Fabrication, characterization and simulation analysis of perovskite solar cells with dopant-free solution-processible C6PcH₂ hole transporting material

A new design of perovskite solar cells (PSCs) with non-peripherally substituted octahexylphthalocyanine (C6PcH₂) hole transporting material (HTM) and MoO_x buffer layer was introduced through experiment and simulation analysis. The external quantum efficiency (EQE) and current density–voltage (JV) characteristics were performed to analyze the photovoltaic performance of the PSCs based on C6PcH₂ HTMs. The EQE was over 73% within the visible region (at 450 nm) but lower at 740 nm due to parasitic light absorption of C6PcH₂ molecules. As a result, a short-circuit current density (J_sc) J_sc = 16.3 mA/cm², open-circuit voltage (V_oc) V_oc = 0.95 V, fill factor (FF) FF = 35%, and a power conversion efficiency PCE = 5.4% were recorded under reverse bias scans (from open-circuit to short-circuit). Simulation analysis with Silvaco and SCAPS-1D was also performed to support the carrier transport analysis of PSCs with C6PcH₂ HTM as well their photovoltaic performance in temperature range from 303 to 258 K, in which the charge carrier mobility of C6PcH₂ molecules were strongly improved. By reducing the temperature from 303 to 258 K, the simulated PCE of 19.6% was achieved for the PSCs utilizing C6PcH₂ as an HTM. The difference in PCEs between the synthesized and simulated devices was in part due to the alignment of C6PcH₂ molecules in thin film. The simulation results closely supported the experiment and promised an improved performance upon realizing unknown electro-optical semiconductor properties of the C6PcH₂ layer.