Solar cells diode quality factor

For solar cells, the fill factor FF determines the position of the maximum power point in the 4th I/V quadrant of the illuminated diode and is therefore a quality sign of the photodiode. Besides the increased efficiency, the FF of a photodiode is also important when evaluating the proper function of the diode. High FF values are expected only for diodes with a strict selection principle for the separation of positive and negative carriers. There are several loss mechanisms for photodiodes that can reduce the FF in a photodiode ... 

Performance and Diode Parameters. For finding the optimum absorber composition, organic solar cells of the type A with various [CuPc] [C60] ratios were prepared at a non-optimised substrate temperature. The Eff behaviour with the absorber composition (Fig. la) is dominated by the behaviour of the Jso and FF [4], In the compositional range investigated, 0.2 < [CuPc]/([CuPc] + [C60]) < 0.8, the devices V00 is almost constant taking values of about 400 mV (not shown). An efficiency of 1.6% is achieved in Fig. la at a [CuPc] [C60] composition of about 1 1 (by weight) [4], The diode quality factor, n. of the devices decreases from 2.6-2.7 at the either minimum of CuPc or C6o content to 1.8 at 1 1 absorber composition. At the same time, the OSCs series resistance decreases almost symmetrically from 0.34-0.38 Q x cm2 at a content of 17% of either CuPc or C to -0.2 Q x cm2 at an identical content of CuPc and C6o-... 

In 1983 the application of doped tin oxide films to silicon solar cells has been reported [5]. lida and coworkers realized a setup with the following characteristics 7sc = 14 mAcm", Kic = 800 mV, efficiency = 7.5 % and fill factor = 0.67. Vishwakarma et al. [166, 167] prepared arsenic-doped tin oxide films for silicon solar cells and investigated the diode properties of Sn02 As/Si02/n-Si and Sn02 As/n-Si cells. The barrier height 0 was 0.78-0.89 eV and 0.68-0.69 eV, respectively, and the reverse saturation current density 7u was 2-45 pAcm and 0.07-9.2 pAcm", respectively, with diode quality factors of 2.2-2.9 and 1.7-1.9. The optimized results for solar cell applications are given below... 

A simple replacement circuit based on one-diode model of a solar cell, shown in the inset of Figure 10.21, consists of a diode (represented by its quality factor n, and the reverse bias, dark saturation current jo), and a series resistor and a parallel resistor Rp that account for ohmic losses and shunt leakage through the diode, respectively. The photocurrent generation is represented by a current source jpi,. 

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