Analysis of electrical parameters of p-i-n perovskites solar cells during passivation via N-doped graphene quantum dots

Abstract

Metal halide perovskite (PVSK) solar cells (PSCs) have arisen as emerging photovoltaics (PV) technology. Nevertheless, due to defects in the organic-inorganic metal-halide PVSK layer, the conversion efficiency (η) and the stability are hampered. Thus, the passivation of the perovskites layer is vital to obtain stable PSCs against temperature and humidity. Due to the introduction of the N-doped graphene quantum dots (NGQDs) interlayer at the PVSK/electron transport layer (ETL) interface, recombination in the PSCs is greatly suppressed. The NGQDs layer promotes charge transportation in the PVSK layer as well as at the PVSK/ETL interface, which enhances the performance of the PSCs. The performance of the PSCs is governed by the cell's electrical parameters.Thus, the electrical parameters are analyzed during PSC passivation. PVSK passivation with NGQDs consequences in the upsurge of the recombination lifetime (from 31.7 to 59.9 ns), improves the interfacial charge transfer and suppresses the trap density from 5.53×1016 cm−3 to 4.68×1016 cm−3, which are confirmed through photoluminescence, electrochemical impedance spectroscopy (EIS) and space charge limited (SCL) measurement, respectively. The conversion efficiency of the NGQDs passivated PSC is boosted to 17.10%, which is ∼13.8% higher than the control cell (η ∼15.03%, un-passivated PSC). Furthermore, the PV cell parameters are determined analytically, which revealed that both the ideality factor (n) and leakage current (J0) reduced to 1.2409 and 1.37 × 10−16 A/cm2, respectively (n = 1.6114 and J0 = 4.24 × 10−13 A/cm2 of the control cell). The present work synergically improves the charge transport and suppresses the non-radiative recombination losses in PSCs via defect passivation through NGQDs which are essential for further advancement of the device performance and operational stability.