Hybrid inorganic-organic perovskites are emerging semiconductors for optoelectronic applications. Two-dimensional (2D) perovskites have shown great potential due to their diverse structures, high tunabilities and superior performance in solar cells and light-emitting diodes (LEDs). Here, we demonstrate the syntheses and characterization of two new series of hybrid 2D perovskites which belong to the Dion–Jacobson (DJ) structure type. The DJ perovskites have a general formula of A′An–1PbnI3n+1 (A′ = 3-(aminomethyl)piperidinium (3AMP) or 4-(aminomethyl)piperidinium (4AMP), A = methylammonium (MA)). Different from the Ruddlesden−Popper (RP) phases, which have two layers of organic spacers due to the 1+ charge, the DJ perovskites only have a single layer of the organic spacers in between the inorganic sheets, resulting in much smaller interlayer distance. Switching the protonation site on the organic cation form 3’ to 4’, the optical properties change dramatically, where the 3AMP series has smaller band gaps than the 4AMP series. The origin of the difference comes from the Pb-I-Pb angles, where 3AMP series has larger Pb-I-Pb angles (less distorted). With the more preferred optical properties of the 3AMP series, we fabricate solar devices based on both series, which (3AMP)(MA)3Pb4I13 has the best power conversion efficiency (PCE) of 7.32%, as expected much higher than the corresponding (4AMP)(MA)3Pb4I13. The structure-property relationship within this system highlights the importance of the choice of organic cations and how they influence the overall properties of the materials.

Hybrid 2D Dion–Jacobson perovskites and application in solar cells

256th National Meeting (2018)

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