Stabilization of Intrinsic Ions in Perovskite Solar Cells by Employment of a Bipolar Star-Shaped Organic Molecule as a Charge Transport Buffer

Abstract

The stability of perovskite thin films is one of the most critical challenges for their practical application in photovoltaic devices. The defects of hybrid organic−inorganic perovskites, such as the photogenerated Pb 0 and iodine (I 0 ), will cause lattice distortion and act as recombination centers, which will also make the photovoltaic behavior worse. Introducing properly designed additives might minimize this harmful mechanism. The designed molecule core calix[4]resorcinarene (CRA)−triphenylamine (TPA) that contains hole transport functional groups (TPA) and electron transport functional groups (triazole) has been synthesized and employed as an additive in the perovskite, where it serves as an adjust buffer of charge transport. We found that this novel molecule improves the crystallization of triplecation perovskite films. The power conversion efficiency of 18.5% of the control device is increased to 20.0% by introducing a proper amount of CRA−TPA. The defect density of the perovskite layer has been substantially decreased to ≈1/4 with the introduction of the designed additives, with stability benefiting as well.

The evolution of triphenylamine hole transport materials for efficient perovskite solar cells

“…Notably, the PCE of 18.5% measured for the control device was increased to 20.0% by introducing an optimal amount of CRA-TPA. 117 2.5.2. Star-shaped compounds with tetra-arm (X-shaped) structures.…”

“…Notably, the PCE of 18.5% measured for the control device was increased to 20.0% by introducing an optimal amount of CRA-TPA . 117…”

“…Fig.29The organic molecule CRA-TPA was introduced into a solution of a triple-cation perovskite precursor, where it serves as an adjusted buffer for charge transport. Reproduced from ref 117. with permission from the American Chemical Society, copyright 2020.…”

p-Type Polymers for Templated Crystallization of Perovskite Films and Interface Optimization for High Performance Solar Cells

“…These conjugated polymers could also help to realize ultrafast charge transfer at the interface due to the cascade energy level landscape. Furthermore, ionic migration at the interface of PSCs limits the efficiency of PSCs [8][9][10][11]. Ion migration, either to the perovskite/electron transport layer (ETL) or perovskite/hole transport (HTL) interfaces, may result in undesirable reactions between I − and the transport layers or metal electrode.…”