by light irradiation with an optical fiber of 3 mm Φ from the FTO glass surface and applying voltage stepwise with a source meter. Voltage of -21 V to 21 V was applied to the fabricated device, and current-voltage characteristics under dark and under monochromatic light irradiation (λ = 810 nm, 0.5 mW). The current under light irradiation on applying negative bias voltages remarkably increased with respect to the current under dark. This observation is considered to be relate to increase in the photoconductivity of CH3NH3PbI3 under negative bias voltage.