Heterointerface Energetics Regulation Strategy Enabled Efficient Perovskite Solar Cells

In the domain of perovskite photovoltaics, the heterointerfaces are subject to substantial trap-assisted non-radiative recombination, predominantly attributed to the energy offset, interface defects, and the roughness of the contact. This phenomenon at the heterointerfaces, where carrier non-radiative recombination and energy dissipation occur due to defects and suboptimal energy level alignment, can be principally held accountable for the Voc losses. Herein, a heterointerface energetics regulation (HER) strategy is proposed by introducing potassium trifluoroacetate (KTFA) in the perovskite precursor solution to eliminate the trap defects and optimize surface potential and Fermi level. It is first demonstrated that non-doping K+ but precipitating at the upper and buried perovskite will improve energy-level alignment for charge extraction dynamics. In addition, the TFA- exhibits strong electrostatic force with undercoordinated Pb2+ in the buried contact of perovskite and Sn4+ in the SnO2 electron transporting layer. Based on the vacuum flash evaporation green treatment without anti-solvent, the Rb0.02(Cs0.05FA0.95)0.98PbI0.91Br0.03Cl0.06 and Cs0.05FA0.95PbI3 based device can achieve maximum efficiency of 23.36% and 24.48%, respectively. Further, the modified devices exhibit 92% initial efficiency output after 1200 h of aging. HER strategy for addressing interface defects and bandgap alignment are poised to advance both the performance and stability of perovskite solar cells. A heterointerface energetics regulation strategy by introducing potassium trifluoroacetate in the perovskite precursor solution to eliminate the trap defects and optimize surface potential and Fermi level, is proposed. Utilizing TOF-SIMS, potassium is challenging to dope into the perovskite lattice but accumulates at both the upper surface and buried interface of the perovskite for reducing VOC losses of perovskite solar cells.image