Abstract：
Although power conversion efficiency (PCE) of solar cells (SCs) continues to improve, they are still far from practical application because of their complex synthesis process, high cost and inferior operational stability. Carbon quantum dots with high material stability and remarkable photoluminescence are successfully used in light-emitting diodes. A good light emitter should also be an efficient SC according to the photon balance in Shockley-Quieisser formulation, in which all excitons are ultimately separated. However, the finite quantum-sized sp2 domain leads to tight exciton bonding, and highly delocalized electron clouds in irregular molecular stacks form disordered charge transfer, resulting in severe energy loss. Herein, an axially growing carbon quantum ribbon (AG-CQR) with a wide optical absorption range of 440-850 nm is reported. Structural and computational studies reveal that AG-CQRs (aspect ratio ≈2:1) with carbonyl groups at both ends regulate energy level and efficiently separate excitons. The stacking-controlled two-dimensional AG-CQR film further directionally transfers electrons and holes, particularly in AB stacking mode. Using this film as active layer alone, the SCs yield a maximum PCE of 1.22%, impressive long-term operational stability of 380 h, and repeatability. This study opens the door for the development of new-generation carbon-nanomaterial-based SCs for practical applications.
摘要：
尽管太阳能电池（SCs）的功率转换效率（PCE）不断提高，由于其复杂的合成过程，它们离实际应用还很远，成本高，运行稳定性差。具有高材料稳定性和显着光致发光的碳量子点已成功用于发光二极管。根据Shockley-Quieisser配方中的光子平衡，良好的光发射器也应该是有效的SC，其中所有激子最终被分离。然而,有限量子大小的sp2域导致紧密的激子键合，不规则分子堆叠中高度离域的电子云形成无序的电荷转移，造成严重的能量损失。在这里，据报道，轴向生长的碳量子带（AG-CQR）具有440-850nm的宽光吸收范围。结构和计算研究表明，两端具有羰基的AG-CQR（纵横比≈2：1）可调节能级并有效分离激子。堆叠控制的二维AG-CQR薄膜进一步定向传输电子和空穴，特别是在AB堆叠模式下。单独使用这种薄膜作为活性层，SCs产生的最大PCE为1.22%，令人印象深刻的380小时的长期运行稳定性，和可重复性。这项研究为开发新一代基于碳纳米材料的SCs的实际应用打开了大门。
