Valastro Salvatore, Smecca Emanuele, Sanzaro Salvatore, Deretzis Ioannis, La Magna Antonino, Numata Youhei, Jena Ajay Kumar, Miyasaka Tsutomu, Gagliano Antonio, Alberti Alessandra
CNR-IMM, Catania, Italy.
Department of Electrical, Electronic and Computer Engineering, University of Catania, Catania, Italy.
Front Chem. 2020 Apr 17;8:200. doi: 10.3389/fchem.2020.00200. eCollection 2020.
Carbon-based top electrodes for hole-transporting-layer-free perovskite solar cells (PSCs) were made by hot press (HP) transfer of a free-standing carbon-aluminum foil at 100°C and at a pressure of 0.1 MPa on a methylammonium lead iodide (MAPbI) layer. Under these conditions, the perovskite surface was preserved from interaction with the solvent. Over a timescale of 90 days, HP-PSCs were systematically compared to reference cells with carbon-based top electrodes deposited by doctor blading (DB). We found that all the photovoltaic parameters recorded in HP-PSCs during time under ambient conditions settled on values systematically higher than those measured in the reference DB-PSCs, with efficiency stabilized at around 6% within the first few measurements. On the other hand, in DB-PSCs, a long-lasting (14 days) degrading transient of the performances was observed, with a loss of efficiency from an initial ~8% to ~3%. Moreover, in HP-PSCs, a systematic day-by-day recovery of the efficiency after operation was observed (Δ2%) by leaving the cell under open circuit, a nitrogen environment, and dark conditions. Noteworthily, a full recovery of all the parameters was observed at the end of the experiment, while DB-PSCs showed only a partial recovery under the same conditions. Hence, the complete release of solvent from the carbon contact, before an interface is established with the perovskite layer, offers a definite advantage through the long period of operation in preventing irreversible degradation. Our findings indeed highlight the crucial role of the interfaces and their feasible preservation under nitrogen atmosphere.
用于无空穴传输层钙钛矿太阳能电池（PSC）的碳基顶部电极是通过在100°C和0.1 MPa压力下将自支撑碳铝箔热压（HP）转移到甲基碘化铅（MAPbI）层上制成的。在这些条件下，钙钛矿表面得以避免与溶剂相互作用。在90天的时间范围内，将热压PSC与通过刮刀涂布（DB）沉积碳基顶部电极的参考电池进行了系统比较。我们发现，在环境条件下，热压PSC记录的所有光伏参数稳定在系统上高于参考刮刀涂布PSC测量值的值，效率在前几次测量中稳定在约6%左右。另一方面，在刮刀涂布PSC中，观察到性能出现了持续较长时间（约14天）的降解瞬态，效率从初始的约8%下降到约3%。此外，在热压PSC中，通过将电池置于开路、氮气环境和黑暗条件下，观察到运行后效率每天都有系统的恢复（约2%）。值得注意的是，在实验结束时观察到所有参数都完全恢复，而刮刀涂布PSC在相同条件下仅部分恢复。因此，在与钙钛矿层建立界面之前，从碳接触中完全释放溶剂，在长期运行中防止不可逆降解方面具有明显优势。我们的研究结果确实突出了界面的关键作用以及它们在氮气气氛下的可行保存。
