Papers by Keyword: GaInP

Abstract: This paper presents a numerical simulation of a dual-junction tandem GaInp/GaAs cell made from top GaInp and bottom GaAs cells. For this purpose, we utilized a numerical simulation tool. Two methodologies were proposed, the first method consists of simulating each base layer cell of the top and bottom separately, and the second method simulated both layers in one file, to simulate both in one file. For improved electric characteristics of tandem solar cells, the current-match requirement between the top and bottom cells should be satisfied, necessitating the careful design of parameters. The top base GaInp layer thickness is adjusted to match this requirement. The solar spectrum reaching the lower cell is analytically calculated by subtracting the top cell spectrum from the total spectrum. the optimal value of short current density corresponds with a top cell base thickness of 0.8 µm, this results in an open circuit voltage of 2.45 V, a short circuit current of 15.7 Am/cm², a fill factor of 91 %, an efficiency of 35 % for the first method and the second method used a script file designed to verify the above results and confirmed the values to be; 2.68 V open circuit voltage, 15.26 Am/cm², a short circuit current, 90 % fill factor, and 36.86 % efficiency under AM 1.5 G solar spectrum.

Abstract: Solar power is seen by many as a solution to the world’s energy problems. The earth receives 1.7x1017W from the sun compared to a total electricity generation capacity of 4.6x1012W (OECD prediction for 2010). However the average power density is low with a daytime average over the earth of 680Wm-2. This makes centralised generation problematic but distributed photoelectric generation by domestic and commercial users is a rapidly developing market. However typical commercially available modules have an energy conversion efficiency of less than 12%. Silicon cells with 24% efficiency have been produced in the lab while multi-junction tandem cells using different semiconductor materials (GaInAs, GaInP and Ge) to absorb different parts of the sun’s spectrum have reached 40%. This chapter describes some of the materials and device achievements so far and looks at possible ways in which higher efficiencies might be achieved with particular emphasis on nano-materials to use more of the solar spectrum efficiently. The possibility of using quantum slicing and multiple exciton generation to make more efficient use of high energy photons is considered and impurity band generation as a possible route to use low energy photons. One of the greatest challenges is to do this cheaply using semiconductors made from non-toxic abundant elements.