Efficient Perovskite Solar Cells with Cesium Acetate-Modified TiO₂ Electron Transport Layer

The photovoltaic performance of perovskite solar cells (PSCs) is still below the Shockley–Queisser limit due to the impact of defects originated from the surface and the bulk of the perovskite. Hence, it is particularly important to alleviate non-radiative losses in the solar cell by employing an interface modification strategy. We implemented TiO2/CsAC as an electron transport layer to achieve high-performance devices based on diethylammonium bromide (DABr)-doped MAPbI3. The critical role of cesium acetate (CsAC) is designed to improve perovskite crystallization and achieve a high-quality interfacial contact between TiO2 and the perovskite layer. TiO2/CsAC promotes the shift of Br ions to form the Br-rich region at the perovskite/HTL interface simultaneously, which can enhance the extraction of holes and block the diffusion of electrons. Attributing to the modification of CsAC to TiO2, the performance of DABr-doped MAPbI3 PSC is improved significantly

Self-Assembled TiO₂ Nanorods as Electron Extraction Layer for High-Performance Inverted Polymer Solar Cells

We demonstrate the use of TiO₂ nanorods with well-controlled lengths as excellent electron extraction materials for significantly improving the performance of inverted polymer solar cells. The cells containing long nanorods outperform the devices using amorphous TiO₂ particles as the electron extraction layer, mainly by a 2-fold increase in short-circuit current and fill factor. The enhanced charge extraction is attributed to the high electron mobility in crystalline nanorods and their preferential alignment during film formation. Furthermore, transient photocurrent studies suggest the presence of fewer interfacial and internal defects in the nanorod interlayers, which can effectively decrease carrier recombination and suppress electron trapping