臺灣博碩士論文加值系統

對於聚光型太陽能電池而言，加速衰退試驗(Accelerated Degradation Test；ADT)是一項重要的試驗方法。ADT有兩種方法：固定應力(Constant Stress)加速衰退試驗(CSADT)和逐步應力(Step Stress)加速衰退試驗(SSADT)。
本實驗主要是針對未塗佈光學膠的III-V族化合物聚光型InGaP/InGaAs/Ge太陽能電池進行逐步應力加速衰退試驗(SSADT)，探討其衰退機制及成因。實驗溫度分別為90、110、130和150℃，累積時數為25、55、85和135小時。
經過本實驗，可得知GaInP/GaInAs/Ge太陽能電池經過SSADT後，暗電流-電壓曲線的變化明顯看出邊緣復合電流的增加，另一方面藉由光電流-電壓曲線得知開路電壓與填充因子呈現逐步下降的現象。以上趨勢與電池的效率變化皆呈現正相關的特性。

Accelerated degradation test (ADT) is an essential tool to demonstrate reliability of concentration solar cells. There are two methods of accelerated degradation test：constant stress accelerated degradation test (CSADT) and step stress accelerated degradation test (SSADT).
The purpose of this study is to examine the degradation mechanism of GaInP/GaInAs/Ge solar cells.
We analyzed the degradation mechanism of GaInP/GaInAs/Ge triple junction solar cells without coating any protective film. Gradual degradation in the dark and light I-V characteristics of the solar cells were observed after the step stress accelerated degradation tests (SSADT) were conducted on these devices sequentially at 90, 110, 130 and 150℃for 25, 55, 85 and 135 hours, respectively. The recombination current in the depletion region at the chip perimeter of solar cells, resulting in the decrease of open-circuit voltage (VOC), fill factor (FF) and efficiency, is suggested to be the important degradation mechanism for GaInP/GaInAs/Ge triple junction solar cells.

Content
摘要……………………………………………………...……………….I
English abstract…………………………………………..……………...III
致謝……………………………………………………………………...V
Content…………………………………………………………………VII
Figure captions………………………………………………………….IX
List of table……………………………………………………………....X
Chapter 1 Introduction
1.1 Why we need solar energy?................................................................1
1.2 Photovoltaic systems..........................................................................1
1.3 Concentrating PV................................................................................1
1.4 Multiple junction cells........................................................................2
1.5 Unique design of GaInP/GaInAs/Ge triple junction solar cells…….3
Chapter 2 Theory foundation of the solar cell
2.1 Solar irradiance spectrum…………………………………….……..5
2.2 How a solar cell works…………………………………….………..5
2.3 Fundamental parameters of solar cells…………………………...…6
Chapter 3 The measurement systems
Current-voltage (I-V) of solar cells measurement………………………9
Chapter 4 The experiments
4.1 Introduction………………………………………………………….9
4.2 Experiment
4.2.1 Definition of failure…………………………………………...10
4.2.2 Experimental description ………………………………….….11
Chapter 5 Result and discussion………………………………………...13
Chapter 6 Conclusions…………………………………………………..17
References………………………………………………………………31
Figure Captions
Figure 1.1 A model of GaInP/GaInAs/Ge triple junction solar cell.………………………………………………………………….…..18
Figure 1.2 Better utilization of the solar spectrum through the multijunction approach.…………………..……………………………..18
Figure 2.1 Solar irradiance spectrum above atmosphere and at surface when the air-mass value is AM 0…...…………………….……………..19
Figure 2.2 Schematic illustration of AM 0, AM 1, AM 1.5 and AM2……………………………………………………………………..19
Figure 2.3 A photovoltaic cell under illumination generates electricity as electrons moves to the conduction band leaving holes behind in the material...………………………………………………………………..20
Figure 2.4 Loss processes in a standard solar cell：(1) non-absorption of below bandgap photons；(2) lattice thermalization loss；(3) and (4) junction and contact voltage losses；(5) recombination loss……..………………………………………………………………..20
Figure 2.5 Single solar cell model…………………….......…...………..21
Figure 2.6 The I-V characteristic of solar cells..………...…….………..21
Figure 3.1 Photo of the current-voltage characteristic measurement system：solar simulator……………………………………….………..22
Figure 3.2 Schematic illustration of Fresnel lens………...……………..23
Figure 4.1 Photo of experimental cell…………………………………..23
Figure 4.2 Time sequence of SSADT performed in test A and B…..…..24
Figure 5.1 schematic illustration of GaInP/GaInAs/Ge triple junction solar cell……………………………………………………………..…..24
Figure 5.2(a) Typical dark I-V curves of the cells that passed test A (b) Typical light I-V curves of the cells that passed test A.……………………………………………...…………………...……25
Figure 5.3(a) Dark I-V curves measured sequentially after each treatment for the same cell failed the test A at the 90℃-treatment step. (b) Light I-V curves measured sequentially after each treatment for the same cell failed the test A at the 90℃-treatment step. …………………...…………...….26
Figure 5.4(a) Typical dark I-V curves of the cells that passed test B. (b) Typical Light I-V curves of the cells that passed test B. …………………………….……………………………………..…..27

List of Tables
Table 5.1 Number of failed cells found in each step of test A.…………………………………...……………………………….…..28
Table 5.2 Series resistance in each step of test A. ……………………...28
Table 5.3 Effects of Test A on VOC, FF and efficiency.…………………………………………...…………………...29
Table 5.4 Effects of Test B on VOC, FF and efficiency.……………………………………………...…………….…..30

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