Tran Van-Huong, Kim Sung-Kon, Lee Soo-Hyoung
School of Semiconductor and Chemical Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea.
ACS Omega. 2019 Nov 4;4(21):19225-19237. doi: 10.1021/acsomega.9b02551. eCollection 2019 Nov 19.
Tin oxide (SnO) has been widely accepted as an effective electron transport layer (ETL) for optoelectronic devices because of its outstanding electro-optical properties such as its suitable band energy levels, high electron mobility, and high transparency. Here, we report a simple but effective interfacial engineering strategy to achieve highly efficient and stable inverted organic solar cells (iOSCs) via a low-temperature solution process and an SnO ETL modified by zwitterion nondetergent sulfobetaine 3-(4--butyl-1-pyridinio)-1-propanesulfonate (NDSB-256-4T). We found that NDSB-256-4T helps reduce the work function of SnO, resulting in more efficient electron extraction and transport to the cathode of iOSCs. NDSB-256-4T also passivates the defects in SnO, which serves as recombination centers that greatly reduce the device performance of iOSCs. In addition, NDSB-256-4T provides the better interfacial contact between SnO and the active layer. Thus, a higher power conversion efficiency (PCE) and longer device stability of iOSCs are expected for a combination of SnO and NDSB-256-4T than for devices based on SnO only. With these enhanced interfacial properties, P3HT:PCBM-based iOSCs using SnO/NDSB-256-4T (0.2 mg/mL) as an ETL showed both a higher average PCE of 3.72%, which is 33% higher than devices using SnO only (2.79%) and excellent device stability (over 90% of the initial PCE remained after storing 5 weeks in ambient air without encapsulation). In an extended application of the PTB7-Th:PCBM systems, we achieved an impressive average PCE of 8.22% with SnO/NDSB-256-4T (0.2 mg/mL) as the ETL, while devices based on SnO exhibited an average PCE of only 4.45%. Thus, the use of zwitterion to modify SnO ETL is a promising way to obtain both highly efficient and stable iOSCs.
氧化锡（SnO）因其优异的电光性能，如合适的能带能级、高电子迁移率和高透明度，已被广泛用作光电器件的有效电子传输层（ETL）。在此，我们报告一种简单而有效的界面工程策略，通过低温溶液法以及用两性离子型非离子去污剂磺基甜菜碱3-(4-丁基-1-吡啶基)-1-丙烷磺酸盐（NDSB-256-4T）改性的SnO ETL来制备高效且稳定的倒置有机太阳能电池（iOSC）。我们发现NDSB-256-4T有助于降低SnO的功函数，从而实现更高效的电子提取并传输至iOSC的阴极。NDSB-256-4T还钝化了SnO中的缺陷，这些缺陷充当复合中心，会极大降低iOSC的器件性能。此外，NDSB-256-4T在SnO与活性层之间提供了更好的界面接触。因此，相较于仅基于SnO的器件，预计SnO与NDSB-256-4T组合的iOSC具有更高的功率转换效率（PCE）和更长的器件稳定性。凭借这些增强的界面特性，以SnO/NDSB-256-4T（0.2 mg/mL）作为ETL的基于P3HT:PCBM的iOSC表现出更高的平均PCE，为3.72%，比仅使用SnO的器件（2.79%）高出33%，并且具有出色的器件稳定性（在未封装的环境空气中储存5周后，仍保留超过90%的初始PCE）。在PTB7-Th:PCBM体系的扩展应用中，以SnO/NDSB-256-4T（0.2 mg/mL）作为ETL时，我们实现了令人印象深刻的平均PCE为8.22%，而基于SnO的器件平均PCE仅为4.45%。因此，使用两性离子改性SnO ETL是获得高效且稳定的iOSC的一种有前景的方法。
