van Gorkom Bas T, Simons Aron, Remmerswaal Willemijn H M, Wienk Martijn M, Janssen René A J
Molecular Materials and Nanosystems & Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, Netherlands.
Dutch Institute for Fundamental Energy Research, De Zaale 20, Eindhoven 5612 AJ, Netherlands.
ACS Appl Energy Mater. 2024 Jul 11;7(14):5869-5878. doi: 10.1021/acsaem.4c01077. eCollection 2024 Jul 22.
In p-i-n perovskite solar cells optical excitation of defect states at the interface between the perovskite and fullerene electron transport layer (ETL) creates a photocurrent responsible for a distinct sub-bandgap external quantum efficiency (EQE). The precise nature of these signals and their impact on cell performance are largely unknown. Here, the effect of n-doping the fullerene on the EQE spectra is studied. The n-doped fullerene is either deposited from solution or by coevaporation. The latter method is used to create undoped-doped fullerene bilayers and investigate the effect of the proximity of the doped region on the EQE spectra. The intensity of the sub-bandgap EQE increases when the ETL is n-doped and also when the device is biased with green light. Using these results, the sub-bandgap EQE signal is attributed to originate from electron trap states in the perovskite with an energy below the conduction band that are filled by excitation with low-energy photons. The trapped electrons give rise to photocurrent when they are collected at a nearby electrode. The enhanced sub-bandgap EQE observed when the ETL is n-doped or bias light is applied, is related to a higher probability to extract trapped electrons under these conditions.
在p-i-n钙钛矿太阳能电池中，钙钛矿与富勒烯电子传输层（ETL）界面处缺陷态的光激发产生了一种光电流，该光电流导致了明显的子带隙外部量子效率（EQE）。这些信号的确切性质及其对电池性能的影响在很大程度上尚不清楚。在此，研究了对富勒烯进行n型掺杂对EQE光谱的影响。n型掺杂的富勒烯可通过溶液沉积或共蒸发来制备。后一种方法用于制备未掺杂-掺杂的富勒烯双层，并研究掺杂区域的接近程度对EQE光谱的影响。当ETL进行n型掺杂时以及器件用绿光偏置时，子带隙EQE的强度都会增加。利用这些结果，子带隙EQE信号被归因于源自钙钛矿中能量低于导带的电子陷阱态，这些陷阱态通过低能光子的激发而被填充。当捕获的电子在附近的电极处被收集时，就会产生光电流。当ETL进行n型掺杂或施加偏置光时观察到的增强的子带隙EQE，与在这些条件下提取捕获电子的更高概率有关。
