基于前驱体Pb(OH)I溶液法制备FAPbI3太阳能电池(英文)

甲脒铅碘因具有高热稳定性和较窄的禁带宽度而受到广泛关注。本工作使用羟基碘化铅代替传统碘化铅、氯化铅,通过一步溶液法制备介孔甲脒铅碘钙钛矿太阳能电池,研究退火温度对材料的结晶性、覆盖层形貌和器件的效率等方面的影响。较之传统的溶液法工艺,基于羟基碘化铅制备的甲脒铅碘薄膜表现出更为优异的热稳定性能。最终在AM1.5G一个太阳光照明下,得到了5.8%的光电转化效率,其中短路电流为18.6mA·cm-2,开路电压为0.67V,填充因子为0.47。

Influence of Photon Pump Fluence on Charge Carriers in FAPbI3 and Manganite Perovskites

FAPbI3 and FA(Mn:Pb)I3 perovskite films were prepared and evaluated through steady and transient absorption spectroscopy. According to the analysis using Elliot’s model, there were no considerable differences except for the absorption intensity between FAPbI3 and FA(Mn:Pb)I3 perovskite films: the value of the optical gap (Eg) and the position of exciton resonance (E0) were the same. The femtosecond transient absorption showed biexponential relaxation properties of the charge carriers, suggesting that biexcitons are more easily generated in FA(Mn:Pb)I3 than FAPbI3 perovskite. The generation of biexcitons in FA(Mn:Pb)I3 was also confirmed by the photon pump fluence dependence. Moreover, we were able to estimate the average number of absorbed photons directly from the photon pump power dependence without needing any further experimental measurements such as photoluminescence. Our findings may offer a new way of understanding photoinduced carrier dynamics in perovskite manganites.

Spontaneous low-temperature crystallization of α-FAPbI3 for highly efficient perovskite solar cells

Formamidinium lead triiodide(HC(NH2)2PbI3 or FAPbI3)is a promising light absorber for high-efficiency perovskite solar cells because of its superior light absorption range and thermal stability to CH3NH3PbI3(MAPbI3).Unfortunately,it is difficult to fabricate high-quality FAPbI3 thin films to surpass the MAPbI3-based cells due to easily forming unwanted but more stable yellow d-phase and thus requiring high annealing-temperature for wanted photovoltaic-active black a-phase.Herein,we reported a novel low-temperature fabrication of highly crystallized a-FAPbI3 film exhibiting uniaxial-oriented nature with large grain sizes up to 2 lm.First-principles energetic calculations predicted that this novel deposition should be ascribed to the formation of a high-energy metastable two-dimensional(2D)intermediate of MAFAPbI3 Cl followed by a spontaneous conversion to a-FAPbI3.The ions exchange reaction during this MAFAPbI3 Cl-FAPbI3 conversion account for the perovskite film uniaxial-oriented grown along the(111)direction.This large-grain and uniaxial-oriented grown a-FAPbI3 based solar cells exhibited an efficiency up to 20.4%accompanying with low density-voltage(J-V)hysteresis and high stability.

单分子液晶添加剂在甲脒铅碘钙钛矿太阳能电池中的应用

溶液制备的钙钛矿薄膜通常含有大量晶界,会降低薄膜结晶质量,导致缺陷复合,不利于提升器件性能。因此,制备更高结晶质量的薄膜来进一步提升能量转化效率是钙钛矿太阳能电池面临的挑战。液晶分子具有强的自组装能力和形貌调节能力,本研究引入一种向列型单分子液晶4-氰基-4′-戊基联苯(5CB)作为甲脒铅碘(CH(NH2)2PbI3,FAPbI3)钙钛矿前驱液的添加剂,可以增大钙钛矿晶粒尺寸,减少晶界。此外,5CB的氰基能钝化钙钛矿晶粒表面未配位的Pb^(2+),降低缺陷态密度,从而抑制非辐射复合。经过优化,添加0.2 mg/mL 5CB的钙钛矿太阳能电池的能量转化效率达到21.27%,开路电压为1.086 V,电流密度为24.17 mA/cm^(2),填充因子为80.96%。本研究证明使用单分子液晶作为添加剂是提升FAPbI3钙钛矿电池性能的有效策略。

Cs掺杂的高性能(NH_2CH=NH_2)_(1-x)Cs_xPbI_3光电探测器

FAPbI_3有机无机杂化钙钛矿光电探测器还存在一些问题,合成纯α相光敏钙钛矿需要较高的退火温度(150~160℃),不利于柔性器件的制备;另外,在常温下,FAPbI_3容易发生α→δ的相变,器件的空气稳定性很差。本文制备了Cs掺杂的二极管型FA_(1-x)Cs_xPbI_3光电探测器。结果表明,Cs的掺杂一方面有效降低了合成纯α相FA钙钛矿的退火温度,另一方面提高了器件性能以及空气稳定性。对比不同Cs掺杂浓度的器件性能,发现掺杂摩尔分数为10%时,器件性能最优,其开关比可达1.6×10~5,响应速度达到7.1μs,在350~800nm宽光谱范围内探测率都在10^(12)cm·Hz^(1/2)·W^(-1)(Jones)量级。本研究为实现低温制备高性能高稳定性的FA钙钛矿光电探测器提供了一条可行的途径。

退火温度对混合阳离子钙钛矿太阳能电池性能的影响

通过不断降低钙钛矿的带隙,拓宽光活性层的光吸收范围是提高钙钛矿太阳能电池光电转换效率的一个有效途径。本文通过在三碘亚铅酸甲脒(HC(NH_2)_2PbI_3简称FAPbI_3)前驱液中混入一定比例的碘化甲铵(CH_3NH_3I简称MAI)并将其退火温度从150℃降低到100℃,不仅能有效改善钙钛矿薄膜的表面形貌和结晶度,还能得到比三碘亚铅酸甲铵(CH_3NH_3PbI_3简称MAPbI_3)更窄带隙的薄膜,由此得到效率达14.8%钙钛矿太阳能电池器件。