QUESTION 4 [30 Marks] (a) Determine the probability that an energy level which is 0.3 eV below Fermi energy is 1% unoccupied by an electron at 300K? The Fermi energy is 6.25 ev. (4 marks) (b) A Silicon solar cell of size 2 cm x 2 cm with In = 32 nd has an optical generation rate of 10EHP/em-see within L, L=2 um of the junction. If the depletion width is 1, calculate the Is and Voc for this cell (4 marks) (c) What are the recombination processes (discuss at least two processes) involved in the following solar cells: amorphous Si-solar cell i) dye-sensitized solar cell (use a schematic energy level diagram) (6 marks) (d) What is the origin for the blue shift in quantum dots? (4 marks) (e) Consider the figure below. Justify why LiFePO4 vs LifTis012 cell will have (1) lower energy and (ii) higher rate of charging than the LiFePO4 vs graphite cell. Voltage (V vs. ULT) 3.6 LiFePO, 170mAIVE 14.7.0.3: 170 mAh/ Graphite: 370 mAh/8 24 TO graphite 80 100 20 40 BO of actual capacity LiFePO, Lit + e + FePO4 Li_Tis012 + 3Li+ + 3e Li-Tis012 Lit + e +6C LICE (4 marks) (1) Consider insertion reaction and alloy reaction for lithium storage. Explain why) alloy reaction has higher capacity and (ii) larger volume expansion than the insertion reaction for lithium storage (4 marks) Pg 9 MESS16 (g) Consider the fuel cells at 25C and SOC. Explain the reason why the open circuit voltage of the fuel cell at 25C is 1.26 times higher than the cell at 800