Abstract:
Counter electrodes (CEs) of perovskite solar cell (PSC) are usually prepared by thermal evaporation of noble metals such as Au or Ag under high vacuum condition. The replacement of costly metallic CEs by carbon material has attracted recent attentions to lower the price of this kind of high-efficiency bulk heterojunction photovoltaic cell based on organometallic-halide perovskite light harvester. This research has investigated the synthesis of graphene by exfoliated electrochemical method which was conducted by applying bias voltage in range of 08 V to the pure graphite electrodes submerged in the 0.5 M sulfuric solution. The graphene powder having surface resistance of 7.47 ohm/square was obtained with high carbon-content as confirmed by XRD and SEM results. PSC test devices were fabricated on FTO glass substrate layer-by-layer printed with different types of materials in following order: anti-recombining layer / electron transport layer / insulating layer / hole transport medium / carbon materials as counter electrode. The results showed that the mixed graphene and carbon black with weight ratio of 1:0.25 as counter electrode give better PSC performance than the pure graphene. In addition, PSC devices based on the mixture of formamidinium (HN=CHNH3+, FA) and methylammonium (CH3NH3+, MA) cations (3 : 2 mole ratio) in the A position of the APbI3 perovskite structure exhibit higher photoconversion efficiency (PCE) compared to those made from only FA or MA alone. Finally the PSC device having NiO as hole transport material layer in between ZrO2 insulating layer and carbon counter electrode shows the best performance of JSC = 12.04 mA/cm2, VOC = 0.83 V, Fill Factor = 24.84% and PCE = 2.60%.