在电子传输层中添加PVK提高钙钛矿太阳能电池的性能

为了探究PVK对倒置平面异质结钙钛矿太阳能电池电子传输层的影响,向电子传输层PCBM中添加了一种富电子的聚乙烯基咔唑(PVK).采用原子力显微镜、PL光谱对薄膜进行了表征.实验结果表明:少量PVK的添加提高了覆盖在钙钛矿薄膜上PCBM层的平整度.当PVK的添加质量分数为4%时得到最佳器件效率,相比于纯PCBM作为电子传输层的器件,器件效率由(5.11±0.14)% 提升到(9.08±0.46)%.当PVK的添加质量分数大于4%时,粗糙度又趋于变大.PL光谱显示,少量PVK的加入使钙钛矿/电子传输层薄膜的PL强度降低,并使PL峰蓝移.研究表明:向PCBM中掺杂适量PVK能够改善钙钛矿/电子传输层/Al的界面接触,减少漏电流,并能够减少钙钛矿表面陷阱和晶界缺陷,减少电荷复合,从而提高了器件性能.

Improving The Performance of Inverted Planar Heterojunction Perovskite Solar Cells via Poly(n-vinylcarbazole) as Additive in Electron Transporting Layer

An electron-rich poly(n-vinylcarbazole) (PVK) was applied to dope the [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) to explore the influence of PVK on the electron transfer layer of planar heterojunction perovskite solar cells.Under the optimized PVK doping mass fraction of 4%, the power conversion efficiency (PCE) of the CH3NH3PbI3 perovskite solar cells is enhanced from (5.11±0.14)% to (9.08±0.46)%.According to the surface morphology study of the electron transport layer, PVK doping improves the coverage and quality of PCBM layer onto the rough perovskite layer, and this is beneficial for the interfacial contact of the CH3NH3PbI3, PCBM films and the top Al electrode, which results in the decrease of leakage current.Moreover steady-state PL analysis shows that the electron-rich PVK have a better passivation effect on the trap states at the perovskite surface or crystal boundaries as a material of interfacial modification of cathodes, thus can apparently decrease the charge recombination of the perovskite solar cells.