Evaluation of Perovskite Hole Selective Contacts for Silicon Solar Cells
YanSyun Chen1, Li-Yu Li Li2, Peichen Yu3, Yu-Chiang Chao4, HsinFei Meng5, Sheng-fu Horng6
1Institute of Electronics Engineering, National Tsing-Hua University, Hsinchu, Taiwan
/2Industrial Technology Research Institute(Green Energy and Environment Research Laboratories), Hsinchu, Taiwan
/3Department of Photonics, National Chiao-Tung University, Hsinchu, Taiwan
/4Department of Physics, National Taiwan Normal University, Taipai, Taiwan
/5Institute of Physics, National Chiao-Tung University, Hsinchu, Taiwan
/6Institute of Electronics Engineering, National Tsing-Hua University, Hsinchu, Taiwan

With the mature development of silicon-based solar cells, it is clear that the high-efficiency device requires superior surface passivation and carrier-selective contacts (CSCs). However, the conventional CSCs mostly employ heavy doping to differentiate the conductivity of the majority carriers from that of the minority carriers. In recent years, dopant-free carrier-selective materials have garnered significant interest to replace the complex diffusion process.
In this work, we investigate the potential and stability of perovskite(MaPbI3) as the hole-selective contact materials because perovskite has excellent carrier transport properties for both electrons and holes. A conventional n+/p silicon solar cell structure is employed, where the front (n+) side has random pyramidal surface textures and the rear (p) side is a polished planar surface(This structure is used to make device that  made by ITRI). First, we have overcome the problem of forming a continuous perovskite thin film on silicon due to low surface energy. The cleaned silicon wafers are placed in an ambient of 22 ° C ± 2 ° C and 55% ± 5% humidity for six hours to grow a thin layer of native oxide. The MAPBI3 solution is then spin-coated onto the polished plane using a one-step process. While spinning, differentiating solvent  of toluene/CB  is added after 2-7 seconds to cause MAPBI3 to crystallize on the silicon surface, forming a continuous thin film. Finally, 100nm-thick silver electrodes are evaporated on both sides to finish the device fabrication. We find that short-circuit current density (Jsc) increases by 0.6mA/cm2 from 27.73 to 28.32 mA/cm2 and the open-circuit voltage (Voc) increases by 5mV from 517.36 to 512.50 mV, reaching a power conversion efficiency of 10.53%. The solar cell with the perovskite(MaPbI3) hole selective layer exhibits better performance than the reference counter part. According to the external quantum efficiency (EQE) characterization, their spectra are almost overlapping. The work is still in process. we will further engineer the composition of the PbBr2 and PbI2 to modify the work function and enlarge the hole selectivity.