A photovoltaic device structure based on internal electron emission
A photovoltaic device structure based on internal electron emission
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DOI：
10.1038/nature01316
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发表时间：
2003-02-06
期刊：
影响因子：
64.8
通讯作者：
Tang, J
中科院分区：
文献类型：
--
作者：
McFarland, EW;Tang, J
自从20世纪50年代开发出第一个太阳能电池以来，人们一直在积极寻找具有成本效益的光伏器件(参考文献1-3)。在传统的固态太阳能电池中，电子-空穴对是通过半导体中的光吸收产生的，电荷分离和收集是在半导体内部电场的影响下完成的。在这里，我们报道了一种多层光伏器件结构，其中光子吸收发生在沉积在超薄金属-半导体结肖特基二极管表面的光接收器上。光激发的电子被转移到金属上，并以弹道方式传输到肖特基势垒和越过肖特基势垒，从而提供光电流输出。低能(类似于1 eV)的电子在贵金属4，5中具有惊人的长弹道路径长度，使得很大一部分电子被收集。与传统电池不同，该器件中的半导体只用于多数电荷的传输和分离。在Au/TiO2TiO2Ti多层膜结构上使用荧光素感光器制作的器件，在100 mW cm(-2)可见光照射下，典型的开路光电压为600-800 mV，短路光电流为10-18 MUA cm(-2)：内部量子效率(每个吸收的光子的电子数)为10%。这种光伏能量转换的替代方法可能为使用各种材料的耐用低成本太阳能电池提供基础。
There has been an active search for cost-effective photovoltaic devices since the development of the first solar cells in the 1950s (refs 1-3). In conventional solid-state solar cells, electron-hole pairs are created by light absorption in a semiconductor, with charge separation and collection accomplished under the influence of electric fields within the semiconductor. Here we report a multilayer photovoltaic device structure in which photon absorption instead occurs in photoreceptors deposited on the surface of an ultrathin metal-semiconductor junction Schottky diode. Photoexcited electrons are transferred to the metal and travel ballistically to-and over-the Schottky barrier, so providing the photocurrent output. Low-energy (similar to1 eV) electrons have surprisingly long ballistic path lengths in noble metals 4,5, allowing a large fraction of the electrons to be collected. Unlike conventional cells, the semiconductor in this device serves only for majority charge transport and separation. Devices fabricated using a fluorescein photoreceptor on an Au/TiO2/Ti multilayer structure had typical open-circuit photovoltages of 600-800 mV and short-circuit photocurrents of 10-18 muA cm(-2) under 100 mW cm(-2) visible band illumination: the internal quantum efficiency (electrons measured per photon absorbed) was 10 per cent. This alternative approach to photovoltaic energy conversion might provide the basis for durable low-cost solar cells using a variety of materials.