Photovoltaic Characteristics of CH3NH3PbI3 Perovskite Solar Cells Added with Ethylammonium Bromide and Formamidinium Iodide

Abstract

Photovoltaic characteristics of solar cell devices in which ethylammonium (EA) and formamidinium (FA) were added to CH3NH3PbI3 perovskite photoactive layers were investigated. The thin films for the devices were deposited by an ordinary spin-coating technique in ambient air, and the X-ray diffraction analysis revealed changes of the lattice constants, crystallite sizes and crystal orientations. By adding FA and EA, surface defects of the perovskite layer decreased, and the photoelectric parameters were improved. In addition, the highly (100) crystal orientations and device stabilities were improved by the EA and FA addition.

Development of Polysilane-Inserted Perovskite Solar Cells

“…A polysilane solution was prepared by mixing chlorobenzene (Fujifilm Wako Pure Chemical Corporation, 0.5 mL) with DPPS (Osaka Gas Chemicals, Osaka, Japan, OGSOL SI-30-10, 10 mg). During the last 15 s of the third spin-coating of the perovskite precursor solutions, the DPPS polysilane solution was also spin-coated on the perovskite layer [24]. The prepared cells were then annealed at 180 and 200 °C for 10 min, and at 220 °C for 5 min in ambient air.…”

“…To increase the t-factor and reduce the migration of MA, formamidinium (FA: CH3(NH2)2) with a larger ionic radius (2.53 Å ) than MA (2.17 Å ) was doped at the MA site, and the stabilities of the perovskite solar cells were improved by FA addition [21,22]. Studies on devices with ethylammonium (EA: CH3CH2NH3) [23,24] or guanidinium (GA: C(NH2)3) [25,26] addition to perovskites have also been reported. EA and GA have larger ionic radii (2.74 and 2.78 Å ) than MA, and the addition of EA or GA can be expected to improve the structural stability from the viewpoint of the tolerance factors [19] and structural calculations [27,28].…”

“…Then, EA or GA addition to the perovskite compounds provided surface coatings with fewer defects, highly (100)-oriented crystals, and improved stability of the devices [24,26]. However, it should be noted that excessive addition of EA leads to phase separation, a decrease in crystallinity, and precipitation of PbI2 as an impurity [30].…”

Polysilane-Inserted Methylammonium Lead Iodide Perovskite Solar Cells Doped with Formamidinium and Potassium

“…To increase the t-factor and reduce the migration of MA, formamidinium (FA: CH 3 (NH 2 ) 2 ) with a larger ionic radius (2.53 Å) than MA (2.17 Å) was doped at the MA site, and the stabilities of the perovskite solar cells were improved by FA addition [31][32][33]. Studies on devices with ethylammonium (EA: CH 3 CH 2 NH 3 ) [34,35] or guanidinium (GA: C(NH 2 ) 3 ) [36,37] addition to perovskites have also been reported. EA and GA have larger ionic radii (2.74 and 2.78 Å) than MA, and the addition of EA or GA can be expected to improve the structural stability from the viewpoint of the tolerance factors [27] and structural calculations [38,39].…”

Electronic Structures, Spectroscopic Properties, and Thermodynamic Characterization of Alkali Metal and Transition Metal Incorporated Perovskite Crystals by First-Principles Calculation

“…The perovskite crystals are constructed with lead (Pb) atom at B-site, halogen anions at X-site, and organic cation such as methyl ammonium (MA: CH3NH3), formamidinium (FA: CH3(NH2)2), ethylammonium (EA: CH3CH2(NH2)2) and guanidinium (GA: C(NH2)3) at A-site. Partial substitution of organic cation with alkali metal ion (lithium, sodium, potassium, rubidium, and cesium) at A-site [5][6][7][8], lead metal, transition metal (tin, copper, cobalt, nickel, and chromium) [9][10][11] at B-site, and halogen anion (iodine, chloride, and bromide) at X-site in the cubic crystal was performed for improving the photovoltaic performance and long-term stability. Especially, correlative relationship between the photovoltaic and optical properties, and electronic structure was discussed on the basis of experimental results and quantum calculation.…”