A series of porphyrins as interfacial materials for inverted perovskite solar cells

Interface materials can improve the photovoltaic performance of the hybrid organic-inorganic perovskite solar cells (PSCs). Here, a series of porphyrin derivatives (metalloporphyrins: MTPPS₄, M = Zn²⁺, Cu²⁺, Co²⁺, Ni²⁺; free base porphyrin: TPPS₄) were developed to act as interfacial materials in PSCs. The introduction of porphyrin interlayers between PEDOT:PSS and perovskite layer in the inverted PSCs not only made energy level more matching but also improved the quality of the perovskite layer. Compared with the control device without an interlayer, the maximum power conversion efficiencies (PCE) of devices with the interlayers (in the order of ZnTPP₄, CuTPP₄, CoTPP₄, NiTPP₄ and TPP₄) were increased by 23%, 25%, 21%, 17% and 13%, respectively. The highest PCE of 14.61% was based on the CuTPPS₄-modified device. The porphyrins acted as the interlayers to promote carrier transport and reduce charge recombination at the interface, resulting in the increase of open-circuit voltage (V_OC), short-circuit current density (J_SC) and fill factor (FF).