Investigation on guanidinium bromide incorporation in methylammonium lead iodide for enhanced efficiency and stability of perovskite solar cells

Physics-driven discovery and bandgap engineering of hybrid perovskites

“…This leads to a gradual blue shi of the PL peak. 43,62 This decrease in intensity can possibly be attributed to various reasons such as the crystal structure evolution where the mixed-halide system can have halide rich regions that can create non-radiative recombination pathways. 63,64 Also as the bromide content increases, the bandgap widens which can impact the PL intensity.…”

“…66 MAPbI 3 has a tolerance factor of ∼0.8, while that of GAPbBr 3 is calculated to be ∼1.4. 67 This suggests that pure GA lead bromide crystallizes in a lower-dimensional perovskite structure. In addition to the tolerance factor, the octahedral factor (m) is also relevant for the formation of the perovskite structure.…”

“…In our case, when the I − (r avg ∼ 198 pm) is replaced by the Br − ion (r avg ∼ 185 pm), which is smaller than I − , it results in an increase of the octahedral factor. 67 However, this also implies that the decrease in the halogen ion size reduces the BX 6 octahedral size accommodating the larger GA cation in the MAPbI 3 lattice.…”

“…42 The r A of GA (278 pm) 17 is larger than that of MA (217 pm), 41 which reduces crystal distortion and increases the tolerance factor, resulting in improved long-term stability. 40,41,43 Synthesis methods can be broadly categorized into manual and high-throughput approaches. Manual synthesis involves hand-craed processes, oen resulting in the creation of one sample at a time.…”

Effects of Co-Addition of Guanidinium and Cesium to CH3NH3PbI3 Perovskite Solar Cells

“…The carrier lifetime and the surface morphology were improved by introducing guanidinium bromide (GABr) in MAPbI 3 . The conversion efficiency of the device with 10% GABr showed less hysteresis than that of MAPbI 3 [32], and the conversion efficiency was stable after a continuous irradiation of light for 400 h. The dynamics of multiple organic cations, including GA, were also discussed quantitatively [33], which indicated that relationship between organic cations and perovskite properties could provide a guideline for the high-efficiency perovskite solar cells. The effects of a surface treatment with guanidinium iodide (GAI) were also reported [34], which showed that the treatment with 10 mg mL −1 GAI solution removed excess PbI 2 and the crystallinity and grain sizes were improved.…”