Morphological tuning and defect-free lead halide perovskite by surface passivation for solar cell fabrication

Perovskite solar cells (PSCs) evolved as a third-generation photovoltaic technology device due to their flexible tunability of optoelectronic properties, low-cost fabrication protocols, with remarkable power conversion efficiency to compete with the present solar cell market. However, interfacial and deep-level defects in the perovskite layer limit the devices’ power conversion efficiency (PCE). Additive engineering is one of the most holistic approaches to overcoming these issues. In this article, we report the additive engineering of the perovskite layer with cellulose-based synthetic additive hydroxypropyl methylcellulose (HPMC) to investigate its optical absorption, surface morphology, and electrical performances. Herein, we fabricated a solar cell layer architecture consisting of FTO/mesoscopic TiO2/MAPbI3/carbon/Ag. Optical, morphological, and structural properties were examined via UV-Vis spectroscopy, field emission scanning electron microscopy, and X-ray diffraction analyses. Furthermore, photoluminescence (PL) spectra were analyzed to investigate the lifetime of the photogenerated charge carrier. Moreover, the interaction between the functional groups of HPMC and with perovskite precursor solution was characterized via Fourier-transform infrared spectroscopy (FTIR). Finally, the electrical performance of the solar cells was analyzed under simulated AM 1.5G solar illumination using 100 mW.cm–2 light intensity. The surface morphology of the perovskite solar cell was modified by incorporating HPMC additive into the perovskite. This HPMC additive-based perovskite showed improved PCE compared to a non-HPMC-based perovskite device. Moreover, the HPMC additive perovskite device improves film morphology with 13.37% of PCE and low hysteresis behavior. This method provides a facile route to fabricate low-defect PSCs through a low-cost solution processed at room temperature with the help of defect-minimized coherent interfaces.