The development of GaAs multijunction solar cell began in the 1950s and has a history of more than 50 years. In 1954, it was found that GaAs has photovoltaic effect. In 1956, loferski J. J. and his team explored the physical properties of good materials for manufacturing solar cells.
They pointed out that the gallium arsenide materials with eg in the range of 1.2-1.6 EV have high conversion efficiency，In the 1960s, gobat et al. Developed the first Zn doped GaAs solar cell, but the conversion rate was only 9% ～ 10%, far lower than the theoretical value of 27%，In the 1970s, IBM and Ioffe Institute of technology and physics of the former Soviet Union adopted LPE (liquid phase epitaxy) technology to introduce GaAlAs heterogeneous window layer, which reduced the recombination rate of GaAs surface and made the efficiency of GaAs solar cells reach 16%. Since the 1980s, GaAs solar cell technology has experienced several development stages from LPE to MOCVD, from Homoepitaxy to heteroepitaxy, and from single junction GaAs solar cell to multi junction GaAs solar cell stacked structure. Its development speed is accelerating, and its efficiency is also improving. At present, the laboratory efficiency has reached 50% (from IBM data), and the industrial production conversion rate can reach more than 30%
At 240 solar (24.0w/cm2, am1.5d, low aerosol optical depth, 25 ℃). This is a preliminary demonstration of more than 40% solar cell efficiency, and is the highest solar conversion efficiency of any type of photovoltaic equipment so far. This show GaAs multijunction solar cell with ingap 40% efficiency. The lattice matched concentrating cell has reached 40.1% efficiency. The electron hole recombination mechanism in modified GaxIn1 XAS and GaxIn1 XP materials is analyzed, and the basic power loss is quantified to determine the way to achieve higher efficiency.
The results show that the measured efficiency of one sun is higher than the Shockley queisser limit efficiency of 30% at 1 sun, and the concentrator cell is higher than the theoretical limit of 37% at 1000 sun. The experimental multi junction cell architecture using modified materials, four or more junctions and other design methods may improve the efficiency of the actual ground concentrator cell by more than 45%, or even 50%.
Band gap Eg (eV) @300 K:1.42
Affinity (eV):4.07
Heavy e− effective mass (me*/m0):0.063
Lifetime (el) (s):1.00e−09
ni (per cc):2.12e+06
Vsatn (cm/s):7.70e+06
Vsatp (cm/s):7.70e+06
Band gap Eg (eV) @300 K:1.9
Affinity (eV):4.16
Heavy e− effective mass (me*/m0):3
Lifetime (el) (s):1.00e−09
ni (per cc):7.43e+04
Vsatn (cm/s):1.00e+06
Vsatp (cm/s):1.00e+06
Band gap Eg (eV) @300 K:2.3
Affinity (eV):4.2
Heavy e− effective mass (me*/m0):2.85
Lifetime (el) (s):1.00e−09
ni (per cc):1
Vsatn (cm/s):1.00e+06
Vsatp (cm/s):1.00e+06