후면 전극 실리콘 태양전지의 emitter 및 LBSF 구조 개선에 관한 연구
A study on the structure improvements of the emitter and LBSF for the back contact silicon solar cell
- 주제(키워드) 후면 전극 실리콘 태양전지 , emitter 및 LBSF 구조 개선
- 발행기관 고려대학교 대학원
- 지도교수 박정호
- 발행년도 2012
- 학위수여년월 2012. 8
- 학위구분 석사
- 학과 일반대학원 전기전자전파공학과
- 세부전공 전자전기컴퓨터공학전공
- 원문페이지 122 p
- 실제URI http://www.dcollection.net/handler/korea/000000035605
- 본문언어 한국어
- 제출원본 000045718774
초록/요약
Conventional energy resources are limited and have environmental problem. The independent development of the new renewable energy source is required due to the environmental problem and the energy depletion. The concern of the solar industry was more enlarged because of Japan Fukushima nuclear power plant explosion accident and instability of oil price. It has advantages that are semi-permanent and non-polluted. So, solar industry is most attractive. According to the substrate type, the solar cell is classified into the single crystal silicon solar cell, polycrystalline silicon solar cell, and amorphous silicon solar cell. Among the silicon solar cell, high efficiency solar cells are IBC SC (Interdigitated Back Contact Solar Cell), PERL (Passivated Emitter Rear Locally diffused) solar cell, and BCSC (Buried Contact Solar Cell). This thesis focused on IBC solar cell. IBC solar cell offers several advantages compared with conventional solar cells. Advantages of IBC solar cell include the elimination of grid shadowing, optimization of surface passivation, improved aesthetics, and simplification of cell interconnection. So many researchers have studied for improving the conversion efficiency of IBC solar cell. Recently, the demand for high efficiency solar cells is increased due to obtaining high efficiency at small area. Chinese corporations are accelerating market share of high-efficiency solar cells by producing the selective emitter solar cell. This thesis presents several simulation results of the IBC solar cell. Selective emitter structure was applied to IBC solar cell by using TCAD of two-dimensional numerical simulation of SILVACO Corporation. Also, it presents several simulation results of the IBC solar cell for optimizing the emitter and LBSF (Local Back Surface Field) regions. The influence of several parameters was simulated including emitter and LBSF peak doping concentration, selective emitter and selective LBSF, line contact width, and substrate thickness. First, the performance of the back contact silicon solar cell according to emitter and LBSF peak doping concentration was investigated. From the simulation results, 23.47% conversion efficiency was obtained when the emitter and LBSF peak doping concentration was 5 × 1019 cm-3 and 5 × 1019 cm-3 respectively. When the back contact silicon solar cell has the emitter peak doping concentration (1 × 1019 cm-3) and the LBSF peak doping concentration (1 × 1020 cm-3), conversion efficiency showed the best result. The result of conversion efficiency was 23.79%. Above emitter peak doping concentration (1 × 1019 cm-3), conversion efficiency was decreased due to the band gap narrowing. It caused high back surface recombination velocity (BSRV). When LBSF peak doping concentration is higher than 1 × 1020 cm-3, convention efficiency was decreased due to high BSRV. Second, the effects of back contact silicon solar cell according to selective emitter (SE) and selective LBSF peak doping concentration were investigated. The SE and LBSF peak doping concentration was varied in 2 × 1020 cm-3 ~ 1 × 1021 cm-3 range when the emitter and LBSF peak doping concentration was 1 × 1019 cm-3 and 5 × 1019 cm-3 respectively. As the SE peak doping concentration increases, open-circuit voltage was decreased due to the rise of saturation current. It leads to the decrease of conversion efficiency. But, conversion efficiency is increased according to the increase of the LBSF peak doping concentration of 2 × 1020 cm-3 ~ 1 × 1021 cm-3 because the saturation current was decreased. Third, the effects of back contact silicon solar cell according to rear structure changes were analyzed. The changes of the rear structure include emitter and LBSF, selective LBSF, SE, and SE &selective LBSF. In other words, simulation was processed according to presence of SE (2 × 1020 cm-3) and selective LBSF (1 × 1021 cm-3) respectively. The conversion efficiency was 23.76% when the LBSF and emitter peak doping concentration was 5 × 1019 cm-3, 1 × 1019 cm-3. The conversion efficiency of back contact silicon solar cell with SE was higher than selective LBSF. The conversion efficiency of back contact silicon solar cell with selective LBSF and SE was 23.92%, 24.45% respectively because of the lower series resistance with SE than selective LBSF. Fourth, the line contact width on emitter and LBSF regions was changed in the 1 µm ~ 5 µm ranges. The conversion efficiency was increased due to the reduction of BSRV and decrease of contact resistance according to reducing the line contact width. The best result of conversion efficiency was 25.42% when the back contact silicon solar cell has the line contact width of 1 µm. Finally the influence of cell thickness (10 µm ~ 200 µm) of back contact silicon solar cell has been analyzed. As the cell thickness increases from 30 µm to 200 µm, the recombination velocity and the series resistance was increased. That leads to reduction of the conversion efficiency. The best result of conversion efficiency was 25.58% when the thickness of the cell is 30 µm. In conclusion, this thesis suggests the optimal structure of the emitter and LBSF on rear side to increase the conversion efficiency. The best efficiency of the back contact silicon solar cell has been obtained with the formation of SE and selective LBSF.
