The solar cell is a semiconductor electronic device that can effectively dilute solar radiation and convert it into electrical energy. The following is a description of the research on solar cells by the Beijing Solar Photovoltaic Research Center The research and development of crystalline silicon high-efficiency solar cells and polycrystalline silicon thin film solar cells and the transformation of research results to industrialization.
1. Research and development projects of high-efficiency crystalline silicon solar cells in the photoelectric center of high-efficiency crystalline silicon solar cells include passive emission area solar cells (PESC), buried grid solar cells (BCSC) and polycrystalline silicon solar cells. ● The basic purpose of the Passive Emitting Zone Solar Cell (PESC) Photoelectric Center to research passive emitting zone solar cells (PESC) is to explore various mechanisms that affect the efficiency of cells, provide theoretical and technological basis for reducing the cost of solar cells, and promote the development of solar cell theory.
The materials used in the experiment are zone melting (FZ), p-type (boron doped) [100] monocrystalline silicon with resistivity ρ＝ 0.2 ～ 1.2 Ω cm, thickness t ＝ 280 － 350 μ m. Polished on both sides. The battery process includes front inverted pyramid texturing, front and rear surface passivation, preparation of selective emission zone, antireflection surface, back field, front and rear metal contact, etc. The current battery level is shown in Table 1. Table 1 Performance of PESC battery (test condition AM1.5, 25 ℃) Voc (mV) Jsc (mA/cm2) FF η () A (cm2) Test unit 656.137.40.80619.794.04 Beijing Solar Energy Research Institute * VOC open circuit voltage, JSC short circuit current density, FF filling factor, η Conversion efficiency, A solar cell area (the same below) ● The manufacturing process of buried grid solar cells (BCSC) eliminates complex multiple photolithography and evaporation electrode steps, reduces the number of high-temperature oxidation, and greatly simplifies the entire battery manufacturing process; Buried grid not only reduces the shadow area of the electrode, but also reduces the ohmic contact resistance. It is a highly efficient battery technology that can be industrialized. The materials used in the experiment are: ① FZ, p-type (boron doped) [100] monocrystalline silicon, thickness t=300-400 μ m； ② Czochralski (CZ), p-type (boron doped) [100] monocrystalline silicon, thickness t=300-400 μ m； ③ Solar grade (double drawing), p-type p [100] monocrystalline silicon, thickness t=300-400 μ m。
The process of battery includes surface texturing, passivation, preparation of selective emission region, antireflection surface, back surface field and metallization. The current battery level is shown in Table 2. Table 2 Performance of BCSC batteries made of different materials (test conditions: AM1.5, 25 ℃) Material (groove) Voc (mV) Jsc (mA/cm2) FF () η ()A(cm2) ρ (Ω. cm) Test unit FZ (laser) 663.835.680.5818.6250.2AFZ (mechanical) 621.937.080.0218.4740.5 BCZ (laser) 622.935.279.2717.22250.8B Solar level, In order to meet the needs of the future development of polysilicon solar cells in China. The material used in the experiment is Bayer’s p-type polysilicon chip with a thickness of 340 μ m. The process of cell fabrication includes gettering, p-n junction preparation, passivation, back field formation and metallization. The characteristics of the best battery prepared in the experiment are shown in Table 3. Table 3 Performance of PESC battery (test condition: AM1.5, 25 ℃) Voc (mV) Jsc (mA/cm2) FF η () A (cm2) Test unit 595.034.230.712914.531.0 Beijing Solar Energy Research Institute 581.029.920.678711.810 × 10 (Cooperative project with Beijing Nonferrous Metals Research Institute) 2. Polycrystalline silicon thin film solar cells Polycrystalline silicon thin film solar cells have the advantages of stable performance, mature technology and high efficiency of bulk material crystalline silicon cells, and have the potential to significantly reduce the amount of materials used, thereby significantly reducing the cost, so they have become a research hotspot in the photovoltaic industry. The photoelectric center adopts rapid thermal chemical vapor deposition (RTCVD), plasma enhanced chemical vapor deposition (PECVD) and a-Si/ μ The polycrystalline silicon thin film solar cells were studied by different processes such as c-Si laminated cells. RTCVD polycrystalline silicon film SiH2Cl2 or SiCl4 is deposited in the quartz tube reaction chamber with raw gas. At the beginning of the research, the battery performance was listed in Table 4 with heavily doped inactive silicon as the substrate. Figure 1 Structure of RTCVD polycrystalline silicon thin film solar cell The structure of PECVD polycrystalline silicon thin film solar cell is: (Al/Ag)/ITO/p-a-Si: H/n-a-Si: H/n-poly-Si/n++inactive Si substrate (0.005 Ω cm)/Ti Pd Ag. In which, n-type Poly Si film (～ 10 μ m) It was prepared by rapid PECVD and solid phase crystallization. The battery performance is listed in Table 4. a-Si／ μ The structure of c-Si laminated battery (cooperated with Institute of Semiconductors, Chinese Academy of Sciences) is: glass/SnO2 film/p-i-na-Si: H-cell stewed p-i-n μ C-Si: H battery stewed with Al. The battery performance is listed in Table 4. Table 4 Performance of polycrystalline silicon thin film solar cells (test conditions: AM1.5, 25 ℃) Voc (mV) Jsc (mA/cm2) FF η () A (cm2) battery process 625.6426.30.735712.111.0RTCVD455.021.180.64746.151.0PECVD116011.40.6740.8.10.126RECVD (a-Si/pc si) 3. The solar cell performance test center has established a solar cell and material test laboratory and purchased necessary equipment. These equipment include I-V test system, spectral response test system, C-V test system, atomic force microscope, and film thickness test system, ensuring the need for research and development.
