【Adv.Mater.】四川大学程沛等|无共轭给体也能做有机光伏电池，突破7.21%效率与400小时热稳定极限！
文章标题： Stable and Low-Cost Organic Photovoltaics Without Conjugated Donors
通讯作者： Jiayu Wang
文章概要
引言
虽然有机太阳能电池的能量转换效率已经突破20%大关，但其迈向工业化生产仍面临着严峻的稳定性瓶颈。传统器件中广泛使用的空穴传输层材料由于具有酸性，极易腐蚀ITO阳极并导致界面分层；同时，常规的共轭聚合物给体材料合成成本高昂，且存在批次差异性大、在运行压力下易引入深能级缺陷等问题，严重阻碍了大面积商业化应用。为了攻克这些难题，研究团队大胆创新，引入了成本极低且极具本征耐用性的无机p型半导体硫氰酸亚铜（CuSCN）作为多功能材料，同时替代传统的空穴传输层和有机共轭给体，为开发高效、长寿命且低成本的下一代有机光伏技术开辟了全新的可行路径。
Chemical structures, device architectures, and performance of the devices. (a) Chemical structures of CuSCN, L8-BO and DIO. (b) Schematic diagram of the fabrication process for PHJ and BHJ devices. (c) The J–V characteristics. (d) PCE reproducibility. (e) EQE spectra of the devices with different active layers.
主要实验及结论
研究团队构建了基于CuSCN与非富勒烯受体L8-BO的平面异质结（PHJ）和体异质结（BHJ）器件。实验显示，PHJ器件受限于较小的给受体接触界面，光电转换效率仅为2.31%；而将两者共混的BHJ器件有效扩大了界面面积，使效率显著提升至5.48%。进一步引入0.30%体积分数的1,8-二碘辛烷（DIO）添加剂后，激子淬灭效率升至54.50%，电荷迁移率大幅提高，同时协同抑制了缺陷辅助和双分子复合。这使得器件最终斩获了7.21%的最高光电转换效率，刷新了无共轭给体有机光伏器件的最高性能纪录。
Photophysical properties of the films. (a,b) Steady-state PL spectra of (a) L8-BO, PHJ, and BHJ films, and (b) L8-BO(DIO) and BHJ(DIO) films excited at 780 nm. (c) Normalized PL decay tracked at the respective PL peak positions of different films. The lifetimes listed in the graphs are calculated from bi-exponential fits to the data (solid lines). (d–h) 2D PL spectra of (d) L8-BO, (e) L8-BO(DIO), (f) PHJ, (g) BHJ and (h) BHJ(DIO) films. (i) PLQE values of the films. All films were excited using a 760 nm laser.
Exciton dissociation, charge transport, charge recombination and charge extraction in devices. (a) _J_ph versus _V_eff characteristics of the devices. (b) Photo-CELIV curves of the devices. (c) _V_OC and (d) _J_SC dependence on light intensity for the devices. (e) TPC curves of the devices. (f) Charge carrier lifetime under different _P_light obtained from TPV experiments of the devices. The normalized FTPS-EQE and EL spectra of (g) PHJ, (h) BHJ, and (i) BHJ(DIO), respectively.
Surface and cross-sectional SEM images of the active layer films. (a) Surface and (d) cross-sectional SEM of PHJ films. (b) Surface and (e) cross-sectional SEM of BHJ films. (c) Surface and (f) cross-sectional SEM of BHJ(DIO) films.
2D GIWAXS patterns and line-cut GIWAXS profiles of the active layer films. (a–c) 2D GIWAXS patterns of (a) PHJ, (b) BHJ and (c) BHJ(DIO) films. (d) Line-cut GIWAXS profiles of different films along the OOP (solid line) and IP (dashed line) directions. (e–g) Deconvolution of the high-q peaks in line-cut GIWAXS profiles. (e) PHJ, (f) BHJ and (g) BHJ(DIO) films.
形貌与结构表征进一步揭示，DIO添加剂能够有效平衡无机给体与有机受体间的结晶动力学，促使活性层形成高度互穿的3D纤维状网络结构，从而优化了电荷分离与传输通道。得益于无机材料优异的本征稳定性，该器件在85°C的高温热老化测试中，经历近400小时后仍能维持80%的初始效率，远超传统全有机器件仅数小时的寿命。更重要的是，在严苛的ISOS-L-3湿热运行协议下，器件连续工作900小时后仍保留了约50%的初始效率，展现出传统全有机体系难以企及的工业化耐用性前景。
AFM height images, phase images and PiFM images of the active layer films. (a, f, k) AFM height images and (b, g, l) corresponding phase images of PHJ, BHJ and BHJ(DIO) films. (c, d, h, i, m, n) PiFM images at 929 cm−1 (CuSCN) and 1530 cm−1 (L8-BO). (e, j, o) Overlay of PiFM signals at 929 and 1530 cm−1.
Thermal stability, degradation of photovoltaic parameters and MPP tracking stability for OPVs devices. (a) The normalized PCE under 85°C conditions. (b) The normalized _J_SC under 85°C conditions. (c) The normalized _V_OC under 85°C conditions. (d) The normalized FF under 85°C conditions. (e) The normalized PCE under ISOS-L-3 protocol (MPP tracking under 100 mW cm−2 illumination at 65°C and 50% RH).
总结及展望
本项研究成功将低成本的无机半导体材料CuSCN引入到有机光伏器件中，兼顾了空穴传输与光电给体的双重功能。这一策略不仅摆脱了传统有机光伏对昂贵聚合物给体材料的依赖，还将器件的高温热稳定性和操作寿命推向了全新的高度，为有机太阳能电池的工业化进程提供了低成本的解决方案。展望未来，进一步攻克大面积薄膜的均匀沉积技术、实现更精准的缺陷控制，并充分发挥CuSCN材料高透光性的先天优势来开发高效率的半透明光伏器件，将是推动该材料体系真正走向实际商业化应用的关键一步。