more목차
목차 i
그림 목차 iv
표 목차 vii
Abstract viii
제 1 장 서론 1
1.1 태양광에너지 3
1.2 태양광 발전 특징 5
1.3 태양전지 종류 및 발전현황 6
1.4 결정질 실리콘 태양전지 10
1.5 태양전지 연구동향 14
제 2 장 이론적 배경 18
2.1 태양전지 동작원리 18
2.2 태양전지의 전류-전압특성 21
2.2.1. 단락전류 (short-circuit current, Isc) 24
2.2.2. 개방전압 (open-circuit voltage, Voc) 25
2.2.3. 곡선인자 (fill factor, FF) 26
2.2.4. 변환효율 (conversion efficiency, η) 31
2.3 양자효율 (quantum efficiency, QE) 31
2.4 Dark I-V 곡선 측정 34
2.5 Selective emitter 구조 및 특성 36
2.6 후면 전극 실리콘 태양전지의 구조 및 특성 38
제 3 장 후면 전극 실리콘 태양전지의 공정 시뮬레이션 41
3.1 SILVACO TCAD를 이용한 시뮬레이션 41
3.2 셀 설계 및 구조 제작 43
3.2.1. 셀 설계 및 변수 설정 43
3.2.2. ATHENA를 이용한 태양전지 셀 구조 제작 45
3.3 ATLAS를 이용한 특성 분석 49
3.3.1. Auger recombination 모델 49
3.3.2. Shockley-Read-Hall recombination 모델 49
3.3.3. Band gap narrowing 모델 50
3.3.4. Lombardi CVT 모델 51
3.3.5. 표면 재결합 모델 52
제 4 장 후면 전극 실리콘 태양전지의 성능 분석 54
4.1 Emitter 및 LBSF의 피크 도핑 농도에 따른 태양전지 성능 분석 54
4.1.1. Emitter 피크 도핑 농도에 따른 태양전지 성능 분석 54
4.1.2. LBSF 피크 도핑 농도에 따른 태양전지 성능 분석 60
4.2 Selective emitter 및 selective LBSF의 피크 도핑 농도에 따른 효율 영향 65
4.3 Selective emitter 및 selective LBSF의 유무에 따른 태양전지 성능분석 68
4.4 Emitter 및 LBSF의 선 접촉 너비에 따른 태양전지 성능 분석 71
4.5 기판 두께에 따른 태양전지 성능 분석 74
제 5 장 결론 및 고찰 77
참고문헌 80
Appendix 84
Appendix 1: Emitter 및 LBSF 피크 도핑 농도 변화에 따른 태양전지 성능 분석 simulation (emitter: 5 × 1019 cm-3, LBSF: 5 × 1019 cm-3) 84
Appendix 2: Selective emitter 및 selective LBSF 피크 도핑 농도 변화에 따른 태양전지 성능 분석 simulation (SE: 2 × 1020 cm-3, selective LBSF: 2 × 1020 cm-3) 91
Appendix 3: Selective emitter 및 selective LBSF 유무에 따른 태양전지 성능 분석 simulation (SE: 2 × 1020 cm-3 를 형성시) 95
Appendix 4: Emitter 및 LBSF 의 선 접촉 너비에 따른 태양전지 성능 분석 simulation (Line contact width: 1 µm) 98
Appendix 5: 기판 두께에 따른 태양전지 성능 분석 simulation (substrate thickness: 10 µm) 101
