Bentham Instruments Limited

+44 (0)118 975 1355

Request Information

Spectral Characterisation of Photovoltaic Devices

This guide provides an overview of the spectral characterisation techniques used in the evaluation of their efficacy in the goal of harnessing a maximum of energy from the sun and artificial sources of light.

Measurement Quantities

Along with an I-V measurement, the following quantities provide the most information of material and PV device function.

Spectral Response

The spectral response (A W-1) of a PV device provides information on the physics at play in the global device, taking into account not only the material, but also the reflectance and transmittance of the device.


This measurement is performed by shining a monochromatic probe beam onto the sample and registering the photocurrent generated as a function of wavelength.


Care should be taken to ensure the probe beam is not shaded by electrical connections, or that the shading is taken into account by correcting the resulting response.

The probe is first characterised, using a detector of known responsivity (A.W-1) to determine the power in the beam. Subsequent measurement of the photocurrent generated by the device under test as a function of wavelength allows for the determination of spectral responsivity.


External Quantum Efficiency (IPCE)


The external quantum efficiency (EQE) is defined as the number of electrons provided to the external circuit per photon incident on the device, and is directly obtained from the spectral response measurement by the following argument.

The number, n, of electrons generated by the device, n=(It/e), where I is the generated current, t time and e the charge of the electron. 

The number, m, of photons, incident on the sample, m= Pt/ Ev>, where P is the power in the beam, t time, and Ev the photon energy. The quantum efficiency, η, is defined as,

η = 100.n/m = 100.(It/e)/(Pt/Ev) = 100.(I/P).(Ev/e)

=> η= 100.S.(hc/e).(1/λ)≈1239.84.S/ λ (%)

Where S is the spectral responsivity in A.W-1 and λ the wavelength in nm. EQE can therefore be determined directly from a measurement of the spectral response.

Categories: Solar & Photovoltaics

What’s new

  • download

    Introducing the TLS120Xe high power tuneable light source

    News | 1 May 2018

    Bentham Instruments is pleased to announce the introduction of the TLS120Xe high power tuneable light source. Delivering superlative stability and continuous tuning over 280-1100nm, put the power of monochromatic light at your fingertips.

  • csm

    PVE300 Photovoltaic EQE (IPCE) and IQE solution

    Products | 16 Jan 2018

    The PVE300 system is an essential tool in photovoltaic research and production line quality processes, employed in the accurate determination of solar cell spectral response/ EQE (IPCE) and IQE.

  • 6

    PhotoTest450 Portable In Vivo Monochromator Phototesting

    Products | 16 Jan 2018

    The PhotoTest450 is a trolley-based high irradiance source of UVB-UVA– and visible monochromatic radiation, designed for in vivo application, representing a key tool in phototoxicity testing, photogenotoxicity testing and in the investigation of potential phototoxic risk in trials of topical and systemic drugs.

  • 5

    BPC300 Photochromic Lens Spectrophotometer

    Products | 16 Jan 2018

    The BPC300 spectrophotometer offers accurate characterisation of photochromic (photosensitive) lens transmission in the faded and AM2 conditioned states.

  • 4

    ULS300 Variable, Constant Colour Temperature Luminance Source

    Products | 16 Jan 2018

    The ULS300 is designed for applications requiring a variable, yet Constant Colour Temperature (CCT), luminance source. Comprising a stable 250W quartz tungsten halogen lamp (QTH), light is transported to a 300mm diameter integrating sphere via an eight branch fibre for homogeneous illumination.

Search all our content