RESUMO
Perovskite solar cells have emerged as a potential energy alternative due to their low cost of fabrication and high power conversion efficiency. Unfortunately, their poor ambient stability has critically limited their industrialization and application in real environmental conditions. Here, we show that by introducing hexamine molecules into the perovskite lattice, we can enhance the photoactive phase stability, enabling high-performance and air-processable perovskite solar cells. The unencapsulated and freshly prepared perovskite solar cells produce a power conversion efficiency of 16.83% under a 100 mW cm-2 1.5G solar light simulator and demonstrate high stability properties when being stored for more than 1500 h in humid air with relative humidity ranging from 65 to 90%. We envisage that our findings may revolutionize perovskite solar cell research, pushing the performance and stability to the limit and bringing the perovskite solar cells toward industrialization.
RESUMO
The crystallinity properties of perovskite influence their optoelectrical performance in solar cell applications. We optimized the grain shape and crystallinity of perovskite film by annealing treatment from 130 to 170 °C under high humidity (relative humidity of 70%). We found that the grain size, grain interface, and grain morphology of the perovskite are optimized when the sample was annealed at 150 °C for 1 h in the air. At this condition, the perovskite film is composed of 250 nm crystalline shape grain and compact inter-grain structure with an invincible grain interface. Perovskite solar cells device analysis indicated that the device fabricated using the samples annealed at 150 °C produced the highest power conversion efficiency, namely 17.77%. The open circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF) of the device are as high as 1.05 V, 22.27 mA/cm2, and 0.76, respectively. Optoelectrical dynamic analysis using transient photoluminescence and electrochemical impedance spectroscopies reveals that (i) carrier lifetime in the champion device can be up to 25 ns, which is almost double the carrier lifetime of the sample annealed at 130 °C. (ii) The interfacial charge transfer resistance is low in the champion device, i.e., ~20 Ω, which has a crystalline grain morphology, enabling active photocurrent extraction. Perovskite's behavior under annealing treatment in high humidity conditions can be a guide for the industrialization of perovskite solar cells.
RESUMO
This study investigated the effectiveness of heat shield placement locations during the rework process to avoid thermal and mechanical damage to adjacent ball grid array components and their solder joints on double-sided printed circuit board assembly. Three types of heat shield placement locations were used: sample X, individual heat shield placement on adjacent components of the rework location; sample Y, a U-shaped, and sample Z, a square-shaped heat shield placed respectively at the heat source location. The dye and pull test results, infrared thermography, and temperature measurements were analysed to understand the relationship between the location of the heat shield and solder joint damage during rework. Heat shield placement at the heat source location on the reworked component can reduce the peak temperatures on the adjacent rework component locations by up to 8.18%. The peak temperatures of the centre and corner of the BGA component can be maintained below 195 °C and 210 °C, respectively to improve the adjacent rework component locations' solder joint quality by reducing solder joint damage by more than 50% solder cracks. This is useful for thermal management during rework involving high-density ball grid array component placements on double-sided printed circuit board assembly.
