Impact of methylammonium lead trihalide absorbing layers on performance efficiency of manganese dioxide passivated perovskite solar cells

The occurrence of structural defects such as dangling bond and vacancies at grain boundaries (GBs) promote defect−mediated non−radiative recombination of the photogenerated electron-hole pairs at the trap sites of perovskites. As such, functionalizing GBs in the crystal reduces recombination loss, and thus improve perovskite solar cell (PSC) overall photovoltaic performance. Here, organic−inorganic methylammonium lead iodide dibromide, \\({\\text{C}}{{\\text{H}}_3}{\\text{N}}{{\\text{H}}_3}{\\text{Pb}}{\\left[ {{{\\text{I}}_{1 - 0.66}}{\\text{B}}{{\\text{r}}_{0.66}}} \\right]_3},\\) was synthesized via solution-based processing and modified with manganese dioxide ( \\({\\text{Mn}}{{\\text{O}}_2}\\) ). Besides, the impact of replacement of Bromine (Br) with Iodine (I) anion on the structural, morphological and optical properties using X-Ray Diffraction (XRD), Scanning electron microscopy (SEM) and Ultraviolet-visible spectrophotometry was investigated. The characterization studies showed enhanced intensity of the perovskites’most prominent diffraction peaks, improved microstructural features, right-shifting displacement of absorption edge, energy bandgap reduction (1.99–1.77 eV), optical reflectivity attenuation and improved photoconductivity with \\({\\text{Mn}}{{\\text{O}}_2}\\) inclusion and total replacement of Br with I anion in \\({\\text{C}}{{\\text{H}}_3}{\\text{N}}{{\\text{H}}_3}{\\text{Pb}}{\\left[ {{{\\text{I}}_{1 - 0.66}}{\\text{B}}{{\\text{r}}_{0.66}}} \\right]_3}\\) crystal lattice. Performance parameters such as power conversion efficiency (PCE), fill factor (FF), open circuit voltage (Voc) and short circuit current (Jsc) were also evaluated. The PCE values of 8.79%, 9.75% and 10.39%, Jsc values of 16.24 mAcm − 2 , 17.10 mAcm − 2 and 18.50 mAcm − 2 , FF values of 53.12%, 55.41% and 54.70%, and Voc values of 1.02 V, 1.03 V and 1.06 V, were obtained for ITO/rGO/TiO 2 / \\({\\text{C}}{{\\text{H}}_3}{\\text{N}}{{\\text{H}}_3}{\\text{Pb}}{\\left[ {{{\\text{I}}_{1 - 0.66}}{\\text{B}}{{\\text{r}}_{0.66}}} \\right]_3} - {\\text{Mn}}{{\\text{O}}_2}\\) /Graphite, ITO/rGO/TiO 2 \\(/{\\text{C}}{{\\text{H}}_3}{\\text{N}}{{\\text{H}}_3}{\\text{Pb}}{\\left[ {{{\\text{I}}_{1 - 0.33}}{\\text{B}}{{\\text{r}}_{0.33}}} \\right]_3} - {\\text{~Mn}}{{\\text{O}}_2}/\\) Graphite and ITO/rGO/TiO 2 / \\({\\text{C}}{{\\text{H}}_3}{\\text{N}}{{\\text{H}}_3}{\\text{Pb}}{\\left[ {{{\\text{I}}_{1 - 0}}{\\text{B}}{{\\text{r}}_0}} \\right]_3} - \\) \\({\\text{Mn}}{{\\text{O}}_2}\\) /Graphite devices, respectively. The percentage enhancement values of 9.84% and 15.39% were determined for ITO/rGO/TiO 2 \\(/{\\text{C}}{{\\text{H}}_3}{\\text{N}}{{\\text{H}}_3}{\\text{Pb}}{\\left[ {{{\\text{I}}_{1 - 0.33}}{\\text{B}}{{\\text{r}}_{0.33}}} \\right]_3} - {\\text{~Mn}}{{\\text{O}}_2}/\\) Graphite and ITO/rGO/TiO 2 / \\({\\text{C}}{{\\text{H}}_3}{\\text{N}}{{\\text{H}}_3}{\\text{Pb}}{\\left[ {{{\\text{I}}_{1 - 0}}{\\text{B}}{{\\text{r}}_0}} \\right]_3} - {\\text{Mn}}{{\\text{O}}_2}\\) /Graphite devices compared to ITO/rGO/TiO 2 / \\({\\text{C}}{{\\text{H}}_3}{\\text{N}}{{\\text{H}}_3}{\\text{Pb}}{\\left[ {{{\\text{I}}_{1 - 0.66}}{\\text{B}}{{\\text{r}}_{0.66}}} \\right]_3} - {\\text{Mn}}{{\\text{O}}_2}\\) /Graphite device. This study shows that \\({\\text{Mn}}{{\\text{O}}_2}~\\) inclusion into perovskite and total replacement of Br with I anion synergistically promoted enhancement of grain growth of the film and impact the photovoltaic response of the fabricated PSCs.