用电学参数表征晶体硅太阳电池特性

Characterization of crystalline silicon solar cells by electrical parameters

为了分析3种不同类型的商业太阳电池片,即P型铸造多晶硅太阳电池、定边喂膜生长硅(EFG)太阳电池和单晶硅太阳电池中存在的影响电池效率的可能性缺陷,对太阳电池的电性能参数如光谱响应曲线、短路电流的二维分布、串联电阻、并联电阻、二极管理想因子、反向饱和电流等进行了表征和分析。对比分析了对太阳电池增加偏置白光前后的光谱响应(外量子效率EQE)曲线,然后采用光束诱导电流(LBIC)法和电流-电压(I-V)(暗,光照)法分别测试了太阳电池中形成漏电缺陷的面分布和太阳电池的电性能参数并借助于太阳电池的二极管等效模型拟合了I-V曲线。结合这3种分析测试方法,得出在铸造多晶硅、EGF太阳电池中影响电池参数的主要缺陷是晶界、位错以及材料中的杂质,而影响单晶硅太阳电池的却是存在于体内的金属杂质等。由于原材料中存在不同的少子复合中心,使最终多晶硅,EFG和单晶硅太阳电池的转换效率分别为10.5%,11.7%和15.7%。

In order to analyze the possible defects effecting on efficiency of three types of industrial silicon solar cells： P-type of cast-multicrystalline silicon, Edge-defined Film-fed Growth （EFG） and single silicon solar cells, several important cell parameters, such as the curve of spectral response （External Quantum Efficiency, EQE）, mapping of short-circuit current, ideality factors of diodes, saturation currents I0 and the parasitic resistances Rs and RSH, were characterized and analyzed. After analyzing EQE curve with and without bias white light during EQE measurement, the mapping of defect induced shunt current in solar cells and electrical parameters of solar cells were respectively measured by Light Beam Induced Current （LBIC） and dark and illuminated current-voltage （I-V） measurements. Then, based on diode equivalent model of solar cell, the simulation of measured I-V curve was used to obtain some important parameters of solar cells. From these results, it shows that the main defects effecting on salar cell parameters are the grain boundaries, dislocation and impurity in bulk silicon for cast-multicrysalline silicon and EFG solar cells, but born-oxygen defect pairs for single silicon solar cell. Because of the variable type of minor carrier recombination centers in raw material, the final conversion efficiencies of cast-multicrystalline silicon, EFG and single silicon solar cells are 10. 5%, 11.7% and 15.7%, respectively.