Organic–inorganic halide perovskites are promising materials for next‐generation photovoltaic device due to their attractive photoelectrical properties such as strong light absorption, high carrier mobility, and tunable bandgap. Generally, perovskite solar cells require carrier transport layers (CTL) to provide a built‐in electric field and reduce the recombination rate. However, the construction of suitable electron‐ and hole‐transport layers is not cost effective, impairing the commercial application of the devices. An n–p perovskite homojunction absorber with a graded bandgap is developed by introducing a three‐step dynamic spin‐coating strategy and variable valence Sn elements. The bandgap of the perovskite absorber is gradually manipulated from 1.53 eV (the bottom) to 1.27 eV (the top). The electronic behavior is also transformed from n‐type (excess PbI₂, the bottom) to p‐type (Sn vacancy, the top) in a very short distance (50 nm). This designed perovskite homojunction electronic structure not only expands the light harvesting range from 800 to 970 nm which provides potential to break the PCE limits, but also promotes oriented carrier transportation and weakens the dependence on CTL. The demonstrated asymmetrical active layer shows a brand‐new approach to simplify the device structure and boost the performance of CTL‐free perovskite solar cells.

中文翻译：

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具有固有n–p同质结的分级带隙钙钛矿，扩大了光子的收集范围，并实现了所有无传输层的钙钛矿太阳能电池

有机-无机卤化物钙钛矿因其吸引人的光电特性（如强光吸收，高载流子迁移率和可调节带隙）而成为下一代光伏器件的有前途的材料。通常，钙钛矿太阳能电池需要载流子传输层（CTL）来提供内置电场并降低复合率。然而，合适的电子和空穴传输层的构造不是成本有效的，这损害了器件的商业应用。通过引入三步动态旋涂策略和可变价Sn元素，开发了具有梯度带隙的np钙钛矿同质结吸收剂。钙钛矿吸收体的带隙逐渐从1.53 eV（底部）调整到1.27 eV（顶部）。₂，底部）到p型（Sn空位，顶部），距离很短（50 nm）。这种设计的钙钛矿同质结电子结构不仅将光收集范围从800 nm扩展到了970 nm，这提供了突破PCE极限的潜力，而且还促进了定向载流子传输并减弱了对CTL的依赖性。演示的非对称有源层展示了一种全新的方法，可简化设备结构并提高不含CTL的钙钛矿太阳能电池的性能。