利用有机体相异质结增强CsPbBr3钙钛矿太阳能电池的电荷提取以及光谱吸收

Tailoring organic bulk-heterojunction for charge extraction and spectral absorption in CsPbBr perovskite solar cells

全无机CsPbBr_(3)钙钛矿太阳能电池能够很好地平衡传统杂化器件的效率和稳定性问题.然而,较大的电荷传输势垒以及较窄的吸光范围已经成为限制器件效率进一步提升的两大挑战.本文通过构建有机体相异质结(P3HT:PCBM光活性层)加速器件电荷提取并扩宽吸光范围,通过进一步优化P3HT:PCBM光活性层的厚度,获得了8.94%的光电转换效率,远高于单一CsPbBr_(3)作为吸光层的电池效率(6.28%).通过系统的测试表征发现PCBM中的羰基与钙钛矿表面未饱和的铅原子相互作用能够有效地钝化缺陷态,减小器件的复合反应.另外,PCBM和P3HT之间的相互耦合将器件的吸光范围扩宽至650 nm,能够在不降低电池开路电压的前提下增加光生载流子的数量,提高电池器件的短路电流.尤为重要的是,器件在70%相对湿度下存放75天仍能保持相对稳定.高效、稳定、可大规模制备的优势能够加速无机钙钛矿太阳能电池的商业化进程.

All-inorganic CsPbBr_(3)perovskite solar cells(PSCs)are promising candidates to balance the stability and efficiency issues of organic-inorganic hybrid devices.However,the large energy barrier for charge transfer and narrow spectral response are still two challenging problems for performance improvement.We present here an organic bulkheterojunction{poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C61 butyric acid methyl ester(P3HT:PCBM)}photoactive layer to boost the charge extraction and to widen the spectral absorption,achieving an enhanced power conversion efficiency up to 8.94%by optimizing the thickness of P3HT:PCBM photoactive layer,which is much higher than 6.28%for the pristine CsPbBr_(3)device.The interaction between the carbonyl group in PCBM and unsaturated Pb atom in the perovskite surface can effectively passivate the defects and reduce charge recombination.Furthermore,the coupling effect between PCBM and P3HT widens the spectral response from 540 to 650 nm for an increased short-circuit current density.More importantly,the devices are relatively stable over 75 days upon persistent attack by 70%relative humidity in air condition.These advantages of high efficiency,excellent long-term stability,cost-effectiveness and scalability may promote the commercialization of inorganic PSCs.