High specific power encapsulation technology for flexible triple-junction solar cells with extreme environmental reliability

In space applications, the extreme and rapid temperature fluctuations will lead to flexible Ⅲ-Ⅴ multi-junction solar cell modules undergoing repeated thermal cycling at interconnection joints and encapsulation interfaces. This generates thermal and mechanical stresses that result in fatigue, delamination and cracking, which are the primary failure mechanisms of modules. In this work, a highly reliable encapsulation method for flexible triple-junction solar cell modules is proposed using micro-coated electrically conductive adhesive interconnects and lightweight film packaging structures, achieving a flexible GaInP/GaAs/InGaAs solar cell module with a bending radius of 2 cm and a specific power of 1155.38 W/kg under AM0 spectrum. Extreme environmental reliability tests were conducted to assess the module’s durability under application conditions, including temperature cycling, damp heat, low-pressure temperature cycling and temperature shock. The experimental results showed that the performance losses of flexible modules were only 0.74% (−60 ℃ to 75 ℃, 204 cycles), 2.68% (85 ℃, 85%RH, 502 h), 1.09% (−70 ℃ to 90 ℃, 5 kPa, 5 cycles) and 1.54% (−180 ℃ to 100 ℃, 50 cycles) respectively. Thus, these results confirm the stability and applicability of high-specific-power flexible solar cell modules fabricated using the interconnection strategy and encapsulation structure proposed in this work.