Thin and Flexible Triple Junction Cells 30% Efficient: Qualification Results and Future Space Applications

Effect of the Irradiation on Optical and Electrical Properties of Triple-Junction Flexible Thin Solar Cells for Space Applications

“…A batch of 50 cells has been selected at random for the qualification campaign at bare solar cell level. The selected conditions allow to obtain thin substrates with good thickness uniformity, without significant degradation of the electrical performances with respect to the standard 140 µmthick (CESI CTJ30) solar cells [20,23]: despite their smaller thickness, a 29% efficiency AM0, 25 • C has been demonstrated on these devices, together with a bending radius of 30 mm [19] (see Figure 1B). As the etch-based thinning process is carried out on the substrate only, the decrease of the device thickness is obtained without influencing the subcell layers.…”

“…The studied samples are CTJ30-80 solar devices manufactured by CESI: they are InGaP/InGaAs/Ge triple junction solar cells with a size of 26.5 cm 2 and AM0 efficiency class 30%, which have been manufactured and qualified in accordance with the standard ESA ECSS E ST20-08C Rev. 1 [19]. Such devices are based on the CTJ30 CESI technology, a class of solar cells with standard thickness of 140 µm which are used on several satellites since 2013 [21].…”

“…In addition to these, a further request recently has arisen of increasing versatility and adaptability to the spacecrafts by having bendable and mechanically flexible solar arrays [13][14][15][16][17]. These issues suggest that new designs of multi-junction high-efficiency solar cells must be devised: a fruitful approach is based on manufacturing multi-junction III-V solar cells with thin substrates (typically <100 µm), which should allow both lightness (high specific power) and structural flexibility [18,19]. Such technologies have the potential to strongly decrease the mass of the photovoltaic device, with beneficial effects also on the cost of the solar cells.…”

Measurement of the limiting subcell in multijunction space solar devices by restricted‐wavelength‐range illumination

“…As expected by the literature, the tested cells are more sensitive to the irradiation dose than to the particle energy 6,10,16 : Congruently, we observe that the arising of a middle-limited regime in EOL2 sample is fundamentally due to the employed high dose, which is more intense with respect to the case of EOL1 sample, rather than the kind and energy of the involved particles, as pointed out in previous studies. 32,33 It is also worth noting that this RWRI technique is able to provide a strong remark of the occurrence of a current limitation driven by the middle subcell (middle-limited cell condition): Actually, a strong qualitative difference is displayed between the behavior of the curves in top-limited configuration (BOL and EOL1, Figures 4 and 5, respectively) and in middle-limited configuration (EOL2, Figure 6).…”

“…As expected by the literature, the tested cells are more sensitive to the irradiation dose than to the particle energy(): Congruently, we observe that the arising of a middle‐limited regime in EOL2 sample is fundamentally due to the employed high dose, which is more intense with respect to the case of EOL1 sample, rather than the kind and energy of the involved particles, as pointed out in previous studies. ()…”